Rec.antiques.radio+phono FAQ
Sorry about the somewhat rough character of what follows. It's too
long for me to take it and clean it up, so here it is, just as I saved
it off the net.
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From: vancleef@netcom.com (Hank van Cleef)
Subject: Rec.antiques.radio+phono General Questions(FAQ: 1/9)
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Rec.antiques.radio+phono Frequently Asked Questions (part 1)
Revision Date Notes
1.1 Oct. 20, 94. Second version---major editing. Added two new
sections for sources-of-supply list.
1.2 Dec. 10, 1994. Minor corrections and revisions.
1.3 Jan. 8, 1995. Put in boatanchor mail list info.
1.4 Feb. 26, 1995 Approval to post on news.answers granted
1.4 May 8, 1995 Charter discussion and revised format notice
1.5 Sept. 3, 1995 Add new newsgroup cross references.
2.0 Nov. 20, 1995 Split FAQ from 5 sections to 9 sections
2.1 March 3, 1996 Revise charter disc., boatanchor pointers
Part 1 - Introduction to the FAQ
------------------------------------------------------------------------------
FAQ editor: Hank van Cleef. Email vancleef@netcom
This is a regular posting of frequently-asked questions (FAQ) about
antique radios and phonographs. It is intended to summarize some common
questions on old home entertainment audio equipment and provide answers
to these questions.
Regular FAQ postings can help save network bandwidth and maintain a good
signal-to-noise ratio in the newsgroup. However, they can't do it alone - you,
the reader, have to use them.
* If you are a new user, please print and review the FAQ articles and look at
the instructions in the news.announce.newusers newsgroup before posting any
articles. If you don't find the answer in the FAQ and you have tried
elsewhere, then you have "done your homework" and it is acceptable to ask
the question on the UseNet newsgroups. Along with your question, please
state where else you have looked for the answer so others also know that
you have done your homework.
* If you are an experienced user, please help by refraining from answering
frequently-asked questions on the newsgroup if they are already answered by
the FAQ articles. Instead, send e-mail to the user who asked the question.
(It will be helpful if you include the part of the FAQ that answers their
question, but not the whole thing.)
The FAQ cannot always prevent people from posting repetitive questions. But
even if hundreds of questions get posted, it saves you from having to answer
them hundreds of times. Also, a friendly pointer to the FAQ in your first
answer can help that person refer to the FAQ in the future. That is when we
can begin to get a real savings of network bandwidth.
To reduce the size of articles, the FAQ information is posted in 5 parts:
Part 1 - Introduction to the FAQ and general questions.
(Editor: Hank van Cleef, vancleef@bga.com).
Part 2 - General questions about acoustical phonographs.
(Editor: George Conklin, george@nccu.edu)
Part 3 - Sources of spares and services for acoustic phonos.
Part 4 - General questions about vacuum tube radios and phonos.
Part 5 - Sources of spares and services for old radios.
Part 6 - Cosmetic cleanup and cabinet finish questions
Part 7 - Technical questions about vacuum tube radios and phonos
Part 8 - Tools and test equipment
Part 9 - Miscellaneous and other antique home entertainment devices
Please do not E-mail technical questions, requests to identify various
items, or technical questions to the Faq editors. Post them to the
newsgroup instead. You will get better answers more quickly by
posting.
(March '96) My mailbox is getting far too many questions that I don't
know the answers to, and I am responding with a form message that says
"I don't know, post to the group." So I'll repeat:
PLEASE DON'T MAIL QUESTIONS TO THE FAQ EDITORS. POST YOUR QUESTIONS TO
THE NEWSGROUP. The FAQ editors read the newsgroup regularly, and
generally respond where they have information. We have put a lot of
general information in the FAQ, and a lot of it has come from discussion
on the newsgroup, not from our own knowledge. You'll get more and
better answers from posting to the newsgroup, and if we've got something
to contribute, we'll do it there. Trying to use us as consultants
simply wastes your time and ours.
The charter for the rec.antiques.radios+phonos follows immediately,
after which are some of the top frequently-asked questions.
Newsgroups line:
rec.antiques.radio+phono Audio devices and materials of yesteryear.
CHARTER
Discussion of the use, repair, and collecting of early standard-broadcast
radios, phonographs, and any other similarly-related items designed for home
entertainment sound receiving or sound reproduction.
This group is intended to be a forum for those with an interest
in sound-receiving and sound-reproduction equipment that was generally
manufactured prior to the widespread use of transistors. The group's
discussion, however, will not be strictly limited to vacuum-tube and
mechanical devices, and those with an interest in early transistor radios,
early televisions, and other such items that reflect pioneering audio
technology will be welcomed.
Exclusions:
Amateur radio equipment discussion will be directed to the existing amateur
radio newsgroups and to the boatanchors list. This is only done because
those groups present an established forum for people with an interest in
classic amateur radio equipment. Those classic amateur radio collectors who
also share an interest in early standard-broadcast equipment will fully
appreciate the desire to separate the two interests. Their valuable
expertise will, however, be most welcome in all forums.
Since the summer of 1993, there has been an ongoing discussion among
those interested in antique radios and phonographs (and other related
equipment and materials) about the possibility of forming this
newsgroup. That small core of enthusiasts has rapidly grown in
number, and now includes representatives of museums, technical
specialists, collectors, and novices with an inquisitiveness about
sound reproducing and receiving equipment of the past. With
enthusiasm for the preservation and enjoyment of these superb
expressions of human inventiveness steadily increasing, the time has
come to establish a forum through which knowledge of their history,
restoration, and use can be shared by experts and newcomers alike.
This proposal represents the essence of what an Internet newsgroup can
accomplish--it can produce a collective source of knowledge from which
useful information can be drawn for years into the future.
Bill Robie, August, 1994
In general, this means:
1. This newsgroup has the name "antique" in it, and primarily addresses
home entertainment equipment. It is not a "catch-all" group for
discussing things not covered by other groups.
2. Items of particular interest to readers in this group:
a. Acoustic phonographs of all types.
b. Early electronic phonographs, primarily for playing 78 RPM
disks.
c. Radios of the 1920-50's period. Of particular interest are
Atwater Kent, Philco, and Zenith sets, although all radios by earlier
manufacturers are of interest to the group.
3. While much of the discussion the group is about radios and phonos of
US manufacture, we welcome discussion of non-US radios and phonos from
the same period sold primarily to a domestic market.
4. There are a great many opinions about what is "antique" and what
isn't. The focus of the discussion that led to creation of this
newsgroup was on phonograph and radio technology of the 1890-1950 era.
The group does include some discussion of:
a. Monaural vacuum tube "high fidelity" equipment.
b. Early hybrid and transistor home entertainment designs.
c. Early black and white televisions, and a few color sets.
However, post-1950's technology generally diverges from the focus of
this newsgroup. We generally regard 1960 as a cutoff date for
appropriateness in this group.
d. Instrumentation suitable for use in design, repair, and
calibration of antique home entertainment items. This includes
laboratory-grade equipment as well as service shop equipment.
e. Discussions about technological history, recording and
broadcasting practices, etc., have been interesting areas of discussion
in the group.
5. While not originally sold as "home entertainment" equipment, there
is an interest in jukeboxes, early musical devices such as the Hammond
organ, and movie theater audio, particuarly items manufactured before
WW II.
6. We welcome participation by "hams," and include some discussion of
old tube-type communications receivers, particularly from the '30's and
'40's in this group. Amateur radio issues in general are already covered
by the rec.radio.amateur.* groups.
(March '96). The "boatanchor" mail list, which was previously mentioned
here, is, according to the list administrator, a paid subscription list
as of March 15, 1996.
7. Casual buy, sell, swap, and trade, of old radios and phonos, parts,
are within the charter. Please keep in mind that this is a discussion
group, with many non-collectors who have one or two items that they
enjoy. This is not a place to hawk your wares. If you have an old radio
or phono or two, or want to buy a specific make and model of something,
then post here. Do not post blanket "WTB (wanted to buy) notices for
any and all old radios, old transistor radios, phono records, candlestick
phones, etc. Also, do not post anonymously (AOL, Prodigy, and Compuserve
users take particular note, as these systems do not give posters a clear
identity). Give a geographic location.
Before posting a buy/sell/swap item here, consider posting to one of the
newsgroups set up for that purpose. Rec.antiques.marketplace is the
principal group for antique trading, and is regularly read by readers of
this group who want to buy and sell. Rec.radio.swap is a general group
for electronic items of all types. Rec.audio.marketplace,
sci.electronics.marketplace are also good groups to use, particularly
for post-WW II items. Consider using a regional marketplace or forsale
newsgroup, particularly if you are talking about something you do not
want to ship. Remember that this group is worldwide.
Dealers of parts, supplies, and services for home entertainment items
are listed in sections 3 and 5 of this FAQ.
8. Binary postings. Please do not post binary files (picture files,
uuencoded data, mime attachments, etc.) to this newsgroup. This is a
Usenet convention, not a charter issue. A number of system
administrators run software that detect and cancel binary postings in
non-binary newsgroups. If you want to post a binary file, find a group
with "binaries" in the name, post there, and post a pointer to it here.
Keep in mind that binary groups are not available on many systems,
because of the traffic volume involved, and are poorly propagated.
Some of the things that don't seem to fit well with this group are:
1. Stereo from the 60's and later, particularly things with bookshelf
speakers. The rec.audio.* newsgroups are the place to discuss these.
2. Computers. Usenet has hundreds of newsgroups devoted to computers,
including old ones.
3. Tape recorders other than vacuum tube reel-to-reel units.
4. Video recorders.
5. Guitar amplifiers.
6. Amateur radio equipment except for older general coverage
receivers that sold to non-hams as home entertainment SWL
(shortwave listening) sets.
7. Phonograph records---trading should be done in the
rec.music.collecting newsgroups.
8. Off-charter and commercial buy and sell postings. This includes
"wanted to buy, old radios" postings from individuals, and any
buy/swap/trade postings from anonymous accounts where name or location
are not given. Repetitive postings are also unwelcome to most of the
readers.
The above are general guidelines, not hard-and-fast rules. If you
receive a response posting or E-mail indicating that your post was off
topic, it will generally point to a more appropriate group. This group
has been historically free of flames. There are some very honest
differences of opinion about many topics, and some of the discussions
are lively. The focus of this group is on positive things. Ad hominum
attacks, flame wars, along with attempts to use the group for commercial
purposes, are not welcome here. Your questions, and your experiences
with old radios and phonos are the lifeblood of the group. Work to make
this group a happy and positive place.
A note on safety: Virtually everything we discuss in this newsgroups
can present safety hazards of one sort or another. In particular are
the energy stored in phonograph springs and the voltages and currents in
electronics equipment. In addition, processes such as soldering
components can cause fires and serious burns if improperly done.
While the subject of safety hazards and safe operation, troubleshooting,
and repair practices is a topic of discussion on the newsgroup, such
discussions are generally far from comprehensive. Additionally, many of
the processes discussed presume knowledge of safe practices, and do not
go into detail about possible hazards. Safety is your responsibility.
While we may discuss techniques and practices that work well for us, and
that we can use safely, we are not prepared to give supervised
instruction or to audit people's safety practices. If you are unsure of
your ability to work in a safe manner, seek out local assistance and
supervision.
Q. What other newsgroups cover similar items?
A. There are several newsgroups covering broadcast and amateur radio;
and audio equipment. Acoustic phonographs, player pianos, etc. are less
likely to be covered in other newsgroups.
Notable among other newsgroups with similar interests:
rec.antiques General discussion of antiques.
rec.antiques.marketplace Buy/sell/swap antiques of all types.
rec.audio.tubes Discussion of later vacuum tube audio.
rec.music.collecting.* Phonograph records. This hierarchy has both
discussion and marketplace groups.
rec.radio.swap Buy and sell any electronic equipment, new or old. This
includes test equipment and accessories.
rec.radio.amateur.equipment Specific to ham radio equipment.
rec.radio.shortwave Discusses shortwave programming,
stations, and receivers.
sci.electronics.repair Repair information, primarily for modern
equipment.
rec.audio.* Discussion of audio equipment. This hierarchy
includes several categories, as well as a marketplace newsgroup.
rec.woodworking Discussion of woodworking, finishes, veneering,
etc. If you are working with an old cabinet, read this group.
Q. Where can I get needles for my Victrola.
A. Contact the Antique Phonograph Supply Company, Route 23, Box 123,
Davenport Center, NY 13751. Phone 607-278-6218. Remember to change
your needles after every play. The engineering concept was simple:
the needles are softer than the record, and will wear without
stressing the record. Some records had grit in the mix to
wear the steel needle.
Q. Where can I get replacement vacuum tubes for my radio?
A. There are several suppliers of tubes. Best known is Antique
Electronic Supply, 6221 S. Maple, Tempe, Arizona 85283, telephone
602-820-5411. See the FAQ section for electronic parts and supplies.
Q. I would like to get an old radio or an old phonograph. Where can
I find one?
A. Generally, these items are where you find them. There are dealers
who specialize in old radios and old phonographs, and these may be the
best source if you want something that has been restored to good working
condition as well as cosmetically. Second hand stores and thrift shops,
estate sales, moving sales, garage sales all can produce interesting
items, and it is possible to find some real bargains. Keep in mind that
the source of supply is attics, barns, storerooms, where these were
tucked away, maybe as much as fifty or seventy years ago. They may or
may not have been working when they were stored.
Keep in mind that acoustical phonographs have parts in their reproducers
that deteriorate over time, and that lubricants deteriorate as well.
Electronic equipment also has components that deteriorate over time as
well. What you are looking at may have been stored in working condition
forty or fifty years ago, and look clean as a whistle, but be in need of
major work before you can use it.
Q. I found an EtherSnarf model YU4Q radio at an estate auction and got
it for $125. Did I get rooked? It looks complete, has ten tubes and a
big oak cabinet with spool legs and lots of gewgaws, and has four
shortwave bands. I don't find it listed in any old radio buyers'
guide.
A. First of all, keep in mind that there were literally hundreds of
radio manufacturers in the US in the 1920-1960 era, and there were some
manufactures who built "trade" radios to be sold under a store's brand
name. Part 3 of this FAQ will help you figure out when this radio was
built, even if it isn't listed in any of the buyers' manuals or in any
of the maintenance manuals that were published at the time.
What an old radio is actually worth depends on many things. First of
all, what is it worth to you? While there is supposedly a market out
there, what a specific radio is actually worth is, in reality, what
someone is willing to pay to buy it from you. You want to keep in
mind the following:
a. The radio may need a lot of work before it will
operate as it was designed to operate.
b. Most radios were "lo-fi" in modern terms. Many of us
actually enjoy the sound, and many of the consoles, cathedrals, and
tombstones were tuned very nicely to the programs sources of the day.
c. While the number of tubes may give some indication of the
quality of the radio, and a big console cabinet is more likely to house
a good radio than a plastic table cabinet, keep in mind that "number of
tubes" and "big cabinet" both were selling points in the 1930-50 era
that meant "high retail price." Some mid-priced consoles look as though
they have a lot more radio in them than they do.
Some people swear by the Bunis "Collectors' Guide to Old Radios" series
written by Marty and Sue Bunis. Others do not feel that their prices
are particularly supportable when trying to sell. Most collectors do
not buy for resale, and buy because they want the item.
Q. My neighbor's grandfather left him a Victor spring-powered
phonograph he wants to sell me for $100. Should I buy it?
A. As with old radios, the "worth" of an old phonograph is its "worth
to you." There are "price guides" and general ideas of what things can
be bought and sold for. However, there are substantial variables, such
as geographic location, condition of the unit, etc.
Keep in mind that you are going to need some records to play on
your machine, and that they are also definitely "lo-fi." Edison fought
electrification to the bitter end, so some of the later Edisons, as well
as the Victor Orthophonic of the mid-twenties, did incredibly well.
Q. I got an old Westinghouse cathedral radio from my neighbor when he
cleaned out it his attic. He told me he put it up there when Fred Allen
left radio, but that it was working when he stored it. I plugged it in
and turned it on. All of the tubes glowed, but nothing came out of the
loudspeaker. After a few minutes, one of the tubes got very red inside
and then, suddenly, liquid shot out of one of the aluminum cans, hit the
bright red tube, and it broke. When I turned the set off, it was
smoking, and this liquid got all over everything like tom cat pee. What
do I do now?
A. Never ever plug in an old piece of electronics gear that hasn't been
used for a few years without checking it out first. Part 4 of this FAQ
describes some of the things to check. Fred Allen left radio in 1949,
so that radio has been stored 45 years.
DON'T PLUG IT IN UNTIL YOU HAVE CHECKED IT OUT!
What I am describing here actually happened to me around 1948. The
problem was a shorted wet electrolytic condenser. The plates of the
rectifier tube, an 80, glowed red, and I shut the radio off, but the
electrolytic boiled, squirted the electrolyte (nasty stuff) onto the 80,
which promptly shattered. Cleanup was a soap-and-water job.
Q. Can I get spares for restoring my Edison phonograph---for my Atwater
Kent radio.
A. Parts 2 and 4 of this FAQ list suppliers of spares for phonos and
radios, respectively. In addition to spares support, there are
people who rebuild phonograph transducers and other subassemblies.
Availability of specific spares depends on several things. OEM spares
support for pre-1930's items was discontinued before WW-II, but in many
cases, items of new manufacture are available. In other cases, such as
the 6U5/6G5 tuning eye tube, commonly used from the '30's to the '50's,
your best bet is to substitute (and there is an adaptor for this
available).
Q. I've never worked on vacuum tube equipment before, but I'm a ham and
I have worked on lots of transistor equipment and small computers. Can
I just jump in and fix my old radio?
A. No. There are some serious differences between old tube equipment
and modern solid state electronics. Here are a few things to consider:
a. DANGER! HIGH VOLTAGE! We are not talking about 110 volts AC,
we are talking about 250-500 volts with plenty of "oomph" behind it.
You generally won't find any fuses in old electronic equipment, and no
protective circuits.
b. Vacuum tube circuits have components and circuitry that
isn't used in solid state equipment.
While the basics of physics regarding voltage, current, resistance,
inductance, and capacitance haven't changed, you'll want to study old
texts that explain the theory of operation of the circuits used. While
developing the skills needed to trouble-shoot and repair vacuum tube
circuits is not difficult, it is very different work from working on
solid state equipment. And, as noted, the presence of genuinely high
voltages for someone used to working with 5 and 12 volts means that you
will need to develop new safe working habits.
Q. I'm all thumbs around mechanical and electronics devices. Can I
find people who know how to make these things work?
A. Yes. You may find someone locally who still does work on tube
electronic equipment, and a few telephone calls to service shops will
point you in the right direction if there is someone in your area.
There are a few people who specialize in repairing and restoring old
phonographs and old radios. While none are listed in this revision of
the FAQ, we may include a few if there is a demand for this information.
For a price, you can have almost any antique "high-tech" device restored
to like-new condition, if not better.
Q. What's the difference between this newsgroup and rec.audio.tubes.
A. Rec.antiques.radio+phono was created to move discussion of acoustic
phonos and old radios (primarily 1920-40 era) from rec.antiques. The
rec.audio.tubes newsgroup was created a year later as a place to
discuss use of vacuum tubes in "high fidelity" and guitar amplifiers.
Q. How do I subscribe to the boatanchors mailing list?
A. (March '96). The following instructions are the last information I
have, and have been in this FAQ since this version of the mail list was
set up in the fall of 1994. However, this list is being converted to
"subscription only" as of March 15, 1996. "Subscription only" means
"send money." I do not know how the listowner plans to handle new
subscribers after March 15.
To subscribe to the boatanchors mail list send e-mail to
listproc@theporch.com. Put the following in the body of the mail
message:
subscribe boatanchors
(the following is abstracted from the listproc response from
theporch.com).
Please *do not* submit such administrative messages to the whole
list! Such messages only irritate the readers. If you remember
only one thing from this message, remember that a "Help" message
to the list processor (listproc@theporch.com) will get you
instructions on how to unsubscribe or change your address.
This subscription is available in two formats. The first, also the
default is to have each posting to the list mailed to you seperately. If
you want it like that, you don't have to do anything. The second option
is to receive digests which means the messages are collected and mailed
out to you only if it exceeds a length limit or a time limit (one day).
To change to the digest form, sent email to listproc@theporch.com with
the following:
set boatanchors mail digest
If you want to temporarly suspend receiving the list but don't want to
sign off the list, you can set your mail to postpone by sending email
to listproc@theporch.com with the following in the body of the mail:
set boatanchors mail postpone
This will stay in effect until you change your mail status to one of:
ack noack or digest (ack the default reflects your posting to
the list back to you)
If you want to read the FAQ for the boatanchors mailing list please
send email to listproc@theporch.com with the following content:
get boatanchors FAQ
Problems that cannot be resolved by sending e-mail to the list processor
should be addressed to:
listown@jackatak.theporch.com
Newsgroups: rec.antiques.radio+phono,rec.answers,news.answers
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From: vancleef@netcom.com (Hank van Cleef)
Subject: Rec.antiques.radio+phono Phono Spares and Services(FAQ: 2/9)
Message-ID: <antique-radio+phono-faq-2-845766911@netcom.com>
Followup-To: rec.antiques.radio+phono
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is over 3 months old, please obtain a new one.
Keywords: FAQ OLD-RADIO OLD-PHONO
Sender: vancleef@netcom6.netcom.com
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Organization: Bluebonnet Firebottle Works
References: <antique-radio+phono-faq-1-845766911@netcom.com>
Date: Sat, 19 Oct 1996 23:15:17 GMT
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Archive-name: antiques/radio+phono/faq/part2
Rec.antiques.radio+phono Frequently Asked Questions (part 2)
1.0 Oct. 20, 94 First version. This material was supplied by
George Conklin (george@nccu.edu).
1.1 Dec. 12, 94 Revisions by George Conklin.
2.0 Second Version May 3,1995 This material was supplied by
George Conklin (george@nccu.edu).
3.0 Third Version, March 1996. This material was supplied
by George Conklin (george@nccu.edu).
Part 2 - Sources of supply, services, and literature for acoustic
phonos
------------------------------------------------------------------------------
FAQ editor: Hank van Cleef. Please E-mail comments about comment of
this section to George Conklin (george@nccu.edu)
This is a regular posting of frequently-asked questions (FAQ) about
antique radios and phonographs. It is intended to summarize some common
questions on old home entertainment audio equipment and provide answers
to these questions.
The most frequently asked question so far is "Where can I buy
steel needles for my Victrola?" Answer: Contact the Antique
Phonograph Supply Company, Route 23, Box 123, Davenport
Center, NY 13751. Phone 607-278-6218. Remember to change your
needles after every play. The engineering concept was simple:
the needles are softer than the record, and will wear without
stressing the record. Some records had grit in the mix to
wear the steel needle.
Books about phonographs are written mostly by hobbyists,
not engineers or academics. Below is a listing of common
sources to get you going in the hobby.
1. "The Compleat Talking Machine" by Eric L. Reiss, Vestal Press,
1986, is the most important book for a beginner. It lists not only
many models, but it tells how to oil a machine and how to make
most repairs. Order from: The Antique Phonograph Supply
Company, Route 23, Box 123, Davenport Center, NY 13751-0123.
(607) 278-6218. Order this book first. A second edition is
being advertised as available in the Summer of 1996. It is
supposed to contain new material and added hints.
2. For books about Edison machines, George Frow has written
the "bibles." For cylinder machines, order "Edison Cylincer
Phonograph Companion." It was newly revised in 1994 and
contains about all you can possibly want to know about the
various models. Note: it does not discuss prices. Earlier
editions of this book are found only in rare book rooms of
a few libraries. The only drawback to this book are the
photographs, which are small and dark. The second book
by Frow covers diamond disc phonographs by Edison (the
'thick' records players): "The Edison Disc Phonographs
and the Diamond Discs: A history with Illustrations),
1982. APSCO sells both. You may also contact
George Frow, "Salterns," Seal Hollow Road,
Sevenoaks, Kent TN13 3SH, England.
3. For Victor machines, there is also one book everyone
uses called "Look for the Dog" by Robert Baumbach. A
new paperback edition is out. The illustrations are good,
but the discussion is more limited than what is found in
Frow's books on Edison. APSO sells this book too.
4. The main 'general' book on phonographs
is called "From Tinfoil to Stereo: The Acoustic Years
of the Recording Industry 1877-1929" by Walter L.
Welch and Leah Brodbeck Stenzel Burt. University
of Flordia Press, 1994. Yes, it is somewhat
scholarly and does contain some errors, as do many
of the books about phonographs. Some reviewers
found dozens of errors on dates.
5. Magazines about phonographs are few and far
between. However, I recommend the following for
the beginner in the hobby because they are readily
available, appear regularly and are nicely done:
A. "Victrola and 78 Journal" is a new journal and
a nice mixture of articles on records and how to care
for your elderly phonograph. Contact Tim Gracyk,
1509 River Oak Way, Roseville, CA 95747.
Email: tgracyk@garlic.com (916) 784-1929.
B. "Hillandale News" published by the City of London
Phonograph and Gramophone Society. This is a nicely
produced magazine. Contact Chris Hamilton,
"Ardlarich", 2 Kirlands Park, Cupar, Fife KY 15 4EP England.
C. "In the Groove," a monthly newsletter published by
the Michigan Antique Phonograph Society. Contact
John Whitacre, Editor, MAPS, 2609 Devonshire,
Lansing, MI 48910. 517-482-7996. If you are
looking for parts, this is the place to start.
They publish resource guide and membership
directory which lists about 800 phonograph
collectors and about every known organization
dealing with phonographs and parts in the
world. This is the document to get if
you want to buy parts or look for local
dealers.
6. As for places to get repairs done,
some members of this news group recommend you
contact Dwayne Wyatt of Wyatt's Music
World, PO Box 601, Lakeport, CA 707 263-5013.
The catalog lists all the parts for various Edison
cylider and Amberola phonographs, with a price for
each and every screw, gear and so forth. Columbia
Grafanola, Models AT, AZ, and Q and some Victors and
Brunswicks are also listed. He sells reproduction
Cygnet Horns.
Also, APSO listed above does compete overhauls
of old phonographs and supplies parts.
The above sources are enough to get you started.
They are not a complete listing of very book about
Victors or Thomas Edison. They are, however,
the most important pieces of information and
enough to answer many (if not all) questions.
For the most new information possible, get the
resource guide from MAPS.
---------------------------------------------------------------
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From: vancleef@netcom.com (Hank van Cleef)
Subject: Rec.antiques.radio+phono Phono General Questions(FAQ: 3/9)
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Archive-name: antiques/radio+phono/faq/part3
Rec.antiques.radio+phono Frequently Asked Questions (part 3)
1.0 Oct. 20, 94 First version. This material was supplied by
George Conklin (george@nccu.edu).
1.1 Dec. 12, 94 Revisions by George Conklin.
2.0 Second Version May 3,1995 This material was supplied by
George Conklin (george@nccu.edu).
3.0 March 12, 1996. Third Version. This material was
supplied by George Conklin (george@nccu.edu).
Part 3 - Frequently-asked questions about phonographs
------------------------------------------------------------------------------
FAQ editor: Hank van Cleef. Please E-mail comments about comment of
this section to George Conklin (george@nccu.edu)
This is a regular posting of frequently-asked questions (FAQ) about
antique radios and phonographs. It is intended to summarize some common
questions on old home entertainment audio equipment and provide answers
to these questions.
Part B: Technical Information
Common Questions about Acoustic Phonographs
The most frequently asked question continues
to be from the very first day of the group: "Where can I buy
steel needles for my Victrola?" Answer: Contact the Antique
Phonograph Supply Company, Route 23, Box 123, Davenport
Center, NY 13751. Phone 607-278-6218. Remember to change your
needles after every play. The engineering concept was simple:
the needles are softer than the record, and will wear without
stressing the record. Some records had grit in the mix to
wear the steel needle.
Question: My phonograph does not work. What can I do?
Answer: There is one excellent book which explains how old
phonographs, gramophones and cylinder players work.
"The Compleat Talking Machine" by Eric Reiss. It is
also available from APSCO listed above. It explains how
to work on a phonograph to get it running again. It contains
detailed photographs.
Question: I have just found this wonderful windup phonograph.
How can I tell if it works? I don't have time to read a book.
What can I do?
Answer: Phonographs are found which look new. Others look as if
they have been sitting in a wet basement for 70 years. But there are
a few quick tests:
1. Does the dealer demonstrate the unit? If it plays and sounds
fine, it probably is in good shape. It is relatively hard to hide
problems with spring motors.
2. Is the spring broken? This means that your turn the crank and
nothing happens. Usually the spring is broken near the center, so the
phonograph does not play. New springs can be found for most
phonographs from the Antique Phonograph Supply Company. Cost: about
$50 if you send in the barrel. If a new spring is not
available, you can patch the old one by following instructions in
the Reiss book listed above. But please note that you may not
want to do this without some experience since you can cut your
fingers off.
3. If the turntable rotates (or the cylinder turns), but you hear
a loud bump while the record is playing, then the spring needs grease.
a. This is not an easy task. Purists will say to take the spring out
of the barrel, clean it and the reload the barrel. Warning: if you try
to do this, you can cut your fingers off. The barrel is a cylinder into
which the spring is wound. Some cheaper units simply have an open
spring. Greasing such a spring is much more easy.
b. Shortcut: You can add grease to the spring without first taking
it out of the barrel. Most barrels had an opening called a graphite
hole. Wind up the unit all the way. Take the plug out of the graphite
hole and force in grease. The original Edison formula, which I have
used, contains 10 parts vasoline to 1 part graphite. Put the screw
back in the hole. Let the unit run down, dispersing the grease.
4. Listen to see if the governor is in good shape. When you play the
unit, is there a high speed vibration. If so, you may need work on the
governor. This is difficult.
5. If the turntable works (or the cylinder turns), then play a
record. What does it sound like? If you hear a lot of vibrations,
or if the sound is bad, you probably need to rebuild the reproducer.
a. Rebuilding an Edison reproducer for a cylinder phonograph is
ususally an easy job. Kits cost $6.00. A new sapphire is $30.00
and is likely to outlast you.
b. Rebuilding a Victor #2 (the most common) is not difficult either.
c. Rebuilding a Diamond Disc reproducer is more difficult. The old
diaphragms take effort to remove without damage. It can be done. Kits
are available. New diamond needles: $60.00. But the old diamond may be
in good shape.
d. Rebuilding the Victor Orthophonic is very difficult and few people
will touch this one. Such reproducers (heads) cost about $100 in
auctions. Many were made of pot metal, and they are gradually falling
apart.
e. Rebuilding other heads requires buying generic parts and doing
the best you can.
6. Ok, I don't know much about mechanical things. What can I do?
You can send the entire works off for repair and cleaning. This costs
about $150 for an Edison unit.
7. What about parts? What if something wears out?
If you buy an Edison or a Victor, most motor parts are still
available. As for the other units around, if something other than
the spring is broken, you might want to look for a different unit
unless you are handy around a machine shop, or are willing to pay to
send the entire motor out for repair.
Question: I just found some 'thick' records. How can I play them?
Answer: Many people think that the standard
78 record is 'thick.' However, the really thick records
were made by Thomas Edison and are called Diamond Discs.
They were made from 1912 until Edison closed his phonograph
business in 1929, one day before the stock market crashed.
In their time, these were the premium records. Do NOT
try to play a diamond disc record with a Victrola steel
needle machine. It will ruin the record and it will not
play. The DDs were recorded vertically, using the hill and
dale method. They were played with a special diamond needle.
You can play such records today at 78 rpm on with a stereo
catridge using either the LP needle or a 78 (3 mil) needle.
Or, better yet, such records still work fine with an
Edison machine.
Question: I just found a "Victrola." What is it worth?
Answer: Most people use the word 'Victrola' as a generic
term, like Frigidaire is used to mean all types of ice box.
Most likely such a term means an upright machine made during
the 1920s and housed in a 'brown box.' Since millions were
made, it is impossible to give a specific value. However,
most upright Victors go for about $400 right now.
Question: Where can I read about my Victrola? Answer:
Buy the book "Look for the Dog" by Robert Baumbach. It
lists all Victor models, starting with the open horn machines.
Some were quite rare; most very common. Production
figures are given. Buy the book from Allen Koenigsberg,
502 E. 17th Street, Brooklyn, NY 11226. Phone 718-941-6835.
Question: Where can I find out about record auctions? Parts?
Supplies for old phonographs? Answer: Join MAPS, the Michigan
Antique Phonograph Society, 2609 Devonshire, Lansing, MI
48910. Phone John Whitacre at 517-482-7996. After you join,
purchase the Resource Directory. It lists hundreds of
dealers and places to buy records and get your phonograph
serviced. It also lists other clubs.
Question: I want to buy an Edison Standard. Can you name
some dealers in my area?
Generally the answer to this question is unfortunately 'no.'
The market for used phonographs remains fragmented. In certain
areas there are well-known dealers. But you are not going to
find one listed in every city. Antique malls often sell machines
that are offered to them. Prices can be high.
Question: I just found a phonograph. I can't remember the name.
Who made old phonographs anyway? Answer: The phonograph was
invented by Thomas Edison. He let it sit on the shelf for 10
years. His patents covered cylinder records, the original format.
Later Berliner obtained a patent for what we call today the 78.
Its virtue was that the 78 could be mass produced easily.
Victor took up the Berliner patent. Edison stayed with
cylinder records. By 1920 it seems as if every furniture
store would put together a case and generic works and a new
brand was born. Sometimes Edison would sell spare cases so
conversion companies would put together parts from different
sources even in well-known cases. Some common brands:
Edison, Victor, Sonora, Brunswick, Silvertone, Zonophone,
Aeolian, Pathe, Granby, Columbia, Vocalian, Harmonola,
Heinman and others.
Question: Where can I learn about the history of the
phonograph? Answer: write to Allen Koenigsberg, 502 E. 17th
Street, Brooklyn, NY 11226. Request a collectors check list.
Most important books can be purchased through him. The
most scholarly is "From Tinfoil to Stereo, 1877-1929" by
Welch and Burt. Unfortunately, the authors concentrate on
the legal fights faced by early phonograph producers, and not
the technological problems the had to overcome to bring talking
machines to market successfully.
Koenigsberg also publishes the "Antique
Phonograph Monthly." It contains interesting articles about
phonographs. Be warned: it comes out every year or so, not
monthly. Since the history of phonographs is a hobby not
a scholarly undertaking, people do this sort of thing in
their spare time. Note: the Monthly has not come out for two
years now, so it may be finished. Check with Allen.
Question: What is a gramophone? Answer: The British refer
to a phonograph which plays flat records as a gramophone. In
British usage, a phonograph plays cylinders only.
Question: I just found an Edison cylinder player.
Where can I find out about how it works? Answer:
There is one authority on Edison players, both cylinder
and the Diamond Disc (DD) type. His name is George
Frow. He wrote two books which define the field.
The book on cylinder phonographs is just about to be
republished in a new edition called "Edison Cylinder
Phonograph Companion, 1877-1929." Available from
several sources, but I have a listing from Koenigsberg
listed above. The book is very complete, but its pictures
are very dark and detract from the excellent material.
The second book covers Edison Diamond Disc machines.
"Edison Diamond Disc Phonographs, 1912-1929." Frow
covers all models, including some which may have never
been made! His research comes from the Edison historical
site in Orange, NJ. Source: write Frow himself at
George Frow, "Salterns" Seal Hollow Road, Sevenoaks, Kent,
TN13 3SH England. He airmails the book, with no delay.
Check for current price. He took my personal check.
Also available from Koenigsberg listed above.
Question: Where can I find a list of cylinders which were
made? Answer: Wax cylinders made up until by Edison 1912 are covered
in a book written by Alan Koenigsberg, 502 E.
17th Street, Brooklyn, NY 11226. Celluloid cylinders
made by Edison are listed in a publication sold by
The City of London Phonograph and Gramophone Society (CLPGS),
Mr. Chris Hamilton, "Ardlarich," 2 Kirklands Park, Cupar,
Fife KY15 4EP, Scotland. Phone: 44 334 543 90.
Question: Are there any magazines which discuss old
phonographs? Yes: Personally, the most interesting
is Hillandale News published by CLPGS listed above.
It is a glossy magazine well produced. It contains
about 40 pages per issue. Also, the Michigan Antique
Phonograph Society has a monthy newsletter which answers
questions from readers.
Question: What are the most common old phonographs?
Answer: The phonographs which have survived today
are Edison, Victor and Columbia. Of the three, Edison
was the most sturdy, although Victor was often well made
also. The Columbia units used more pot metal, which
decays with age.
Question: Are all phonograph cyliders the same? Answer: Not all
phonograph cylinders are the same. The cylinder was the
original format for recording. The most commonly found
ones today are Edison's black wax (Gold Moulded) cylinders.
These play for 2 minutes. Columbia made 2-minute cylinders
wax cylinders until 1902, then switched to making their
cylinders out of celluloid. The celluloid cylinders are often
found today in excellent condition compared to their wax
counterparts.
Later everyone switched to 4-minute cylinders. Edison
always offered kits to upgrade his players. The
4-minute cylinders turned at 160RPM (as did most 2-minute
cylinders) and had 200 grooves per inch.
Edison produced 4-minute wax cylinders and later 4-minute
blue celluloid cylinders. The blue cylinders (called Blue
Amberols) were launched in 1912 and were made until 1929,
long after everyone else quit making them.
I have just found a phonograph in a brown case. When
as it made?
If the phonograph has a large external horn, it was made
before about 1912. After that, the ladies wanted horns inside
a case, hidden from view. If the unit you are looking at has
an enclosed soundbox in a pice of furniture, it was made
from 1910 or so up until the end of the wind up era about
1930. Not many phonographs were made from 1929-1945. The
depression caused a collapse of sales, with one authority
claiming that record sales declined by 90% during the 1930s.
Question: What is the difference between Victor and
Victrola? Answer: The Victor Talking Mahince Company
made external horn phonographs. When they switched to
horns inside of the case, the name -ola was added. Victrola
technically means an internal horn machine. Edison did the
same thing. He called his internal horn cylinder machines
Amberolas.
Question: I have some 78s I got from my family. I am afraid of
hurting them with a diamond needle. How can I play such records?
You can play 78s with a modern phonograph using a diamond needle.
If you have only a stereo stylus, you can still use it to play your
78s without hurting them. Of course, it is best to use about a 3 mil
needle made for the purpose. Modern equipment, tracking at 2 grams, is
quite gentle on records compared to the old Victors, tracking at
several ounces.
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From: vancleef@netcom.com (Hank van Cleef)
Subject: Rec.antiques.radio+phono Radio General Questions(FAQ: 4/9)
Message-ID: <antique-radio+phono-faq-4-845766911@netcom.com>
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Archive-name: antiques/radio+phono/faq/part4
Rec.antiques.radio+phono Frequently Asked Questions (Part 4)
Revision Date Notes
1.1 Oct 24, 94 Was part 2, now part 3. New material and
revisions.
1.2 Dec. 5, 94 Added references to RCA Receiving Tube Manual,
corrections and new material.
2.0 Nov. 19, 95 Move from part 3 to part 4
Part 4 - General questions about vacuum tube radios and phonos.
------------------------------------------------------------------------------
FAQ editor: Hank van Cleef. Email vancleef@netcom.com
This is a regular posting of frequently-asked questions (FAQ) about
antique radios and electronic phonographs. It is intended to summarize
some common questions on old home entertainment audio equipment and
provide answers to these questions.
Q. I've got a <name of radio>. What's it worth?
A. This is the most frequently-asked question in this newsgroup. It is
also the most unanswerable question. You can count on a small home
entertainment set's being worth $5 or $10 if it is complete but not
working, and maybe twice that if it is in good condition and working. Some
consoles may be worth $40 or $50, and some high-end "boatanchor"
communications receivers may be worth $100 or more if they are
restorable. There are a few radios that are reputed to be worth
considerably more, but one very significant variable is geographic
location (in the US), another is whether the radio is shippable out of
an area with a weak market. You can get all sorts of opinions, but in
actuality, the only real way to determine a radio's value is to try to
sell it and see what you are offered. There are simply too many
variables to be able to place any reliable monetary value on antique
electronic equipment of any sort. You will soon discover that what is
being advertised over here for $500 is available over there for more
like $5.00. Good clean electronic equipment restored to good working
condition is worth more money, but generally much less than the costs of
restoration, if one includes any value for skilled labor in doing the
restoration.
Q. What is published to tell me what an old radio is worth?
A. There are some guides that list prices. The most commonly mentioned
is Bunis, Marty and Sue, "The Collector's Guide to Antique Radios." It
is available from Antique Electronic Supply. There are several other
books available from them for identifying old radios, some with price
information. What a specific radio actually is worth may be quite
different than what these guides list. In addition, the condition of
the radio (both cosmetics and electronics) has to be considered. "Antique
Radio Classified" is a buy-and-sell sheet, probably the most accessible
true market information available for inspection.
Q. I just got an old radio at a yard sale for $5. It is a Radio Wire
Television Model J5. When was this radio built? Can I get it to work?
Is this radio worth restoring? Can I get a schematic somewhere.
A. Requests like this send everyone scrambling for their references,
schematics manuals, etc. etc., and sometimes nobody responds. There is
some very basic information that you could, and should, include, that
would get you an answer instantly. If you included "this radio uses
five tubes. They are 12SA7, 12SK7, 12SQ7, 50L6, and 35Z5." See below
on "how to date radios by design features." Listing the tubes often
says everything.
The example used here is one of an endless long list of AC-DC table
radios built after 1940 using this tube complement. This type of set
is known as an "All-American Five." Most people who repaired radios
in the forties and fifties could draw the schematic for any of these
radios from memory----it's a case of "seen one, seen 'em all." This
particular radio has a grand total of 9 resistors (including volume
control), a whopping 14 condensers (including the tuning condenser as
one), three transformers, one oscillator coil, a loop antenna, a
loudspeaker, and a panel lamp. Add the five tubes, and that amounts to
the whopping sum total of 35 electrical components, and if you want to
insist on including the chassis, five tube sockets, cabinet, panel lamp
socket, and cabinet, we are still talking about 50 parts. No wonder
they sold for $4.98 in 1940. If it has value, it is for its case and
mechanical configuration. As a project radio to learn radio repair
and restoration, an AC-DC 5 or 6 tube table set is probably ideal. Most
of these sets need one tube (burned-out heater), new electrolytics and
paper capacitors to get it "working like new."
Typical schematics for All-American Five radios are given in the RCA RC
series and GE Receiving Tube manuals available in reprint from Antique
Electronic Supply. Actual production radios of this design had a
variety of subtle variations, but the typical circuits in the tube
manuals should help you find your way around one of these sets.
Q. I just looked at a Radio Wire Television model B45. It has 13 tubes
and two loudspeakers. I couldn't see all the tubes but I saw a 6H6, two
6L6's, two 5Y3's, and a bunch of metal tubes with top caps. It
has three bands, two shortwave, and a phono, and is in a custom-built
plywood cabinet. What can anyone tell me about this set. The radio
works, but not well. The owner wants $100 for it. Is it worth it?
A. This is the type of radio you should be asking questions about. The
radio itself is a "class act"---high fidelity, 1938 style. It's the
same manufacturer listed in the question above, and shows that
"brands" could range from absurdly cheap to top quality. It also is
typical of the radios that justified service shops paying good money for
Rider's manuals over the years.
As a "collector" radio, it's a difficult one to put dollar value on.
But as a museum piece, an example of what a high-end thirties radio was,
it is a class act. For those who have Rider XVIII, look at Radio Wire
page 18-8, and notice that only the schematic and a few notes are
published, some ten years after the radio was made. (confession: I owned
one of these from about 1948 until sometime in the sixties, and it was
my first really hard-core restoration project. It also was my "hi-fi
amplifier" for many years). If you want an example of high tech
history, it's well worth the $100, and if you restore it, you'll find
that quality is a lasting thing. But restoring a set like this can be a
major project and take a good deal of skill.
Other "high tech" radios that are more readily identifiable by brand
name are the Farnsworth Capehart sets and the 2-chassis Magnavoxes.
McMurdo Silver, E.H. Scott (Scott Radio Laboratories in Chicago) and
Radio Craftsmen are fairly well know high-end receivers. Many of these
last were sold as chassis only for custom installation.
Q. I saw a little table radio with a very pretty plastic case, but the
owner want hundreds of dollars for it. The case looks like marble, but
the radio inside is just another of those 35Z5 and 50L6 five tube jobs.
Why does the owner think its worth almost a thousand bucks?
A. Well, you've stumbled on the collectors' hot item of the nineties,
the "Catalin" case. The reason the owner thinks it is worth this much
is that the collectors' market seems to be willing to pay these prices
for a catalin case. Whether it will continue to do so is open to
question. It is difficult, in a FAQ item, to explain the whimsies of
the "collector" market, because these tend to change.
Q. Well, if a low-tech radio is worth hundreds of dollars because of
its case, and a high-end console with tremendous sensitivity and a
powerful amplifier with good fidelity is worth a lot less, what's the
correlation between price and value?
A. There isn't any. Some radios, such as the Atwater Kent TRF sets and
the RCA catacombs superhets are valuable because they are relatively
rare today, and represent technological history. An old communications
receiver, such as the Hallicrafters SX42, which was also sold as a home
entertainment radio, has much more value to a ham than an old Magnavox
radio-phono, so has value because of its technology. Novelty items,
particularly if they are rare, seem to be high-ticket "collectibles" in
any area. So you see dollar values attached to radios with reading
lights built in, radios with cameras in them, catalin cases, the Sparton
blue mirror sets, incredibly small portables, etc.
Q. I keep hearing about "Neutrodyne," "Regenerative," "TRF," and
"Superheterodyne." What do these terms mean?
A. The first home entertainment radios were crystal sets which used a
single tuned antenna circuit and a crystal detector. When tubes were
added for amplification, these were set up with tuned circuits that had
to be individually tuned to the station being received. These are "TRF"
sets, for "tuned radio frequency." Later on, manufacturers learned how
to build TRF stages using either mechanical coupling between the tuning
condensors or a single ganged condenser, and to provide adjustments to
get them to track (i.e., all tune to the same frequency across the range
of broadcast frequencies), so later TRF sets have one-knob tuning.
The Neutrodyne refers to a method of "neutralizing," or compensating
for, detuning effect of grid-plate capacitances by feeding back an
opposing signal. These sets are TRF sets with neutralizing circuits in
them---generally, another coil in the tuned circuit used to generate the
neutralizing signal.
The superheterodyne uses the physical principle that two oscillators
running at different frequencies will produce "beat" frequencies equal
to both the sum of and difference between the two frequencies. This can
be heard when tuning musical instruments; the principle is the same for
radio frequencies. The incoming RF signal is "mixed" with a local
oscillator signal and fed to a fixed tuned stage that is sensitive to
the difference frequency between the two signals. Use of one or more
fixed-frequency tuned stages gives the set relatively constant
sensitivity and selectivity, both of which are difficult to get in
variable tuned stages. To illustrate what these words mean, take a
common five-tube US table radio and a station at 1000 Khz ( 1
megacycle). An antenna coil and one section of the tuning condenser
(capacitor) are tuned to resonate at 1000 Khz, "selecting" that
frequency. A local oscillator is tuned by the other section of the
tuning condenser to 1455 Khz. In a set with a 12SA7 tube, the
12SA7 is wired as an oscillator, with the oscillator signal appearing on
the first grid (g1). The tuned RF signal is fed to the third grid (G3).
The plate circuit is connected to a transformer tuned to 455 Khz, to
respond to the difference between the frequencies being injected on G1
and G3. Signals at 455, 1000, 1455, and 1455 Khz all appear on the
12SA7 plate (the two fundamentals and the sum and difference), but the
tuned "intermediate frequency" (IF) transformer selects only the 455 khz
signal. This intermediate frequency is generally amplified by one or
more tuned (455 khz) stages---in our example, a 12SK7 with double-tuned
input and output IF transformers (i.e., both the plate and grid circuits
are tuned to resonate at 455 Khz) is used, and the output of that stage
is fed to the a diode detector.
This may sound a bit complicated, and I've left out all the fine points
of the design to focus on "what's supposed to happen."---a good
engineering text discusses design details beyond this description. One
point of terminology----the mixer stage (12SA7) was often called a
"first detector" in early designs; thus, the 12SQ7 diode detector in our
example is called the "second detector," a term that has persisted
through the decades.
One other common early design was the "regenerative" set. In these
sets, an RF amplifier was designed as an oscillator, but provided with a
control that could be adjusted so that the stage wouldn't go into
oscillation. The positive feedback in the stage provided substantially
more gain than a simple tuned circuit would provide. Misadjustment of
the feedback control would make the stage oscillate, producing squeals
in the output, and quite powerful RFI (radio frequency interference) as
well. The "superregenerative" circuit is a refinement that prevents
sustained oscillation, but was generally not used in home entertainment
sets.
(1/95) Roy Morgan forwarded me a description of the super-regen by Dan
Knierim for inclusion---here it is.
>P.S. What's the diff between a super-regen and a regen detector?
>I basically understand the regen circuit (gain stage near oscillation
>behaving as high Q filter) but I don't recall what the principle of
>the super-regen circuit is. And I'm definitely not an RF kinda
>guy these days.
A super-regenerative detector is a gain stage with positive feedback greater
than unity (so that it will oscillate), but with an RC circuit in the plate
or grid supply, so that the increased current during oscillation will lower
the gain over a period of time proportional to the RC time constant, and
finally kill the oscillation. Of course, once the oscillation quits, the
current draw goes down, the RC circuit recharges, the gain goes back up, and
the oscillation starts again. The frequency of this blocking oscillation is
set (by picking the RC time constant) to be well above audible frequencies,
but far below the RF oscillation frequency.
So how does it detect? Any RF input signal at the frequency of the main
oscillation (not the blocking oscillation) will help the main oscillation
restart when the stage is coming out of the blocking mode. If the RF input
increases, the main oscillation will restart faster, the stage will
spend a higher percentage of its time in the oscillating mode, and the
average plate current will be higher (where the average is taken over several
cycles of the blocking oscillation). Thus the detected audio output is just
the plate current run through a low-pass-filter.
The average plate current as a function of RF input amplitude is not very
linear; in fact it has a 1 / natural logarithm nature to it due to the
exponentially rising nature of an oscillator starting up. This makes the
audio quality from a super-regenerative detector low, but also acts somewhat
like AVC. The pk-pk audio output amplitude is more proportional to the
pk-pk RF input amplitude *ratio*. The steep slope of a logarithm near
zero also implies a high sensitivity with very small input signals, which
is one of the super-regens claims to fame.
Some of its many drawbacks are: it makes a racket when not tuned to an
input signal (in other words, it also has a high sensitivity to very small
amounts of noise, in the absence of an input signal above the noise floor);
it is tricky to keep running right; and it radiates like crazy if not
preceded with a separate RF input stage.
By the way, don't sneeze at regen sets just because they don't have a
lot of tubes. I recently read a posting in another group that talked
about a 1920's one-tube setup that blew smoke around some fancy radios.
Edwin Armstrong, who contributed the straight regen, the super-regen,
and FM, was a real genius.
Q. I have an old radio-phono. The radio works fine, but the phono
doesn't make any sound in the loudspeaker at all. What's the deal?
A. Your phono pickup probably uses a Rochelle salt crystal cartridge,
and the salt crystal has failed. You will need a new cartridge. (faq
editor note---I'm including this, and have a radio-phono with a dead
cartridge. What's available?).
Q. I just got an old radio that I think was made in 1939. But it has a
jack on the back labelled "television." It only has a volume
control/on-off switch and tuning control on the front. What's the deal
with the jack? How can a radio receive television, and why is a 1939
radio labelled like this when TV broadcasting didn't really begin until
after the war.
A. You are looking at a marketing ploy. The jack on the back is an
audio input jack, and if there is no switch for it, it is wired
permanently to the top of the volume control (detector output), so has
whatever signal the radio is receiving on it as well. Television was
"just around the corner" in the 1937-39 period and there were some
experimental stations broadcasting what is essentially NTSC video on
Channel 1 (48-54 Mhz) after 1936. Putting these jacks on the radios was
to convince the buying public that their new radio wouldn't be made
obsolete by television "next year." Commercial television actually
began in 1939, but WW II intervened, and the mass-marketing push for TV
did not begin until 1946-7.
Q. I have a console with 6L6's and a twelve-inch loudspeaker. Is this
"high fidelity?" Just what can I expect to hear from my old radio for
audio quality?
A. (9-95) A few readers have exercised your FAQ editor on the topic of
"high fidelity" in the AM band, generally citing the fact that
broadcast transmitters built after 1930 were capable of modulating at
frequencies above 10Khz. The evidence is clear that notwithstanding
transmitter capabilities, there were very few program sources available
to broadcasters that were capable of getting modulation above 5Khz to a
transmitter. Telephone lines used to transmit network programs had
this bandpass limit, as did standard home entertainment and jukebox
phonograph records. Transcription recordings were made at 33-1/3 rpm,
but were not the "microgroove" technology introduced in 1948.
The existence of "high fidelity" receivers in the thirties (either TRF
or using wide IF) is well-documented, but all evidence is that these
were sold for use with the experimental wide bandwidth stations,
particularly in the Northeast US. The vast majority of programming
matched the limited frequency response of most receivers.
The exception to this would be live music, played either in a studio or
in a local concert hall where a telephone link was not required, until
the advent of Armstrong's FM links between New York and New England in
1939.
Microgroove phonograph records with wide bandpass capability, and
magnetic recording, capable of operating beyond 20Khz, were introduced
in the late 1940's, allowing stations to use prepared program sources
that had a wider bandpass capability.
Q. When was magnetic recording introduced? I keep hearing about
"tapes" that were made in the 1930's.
A. You can rest assured that anything involved with home entertainment
was not recorded on magnetic media until the 1947-8 period, and not
regularly used for broadcast purposes until around 1952. While
magnetic recording, using a magnetic wire, was invented by a Dane,
Poulsen, in 1898, the need for a bias to overcome hysteresis distortion
was not recognized until the 1930's. Magnetic recording was used for
military purposes during WWII, which the Germans being the leaders
through much of the period. Wire technology became commercially
available in 1946, using a magnetic steel alloy (fortunately, corrosion
resistant) wire. Formulations for placing magnetic materials on tape
reliably were not available until around 1948, and reel-to-reel tape
only became common around 1951, replacing wire.
The method for getting response above 10Khz. in early magnetic
recorders was simple: move the medium quickly. Webster-Chicago wire
recorders move the wire at about 25 inches per second. Early tape
units operated at 15 IPS.
Worth noting that magnetic recording is not discussed at all in the
Radiotron Designer's Handbook, 4th edition (1952).
Q. I have a nice old Philco cathedral radio that I have listened to for
years. It only gets local stations, and even at maximum volume, is not
particularly loud. Can I get it to work better than it does now?
A. Probably. You have a sixty-year-old piece of electronic equipment
that has probably had two or three tubes replaced, and maybe one bad
capacitor, in those sixty years. In short, it's a candidate for an
electronic overhaul. Some things that may have degraded over the years:
a. Capacitors. Electrolytic capacitor problems generally make
themselves known quite quickly. However, those little wax-impregnated
"paper condensors" may all be leaking current and delivering less
capacitance than needed for good performance.
b. Resistors. These may have "drifted" to a much higher
resistance gradually.
c. Misalignment of tuned circuits. The "tweaks" on the tuning
condenser and the IF transformers generally don't drift very far unless
the coils have absorbed moisture. Altogether too often, the amateur
restorer will tweak the set out of alignment by fiddling with these.
Don't touch them unless you know exactly what you are doing and have the
equipment needed to align the radio.
d. Tired tubes. I put this last, although a lot of people look
here first, and assume that a tube tester's readings will correlate with
set performance. The best test for tube condition is to substitute a
known good tube in each position and seeing if it changes anything. A
sick pentagrid converter tube (6A7, 6A8, 6K8, 6SA7, etc.) may very well
test normally under DC conditions in a tube tester yet fail to oscillate
reliably in the set, particularly on shortwave.
Q. You say "electronic overhaul." Will that restore my set to like-new
performance?
A. Generally, yes---actually, better than new. Modern resistors and
capacitors are better circuit components than were available in the
thirties and forties. Capacitors in particular are much smaller, and
larger values can be used to advantage in some places, particularly in
the filtering circuits.
Q. Modern components? But if I put modern components like mylar
capacitors in the set, it won't be "original" any more.
A. There is a wide range of opinion about use of modern resistors,
capacitors, and wire in an old radio. Some feel that disguising modern
components in the shells of old wax paper capacitors is important. There
are (at least so far as your FAQ editor knows) no clear-cut guidelines
on the "looks" of components installed under a radio chassis. Consensus
seems to agree that all items that are visible when the chassis is
bolted in place should "look like the original radio did."
Q. I have a Philco battery-powered radio. It has a four-prong plug for
the battery. Can I get a converter at Radio Shack and use it to make my
radio work?
A. No. The battery radios required 1.5 volts for the tube filaments and
67-1/2 or 90 volts for "B" (plate) voltage. The 3-way portables
(AC-DC-battery) had built-in battery eliminators, and the tube filaments
were generally wired in series, requiring a 6 or 9 volt "A" battery.
You'll need to make a supply that can deliver 1.5 volts at about 400 ma.
and 90 volts at about 50 ma. for your four-prong Philco. Both have to
be good clean filtered DC. The power-pak-in-the-plug type power units
sold by Radio Shack and others are made to deliver 6-9 volts at
100-200 ma. unfiltered DC.
DATING OLD RADIOS BY THEIR TUBE COMPLEMENT
The development of vacuum tubes, both electrically and mechanically,
advanced at a rapid pace between about 1925 and 1950. The vast majority
of radios sold for home entertainment between 1920 and the late 1950's
were built to various standard circuits. In most cases, checking out
what tubes are used in the radio will place it's date of manufacture
within a few years, identify which of the standard circuits it used, and
give a some indication of the quality of the set. Most radio repair
technicians in the 1930-60 era did not need to look at schematics most
of the time, even when the problem was not a burned-out vacuum tube
heater or filament.
The tube complement is not always an accurate guide, except insofar as
the presence of a given tube indicates that the set was built after that
tube was placed in production. You won't find any 1932 radios using
tubes with octal bases or 6.3 volt filament heaters, and you won't find
any prewar radios with 7-pin miniature tubes. But you may find a 1946
table radio built to a 1935 design. There are also a few other design
features that are very obvious on casual inspection; I'll mention some
of them as we go along.
(New 12-94) In the following discussion, there are references to the
example circuits shown in the RCA Receiving Tube Manual RC-19, dated
1959. This manual is available in reprint from Antique Electronic
Supply. Examples 19-1 through 19-4 in particular show examples of four
standard circuits that were used, either identically or with minor
modifications, in the majority of the smaller "collectible" radios built
from the mid-1930's on.
1. The five or six-tube AC-DC radio with 150 ma. tube heaters wired in
series. Example circuit 19-4 shows one of these radios, using 7-pin
miniature tubes. This design is colloquially called the "All-American
Five" by some of us. The design was first built in 1939, using octal
tubes (i.e., 35Z5 and 50L6 in place of 35W4 and 50C5), so it is also
called by some a "35Z5 radio" or a "50L6 radio." I list this design
first, not only because it dominated home entertainment radio production
for over 20 years, but because it is a very simple superheterodyne
circuit. If you study this circuit and know what every component's
function is, and study an example radio of this design, you'll be
prepared to trouble-shoot and repair most post-1935 radios.
These sets do not have a power transformer, and could operate
in places like mid-Manhattan, which had 110 volts DC as its primary
electrical service. Most of these were built as table radios, although
some were installed in small consoles and radio-phonograph combinations.
Virtually all clock radios use this circuit. These are generally
AM-broadcast-only. The tube set shown in the example is one of three
common sets, having either octal, loctal, or 7-pin mechanical design,
but electrically equivalent. Some sets, particularly in the early
postwar period, were built with mixtures of tube mechanical types,
because of tube shortages and availability, and some sets used more than
one configuration during their production runs.
The six-tube version had an RF preamplifier, and was more sensitive than
the five-tube. Example circuit 19-3 shows the same
basic design with an RF preamplifier stage, with tuned output
(three-section tuning capacitor). Many of the six-tube versions used
resistance coupling between the RF preamplifier and the converter stage
(see Diagram no. 3, p. 339, in RC-19, for a resistance-coupled pentode
circuit). The six-tube version was often called a "35L6 radio" because
a 35L6, 35A5, or 35C5 was used, allowing connection of one more 12-volt
heater in the series heater string. In the fifties, some of these radios
were built with a selenium rectifier, omitting the rectifier tube.
Also, a few manufacturers built a four-tube version that omitted any IF
amplification.
Several low-end "boatanchor" communications sets used this circuit,
adding multiple tuning coils and provisions for a beat-frequency
oscillator. Notable examples are the Hallicrafters S-38, S-41, S-119,
S-120, and Ecophone EC-1 series; and the National NC-46 and SW-54.
The tube complements are:
a. First version, built primarily 1938-40.
(note: this design is similar to the 19-4 example, but is its immediate
prececessor, so has a few substantial differences, noted below).
12A8 RF-converter, 12K7 IF amplifier, 12Q7 detector-audio, 35L6 power
output, and 35Z5 rectifier. The first three tubes had small top caps
for the signal grid connections, with either metal or glass envelopes.
The original glass tubes had a "G" suffix, indicating use of an ST-12
stepped bulb envelope. The major difference between this design and
that shown in example 19-4 is the use of a 12A8, which uses a slightly
different oscillator circuit than the 12SA7, 14Q7, or 12BE6. The other
top-cap tubes are very similar to the single-ended octal tubes which
followed, varying primarily in mechanical construction. 12J8 and 12K8
were sometimes used as converters as well. RC-19 unfortunately omits
any circuits for these converter tubes. This version uses a series
resistor in the heater circuit because the heater voltages do not add up
to "near 120"). The proper place for this resistor, electrically,
is between the rectifier heater and the power amplifier heater.
b. Second version, built 1939-ca. 1960
12SA7 RF-converter, 12SK7 IF amplifier, 12SQ7 detector-audio, 50L6 power
output, 35Z5 rectifier. This is almost the same radio, but using
single-ended tubes in the first three stages and a power output tube
with a 50-volt heater. The major difference is in use of a 12SA7 in
place of the 12A8---these tubes are different internally. Note that the
sum of the nominal heater voltages adds up to 122.8 volts, allowing
operation without need for any series resistor in the heater circuit.
c. Postwar version, 1945-mid '60's
12BE6 RF-converter, 12BA6 IF amplifier, 12AT6 detector-audio, 50B5 power
output, 35W4 rectifier. The only difference from b., above,is the use of
seven-pin miniature tubes. All are electrically identical to the octal
versions above. Some sets were built using a mix of seven-pin miniature
and octal tubes, however, the presence of seven-pin miniature tubes
indicates that the set is postwar production.
d. Loctal tube version, 1940-ca. 1960
14Q7 RF-converter, 14A7 IF, 14X7 detector-audio, 50C5 power output, 35Y4
rectifier. Once again, the same radio as version b., using loctal-base
tubes in place of octal. Philco and GE were fond of using loctal tubes.
Note that some radios used a 14B8 converter, which is the same
configuration in a circuit as the 12A8.
The six-tube configuration used the same tube type for both RF
preamplifier and IF amplifier, and the 35 volt heater version of the
output tube. In most cases the RF preamplifier is resistance-coupled to
the RF-converter stage, and the radio used a two-stage tuning capacitor.
Some later versions used movable slug tuning in place of a variable
capacitor. This variation began around 1947, and became more common
during the next decade.
2. Five or six tube AC-DC transformerless radios using 300 ma heaters
wired in series.
These radios were the precursors of the 150 ma. series heater
radios. Some of these radios also included a tuning eye indicator,
typically a 6E5. Total voltage drop of the series heater string was
68-74-82 volts requiring an external voltage dropping resistor of
some sort. These radios often used "ballast" tubes or resistance wire
in the line cord for this purpose.
a. Version using large-base 5, 6, or 7-pin tubes, 1935-50.
6A7 RF-converter, 78 or 6D6 IF, 75 detector-audio, 43 power
output, 25Z5 rectifier. Most of these sets were built before 1938,
although a few manufacturers built them in the early postwar era.
There are more variations on this design than on the 150 ma. heater
designs described above. As noted, some sets had 6E5 tuning eye tubes.
Sets with shortwave often had a 76 triode as a separate local oscillator
for the 6A7.
b. Version using top-cap octal tubes, 1936-1950's.
6A8 RF-converter, 6K7 IF, 6Q7 detector-audio, 25A6 or 25L6
audio, 25Z6 rectifier. This reflects the switch to octal tubes in 1936.
The first three tubes had small top caps for signal grid connection.
The 25A6 is an octal version of the 43; the 25L6 is a 25 volt heater
beam power tube identical, except for heater, to the 35L6 and 50L6. The
25Z5 is a full-wave rectifier (two diode sections), and was usually
connected with the two sections in parallel. However, some
manufacturers, notably Philco, used the two sections to provide voltage
doubling for B+. Radios with voltage doubler power supplies are
AC-only, as a voltage doubler requires alternating current to "pump" the
doubler circuit.
c. Version using single-ended octal tubes, 1939-50's.
6SA7 RF-converter, 6SK7 IF, 6SQ7 detector-audio, 25L6 output, 25Z6
rectifier. Once again, this is a "switch," this time to single-ended
octal tubes. Major circuit difference is in the 6SA7 circuit because of
differences internally between the 6SA7 and 6A8.
This version was generally not built as a "price leader" inexpensive
table radio because of the availabity of 150 ma. tubes that didn't
require a dropping resistor in the heater circuit. It was very often
used as the basis for an upscale AC-DC radio. Some configurations that
you may run across:
1. Shortwave receiver using an additional RF preamplifier,
separate local oscillator, and second IF stage. The 6SK7 was used for
the RF and IF stages, and a 6J5 as a local oscillator.
2. Push-pull audio output, using two 25L6 tubes and a 6J5 as a
phase inverter. This may be combined with the RF-IF additions, above,
and a tuning eye tube (6E5 usually).
Note that use of rectified line voltage gives a relatively low B+, a
major limitation in the transformerless design. The primary market for
a "full house" receiver that had all of these features would have been
the DC service metropolitan areas, particularly New York City, and that
is the general area where most "odd-ball" configurations of
transformerless sets can be found today. In summary, all of the designs
identified in items 1 and 2 above either used the circuit shown in RC-19
example 19-4, or fairly simple variations of the design. There are very
few radios with these tube complements that vary markedly from the
design, which was established around 1932, and licensed to builders
through Hazeltine and RCA patent licenses. In general, the sets that
deviate markedly from the standard circuit are a few Philcos and
Zeniths, and some off-brand sets that may have been marketed through
chain stores with chain store brand names.
3. Postwar AM-FM sets, 1945-up. These were made in two
configurations: separate FM front end, and common front end (i.e, RF,
IF, mixer, and IF amplifiers. There are many variations on both
designs, using 7-pin miniature tubes, loctal tubes, or "hot" octal
tubes. The 6SB7Y was a "hot" 6SA7-type tube capable of self-exciting
oscillation at FM frequencies, and the 6SG7 a "hot" replacement for the
6SK7. The presence of 88-108 MC FM in a radio always means that it is a
postwar set, as this band was not assigned to FM until April, 1945.
Manual RC-19 shows an example of an FM tuner in example 19-9. Many
AM-FM sets "merged" AM capability into the FM tuner design by using a
bandswitch in the RF and converter stages, and by connecting IF
transformer coils for 455KC and 10.7 Mc. in series, the idea being that
the desired frequency will cause one or the other to resonate (high
impedance) and the other will appear as a low DC resistance. The
bandswich would also select which IF fed the AM detector, and which
detector's output was used to feed the audio section. Example 19-9 also
shows both the limiter-discriminator and the ratio detector designs
commonly used in FM-capable sets.
This ends the "most common" AC-DC section. Now we will consider
history, and some of the other designs.
Example 19-1 in RC-19 shows a later battery-operated portable, using
7-pin miniature tubes. This design was built after about 1934,
originally using 5-6 pin tubes in ST-12 bulbs; later, octal or loctal
tubes. This circuit also is the basis for most later battery-operated
"farm" sets, some of which were built as floor consoles. Close study of
the circuit will show its resemblance to the 19-4 example. A very
significant difference is the use of filament tubes, and the method of
using a back-bias resistor (R10 in the example) to develop grid bias
voltage for the output tube. Note also that a different local
oscillator circuit is used for the 1R5. This circuit was often used in
the "All American Five" design as well, and is not unique to the battery
design. Resistance values in example 19-1 have been chosen for
operating with a 67.5 volt B battery; otherwise, the circuit is suitable
for operating with a 90 volt B battery.
Example 19-2 shows a typical three-way portable. The term "three-way"
may seem confusing, when the radio can be operated either from the power
line or from batteries. However, the fact that it could operated from
110 volts DC as well as from AC lines was considered noteworthy when DC
domestic service was common; thus "AC or DC or internal battery" are the
"three ways." Note that a modern ricebox radio operating on an internal
battery or with an AC adapter is not "three way" as it will not operate
from a DC line.
Once again, this is the Hazeltine-RCA standard circuit used in examples
19-1 through 19-5, with specific provisions for the three way feature.
Example 19-2 also shows use of a double-tuned RF preamplifier.
Notable are the use of series connection of the receiver filaments,
provision of a rectifier, and a changeover switch. In practise, many
manufacturers provided a dummy line-cord outlet inside the receiver.
Plugging the line cord into this outlet would mechanically actuate the
changeover switch, placing the receiver on battery operation. When
studying this circuit, note in particular the order in which the tube
filaments are wired, and the use of an 1800-ohm resistor (R14) in the
3V4 filament circuit to provide a shunt-feed balance current. The order
of connection of series-wired heaters and filaments is significant in
series-string sets. In this case, the 3V4 is connected to the high end
to provide grid bias for operating, and the shunt resistor provides some
of the plate and screen currents for the tube. The rectifier circuit
shown is typical, although three way portables may use a 35Z5 or a
selenium rectifier. DC output from the rectifier is around 120 volts,
depending on the rectifier used, which requires a large dropping
resistor to feed the receiver filaments. Note the use of two large
electrolytic filter capacitors, C28 and C29, connected to either end of
the 3V4 filament. Small filament tubes require "clean" DC power, thus
these two capacitors filter out both residual ripple from the half-wave
rectifier and audio-frequency variations caused by varying power draw of
the power tube. This circuit arrangement is critical. If any filament
opens, one or both of those capacitors will charge up to the rectifier
output voltage. Also, the design assumes that the rectifier is part of
the voltage-dropping string, and 1.5V filament tubes are limited in
their ability to handle out-of-tolerance filament voltage.
The circuit shown in figure 19-3 for an AC-operated receiver is the same
as that in figure 19-4, with several upscale features, and resistance
values selected for operation at 250 volts B+ rather than 120. Note
that the circuits for the 6BE6 converter, 6BA6 IF, and 6AV6
detector-audio stages have the same configuration as those shown for
those three stages in figure 19-4. An additional 6BA6 RF preamplifier is
provided for higher gain and better selectivity. A pair of 6AQ5 tubes
provides push-pull output. The second 6AV6 placed ahead of the lower
6AQ5 grid circuit inverts the audio signal for grid drive, with
"approximately unity gain," determined by the tapped grid leak
(470K/8200 ohms) in the top 6AQ5 circuit. This particular circuit is a
classic example of older home entertainment engineering, and there is
much to criticize in its selection over the use of a twin-triode
balanced paraphase using a 12AX7 or a 6SN7. Why was it chosen? Habit,
probably---it was a good choice for 1932.
The main feature of this set which differs from AC-DC configuration is,
of course, the use of a power transformer and a 5Y3 full-wave rectifier.
The configuration of the rectifier circuit was one of the earliest and
most durable circuits in the history of tube-type home entertainment
radio. This later configuration uses a 5Y3 instead of an 80, has larger
filter capacitors (20 mfd rather than 8 or 10 mfd), and a resistor in
place of an inductance between the two filter sections. Older radios
most often used a speaker field coil between the two filter sections,
partly because Alnico magnets were not available until the late
thirties, and partly because inductance at this point compensates for
using smaller capacitance values to get good filtering.
Note the configuration of the screen circuit for the 6BE6 and two
6BA6's. All three screens are connected together. This is poor design,
and likely to cause parasitic oscillations. The circuit in figure 19-4
also shows the screens connected together, but in this instance, there
are only two screen, in stages that operate in opposite phase, so any
coupling between the two stages has a negative feedback effect.
Older radios:
Home entertainment radio began in 1920. KDKA in Pittsburgh generally
has gotten credit for being the first commercial broadcast station. The
two major receiving tubes available at the time with the UX201 and the
UV199, as they were called at the time. The UX201, later revised and
called 01A was a low mu triode. The V99, as the UV199 came to be
termed, was derived from a telephone amplifier triode, developed
during WWI. Several manufacturers built sets, but the most predominant
in the collector market is the Atwater Kent neutrodyne TRF set using
01A's driving headphones. A standard inexpensive set used regenerative
feedback to achieve gain. These were prone to oscillate, squawk, and
whistle, and created no end of radio frequency interference, and rapidly
lost favor, particularly in high-density metropolitan areas.
The first commercially significant superheterodyne receiver was the
RCA "catacombs" receiver of 1924. This set used V99's, a 42 KC IF
frequency, and a headphone-driving-a-horn "loudspeaker." Both the
A-K and the RCA sets required three DC voltage supplies.
The A supply (5 volts DC for 01A, 3.3 volts DC for V99) heated the
filaments. The B supply, typically 90 volts, provided plate voltage.
The C supply, ranging between 9 and 15 volts, and connected as a
negative supply, was used to bias the tube grids. RF gain was
controlled by a rheostat which controlled the filament voltage. These
three voltages were supplied by lead-acid storage batteries, with a
Tungar bulb charger for charging the batteries when the radio was not
being used. All of the RF stages, and the catacombs superhet local
oscillator, were tuned by separate dial knobs.
If this sounds like the definition of a kloodge, it was. I had examples
of both an O1A Atwater Kent and an RCA "portable" (ran on dry batteries)
catacombs set, complete with lead-acid batteries and Tungar charger, at
the end of WWII. These sets sold by the thousands, but were obsolete by
1929, and most of them were discarded when their storage batteries wore
out. Worth noting that "Philco" is a contraction of "Philadelphia
Storage Battery Company." It is also worth noting here that RCA, or
"Radio Corporation of America," was not a separate company until 1929,
but a patent pool and sales company owned by General Electric,
Westinghouse, and AT&T. The phonograph fans will, no doubt, describe
how the Victor Talking Machine Company and Radio Corporation of America
became RCA Victor.
Automatic volume control methods were developed around 1925. AVC, which
is synonymous with the term "Automatic Gain Control" (AGC), allowed sets
to operate at much higher input sensitivity, and to reduce that
sensitivity to prevent overloading in the presence of a strong signal.
Methods of tracking RF stages and a local oscillator operating at some
difference frequency were also developed in the mid-late 1920's. The
final developments needed to build a mains-powered single knob tuning
"modern" superheterodyne radio were filaments capable of working on AC
without developing hum, a suitable high-voltage rectifier, and a tube
with high plate resistance. The first two appeared around 1928 in the
form of the 26 and 71A tubes and the 80 rectifier. While these were not
the actual "first" devices, they appear in almost all of the early
mains-powered radios. The third came about a year later in the form of
the UY224 tetrode, later known as the 24A. The 24 also had another
recent innovation, the indirectly-heated cathode, which allowed the
cathode element of each tube to "float" at a different voltage from the
heater supply DC reference.
Problems with secondary emission from the 24 were "cured," more or less,
by processing the plate material to reduce this emission. This produced
the 24A. However, a more permanent fix was to include a third grid to
"suppress" the reverse current resulting when plate voltage was lower
than screen voltage. The 57 and 58 pentodes were the result. Both have
2.5 volt indirectly-heated cathodes. However, the 58 has a
characteristic known as "variable-mu." Actually, with pentodes, one
considers transconductance, and what "variable-mu" actually does is to
reduce the transconductance as the tube is more heavily biased. The
feature is desirable in circuits with AVC. These pentodes showed up
around 1931. The pentode power amplifier was also introduced around the
same time, with the 47 replacing the 45 in many designed of the 1932-34
era.
The last significant development in tube design for AM broadcast radios
was the development of a single tube with two control grids to serve as
a self-exciting local oscillator and mixer amplifier. The 2A7, quickly
replaced by the 6-volt-heater equivalent 6A7, was the predominant
design, and the 6A7 was used very commonly until after 1940. The 6L7
also was introduced fairly early. This is a mixer that is not designed
to operate as a self-oscillator, and was used, particularly in
communications sets, with a separate local oscillator, until the
1950's.
Availability of a single tube for the superheterodyne oscillator-mixer
function was essentially the death-knell for TRF designs. Another
contemporary development which entered production in 1933 was the 2E5
"tuning eye" tube, which varied a shadow area on a visible target as an
inverse function of the control grid voltage. TRF sets were built into
the 1950's, but are not very common. They tend to be either very cheap
radios for use in metropolitan areas with strong signals or in high end
sets where the broad bandpass allowed "high fidelity" (though the
AM stations actually only transmit a signal that has 5KC as the 3db
half-power point in the modulation).
Availability of components for a vibrator power supply made automobile
sets operating from 6 volts DC practical. There was a wholesale switch
from 2.5 volt heaters to 6.3 volt heaters in 1934. The 2.5 volt heater
series of tubes quickly became obsolete. The switch to 6.3 volt 300
ma. filaments was parallelled by development of a two-diode rectifier
and an output tube with 25-volt 300 ma. heaters, making series string
wiring of the heater circuit practical. These are the 300 ma. heater
transformerless sets described above, which date from about 1934.
Octal-based tubes enter the picture in 1936. Many of the original
designs were built in self-shielding steel envelopes. Metal octal tubes
were built with a flat "button" glass seal, which allowed much shorter
electrode lead connections. Early glass octal tubes continued to use
the older "press" design, with relatively long leads. RF and AF tubes
in the original octal series had small top caps for connection to their
control grids. It was not until about 1939 that single-ended tubes
entered production.
Development of a button seal that could be used with glass envelopes
allowed manufacture of metal-based "loctal" tubes. These entered
production in 1939. At the same time, a cylindrical bulb for glass
tubes also entered production, allowing closer spacing between tubes.
Experimental FM became a commercial broadcast enterprise in 1940. The
original FM band began at 42 megacycles, and production of home
entertainment receivers to receive that band began in 1941. The band
originally overlapped the experimental television band (later channel 1,
48-54 megacycles). The FM band was reallocated to 88-108 megacycles in
the spring of 1945, thus a set with 88-108 capability is postwar.
Another "strictly postwar" feature is the 7-pin miniature tube. The
9-pin miniature followed around 1949.
A few tubes were "survivors" through the 1928-50 period. The standout
among these is the 80 rectifier, which was still being used in new
production in the mid-1950's. The 5Y3GT which replaced it is nothing but
an octal-based version of the 80. The 2A3 and 45 power triodes, as well
as the less-common 6A3 were all used from the early 1930's until well
into the 1950's. There remains today something of a cult that
believes that these triodes are the only audio power tubes worth
considering. All of these tubes use filament cathodes, and the most
practical circuits for using them required a separate filament winding,
elevated to the 40-60 volts needed to bias these tubes near cutoff.
Beam power tetrodes were introduced as octal tubes, although the 807
(very rarely seen in the home entertainment market) continued to use the
older large 5-pin base. The principal beam power tetrodes were the 6L6,
6V6, and 25/35/50L6. The 6L6 in a push-pull circuit required more
current than a 125 ma. 80 could provide, and presence of a pair of 6L6's
with a bigger rectifier means a "high-end" set. Push-pull 6V6's could
be supplied by an 80 and provide very adequate audio power of good
fidelity to the open-mounted loudspeakers used in virtually all home
entertainment equipment until the mid-1950's. Generally, a push-pull
power output stage, using any pair of triodes, beam tetrodes, or
pentodes, means a quality set with other desireable features, low hum,
and good sensitivity.
The various oscillator-mixer tubes used can affect a radio's ability to
perform, particularly on shortwave bands. Historically, the first such
tube was the 7-pin 2A7/6A7, followed by the octal-based 6A8, all using
the same pentagrid construction and circuit. These operated well on AM
broadcast, but had severe problems dealing with higher frequencies.
While they were commonly used (particularly the 6A8) into the late
forties, they generally give very poor performance on shortwave bands
above 10-15 Mc (40 meters). The 6L7 was developed as a mixer to be
driven by a separate local oscillator to overcome some of the
limitations of the 6A8. The separate-section 6J8 and 6K8 were developed
to provide better high-frequency performance without need for a separate
local oscillator. These tubes can operate well up to about 25 mc. The
loctal versions (7J7, which is the same as a 6J8, and the 7S7, which is
a higher-gain 7J7) would operate over 30 mc. (10 meters.). The final
version was another layout of the 6-grid "pentagrid" design, the 6SA7.
The 6SA7 would operate, with the inner section as an oscillator, up to
about 27 mc. The 6SB7Y octal, 6BE6 7-pin miniature, and 7Q7 loctal all
would operate satisfactorily up the commercial FM frequencies. A common
method for getting better high-frequency performance was to use a
separate local oscillator with a 6L7, 6SA7, or 6BE6. Glow-discharge
voltage regulator tubes were commonly used in high-end communications
designs to regulate B+ to the local oscillator, giving improved
stability to the circuit. For serious shortwave listening, you should
avoid a set with a 6A7 or 6A8, and consider one with a separate local
oscillator (typically a 6C5, 6J5, or 6C4) and a voltage regulator tube.
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From: vancleef@netcom.com (Hank van Cleef)
Subject: Rec.antiques.radio+phono Radio Spares and Services(FAQ: 5/9)
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Archive-name: antiques/radio+phono/faq/part5
Rec.antiques.radio+phono Frequently Asked Questions (part 5)
Revision Date Notes
2.0 11-1-94 Revised version from Aaron Field. (this version was
previously posted to the newsgroup).
2.1 1-7-95 Added some material to Aaron's list.
2.2 7-8-95 Removed Aaron Field's address as he apparently no longer
has an Internet account at the address listed. Our thanks to Aaron for
having done the work to get this list started.
3.0 10-95 Did a whole bunch of work on the list. Added material on
tubes and schematics.
3.1 Nov 19, 95 Move from part 4 to part 5
3.2 4-96 Add new sources, tube buyer notice
Part 5 - Sources of materials, supplies, and bibliography for antique
electronics
------------------------------------------------------------------------------
The most frequently asked question is "where can I get vacuum tubes?"
TUBE SELLERS:
Antique Electronic Supply
6221 S. Maple Ave
Tempe, AZ 85283
Tel: 602-820-5411
Contact Daily Electronics
P.O. Box 5029
Compton, CA 90224
Tel: 800-346-6667 (Orders)
Tel: 213-774-1255 (Tech)
Don Diers
4276 North 50 Street #SC3
Milwaukee, WI 53216-1313
DNF
6690 7 Mile Road
South Lyon, MI 48178
Electron Tube Enterprises
Box 8311
Essex, VT 05451
Tel: 802-879-7764
Fair Radio Sales
Lima Ohio
Phone: 419-227-6573
Kirby
298 West Carmel Drive
Carmel, IN 46032
Lippert N61W
15889 Edgemont
Meno Fls, WI 53051
New Tube Co.
P.O. Box 202
Middle Village, NY 11379
Tel: 718-894-2131
Quest Electronics, Inc.
5715 W. 11th Avenue
Denver, CO 80214
303-274-7545 Voice
303-274-2317 Fax
Steinmetz Electronics
7519 Maplewood Ave
Hammond, IN 46324
Tel: 219-931-9316
Michael C. Marx
SND Tube Sales
5389 Ville Rosa Lane
Hazelwood, MO 63042
314-770-0119 phone
314-770-9448 fax
email: tubes@i1.net
(furnished by Dan Schoo)
(Note, this is not a supplier, but a buyer of old tubes. I'm copying
the posting slightly trimmed down).
-----------------------------------------------------
I am the Purchasing Agent for Antique Electronic Supply in Tempe, Arizona. We
purchase tubes (or valves, as the English call them!) for resale. Anyone who
is interested can contact me at tubes@crzyone.com, and I can send them via
email the current bid list for tubes we have a need for and our current bid
prices.
For further information, email me at the above address or call (602) 820-5411.
If you want to check out the web sites for a couple of tube manufacturers, try:
http://www.svetlana.com for Svetlana Electronic Devices
http://www.rell.com for Richardson Electronics.
Edward C. Bender
-----------------------------------------------------
Q: Where can I get tubes, electronic parts, knobs, dial lenses,
grille cloth, schematics, literature, refinishing supplies, etc.?
A: The following suppliers carry a variety of merchandise for
collectors and restorers of vintage radio/phono/TV/jukeboxes. Catalogs
or inventory lists are available from all of them. Following this list
is a directory of commonly needed items, with additional sources.
1. Antique Electronic Supply, 6221 S. Maple Ave., Tempe, AZ 85283,
(602)820-5411: Great source for tubes, components, restoration
supplies, books, etc. If you're new to the hobby, start with
the AES catalog--it's indispensible!
2. Puett Electronics, P.O. Box 28572, Dallas, TX 75228,
(214)321-0927: Incredible supply of literature and service
data, also some parts. Good source for collectors of
E.H. Scott and McMurdo silver radios.
3. Play Things of Past, 3552 West 105th St., Cleveland, OH 44111,
(216)582-3094: Plenty of hard-to-find parts for the earliest
radios, including rare tubes. (Probably the best source for
original parts on 1920's sets.) Lots of literature as well.
Excellent catalog.
4. Old Tyme Radio Company, 2445 Lyttonsville Rd., Silver Spring,
MD 20910, (301)585-8776. Tubes, vintage parts, radios,
test equipment.
5. Great Northern, P.O. Box 17338, Minneapolis, MN 55417,
(61) 727-2489: Lots of stuff for collectors of Zenith radios--
parts, literature, T-shirts, service data.
6. Vintage TV and Radio Supply, 3498 W. 105th St., Cleveland,
OH 44111, (216)671-6712: Nice selection of books, tubes,
knobs, components, refinishing supplies, etc. Much better
knob selection than AES (#1 above). Good catalog.
7. Wade's World of Knobs (Wade and Joe-Ann Terrell), 7109 E. Arbor Ave.,
Mesa, AZ 85208, (602)830-7849: Reproduction plastic knobs and dial
lenses, etc.
8. Antique Radio Labs, R1, Box 41, Cutler, IN 46920, (317)268-2214:
Limited selection of various parts and literature.
9. Don Diers, 4276 North 50th St., Milwaukee, WI 53216-1313:
Nice selection of tubes and vintage parts. Tons of caps!
Fun to read catalog!
10. Triode Electronics, Box 578751, Chicago, IL 60657, (312)871-7459:
Jukebox needles, cartridges, tubes, other parts.
11. A.G. Tannenbaum, P.O. Box 386, Ambler, Pa. 19002;
Tel: 215-540-8055: Vintage parts and literature, test equipment.
NOTE: Tannenbaum has moved. New address per their telephone recording
is PO
Additional sources are contained in the following directory of
commonly needed items. The list is currently geared mainly towards
radio, but phono/TV/jukebox collectors should find useful sources
here as well. The sources listed above are referred to by number.
Books--
Best source for currently published books on collecting and restoring
radio/TV/phono etc. is #1! For vintage literature, see "Literature"
listing below.
Capacitors--
#1, #6, #10 all have good selections. #10 may be the best.
Custom rebuilds on single or multi-unit can caps are available from:
Frontier Electronics, 403 S. McIntosh St. or Box 38,
Lehr, ND 58460, (701)378-2341. Price list available.
Coils--
#1,3,4,6,8,9 all have various coils, chokes, and transformers,
both originals and replacements. (Try #3 first for original
1920's and 30's stuff).
Decals--
Decal reproductions of the following logos are available from
#1,4,6 (and probably others): Philco, Atwater Kent, Zenith,
Stewart-Warner, RCA, Stromberg-Carlson, Admiral, Emerson, GE,
FADA, Garod, DeWald, Belmont, Sonora, Magnavox Lion (for horn
speakers).
Dials--
Reproduction tuning dials available from:
Antique Radio Restorations, 635 S. Lincoln Ave.,
O'Fallon, IL 62269, (618)632-7423. (AK, RCA, Zenith, Philco)
Also try #1,2.
Dial covers--
Reproduction dial covers custom made from broken cover or tracing:
a. #7
b. Doyle Roberts, HC-63 Box 236-1, Clinton, Arkansas 72031,
(501)745-6690.
c. Old Time Replications, 5744 Tobias Ave., Van Nuys CA, 91411,
(818)786-2500.
Limited selections of original dial covers available from #1,2,4,6.
Dial pointers--
#6 has a few generic replacements if you can't find an original.
Grille cloth--
a. Good selections from #1 and #6. Sample cards available.
b. John Okolowicz, 624 Cedar Hill Rd., Ambler, PA 19002,
(215)542-1597: "Deluxe Replica Grille Cloth" (Philco,
Emerson, Scott, Zenith).
Knobs--
Best selection of reproduction knobs from #6 (check here first
for clock radio knobs) and #7. #1 not bad for Zenith and Philco.
Most suppliers say "many available, send us your request".
Lamps--
#1,3,6 and 9 all have good selections.
Literature--
#2 and #3 have impressive archives of vintage radio literature,
with titles listed in their catalogs. #1 and #6 have reprints
of popular service manuals and repair data (AK, Philco, Radiola,
Zenith). Also see "Schematics and Repair Data".
Periodicals--
a. "Antique Radio Classified" (monthly), PO Box 2-V32, Carlisle,
MA 01741, (508)371-0512: Classified ads, radio supplier ads,
articles, meet announcements.
b. "The Old Timer's Bulletin" (quarterly, with membership in
Antique Wireless Association), dues $12.00. Contact AWA, Box E,
Breesport, NY 14816. High quality publication chock full of
articles on all areas of vintage radio, including broadcast,
communications, telegraph, TV, etc.
c. "The Radio Collector" (monthly), PO Box 1306, Evanston,
IL 60204-1306, (708)869-5016: published by Marc Ellis, antique
radio columnist for "Popular Electronics" for many years.
Regular features include repair and restoration advice, vintage
book reviews, company chronicles, Q&A, classifieds. $20.00/yr.
Highly recommended.
d. "Radio Age" (monthly, with membership in Mid-Atlantic Antique
Radio Club), dues $20.00. Contact MAARC, Roy Morgan, PO Box
1362, Washington Grove, MD 20880. "Radio Age" was its own
publication until its recent merger with the "MAARC Newsletter".
e. Electric Radio (monthly). Box 57, Hesperus, CO 81236. Published
by Barry and Shirley Wiseman. This is an amateur radio
magazine. Editorial policy is "Our primary interest is in
"... vintage equipment/operating with an emphasis on AM, but
articles on SSB and CW are also needed."
f. There are many radio clubs across the US, each with its own
newsletter!
Refinishing supplies--
#1 and #6 supply all manner of chemicals (fillers, polishers,
lacquers, etc.) for refinishing both wood and plastic cabinets.
Repair and restoration services--
There is probably a collector's club near you that can steer you
towards an individual in your area who works on vintage equipment.
Otherwise, if shipping your radio is an option for you, try the
following:
a. For Your Listening Pleasure, 368 Clinton St., Binghamton,
NY 13905, (607)797-0066. Four levels of restoration are
available, from "working order only" to "museum quality"!
b. #3 and #4 do repairs--not sure about cabinet restorations.
c. Sunrise Services, 2343 Ballycastle, Dallas, TX 75228,
(214)328-4249. Radio cabinet refinishing, wood or plastic.
d. Check "Antique Radio Classified" for countless ads for this
type of service!
Loudspeaker reconing:
There have been several postings identifying the following as
rebuilders of old loudspeakers.
Mr. Richard Stamer
Sound Remedy
331 Virginia Ave.
Collingswood, N.J. 08108
609-869-0238
Mr. Hank Brazeal
103 N. Lake Point Ct.
Crossville, Tenn. 38555
615-456-2529
Speakerworld
2000 Warm Springs Ct. #6
Fremont, Cal. 94539
510-490-5842
Sound Remedy
331 Virginia Avenue
Collingswood, NY 08108
609 869 0238
Schematics/repair data--
Most schematics on vintage radios come from either the
Rider's Perpetual Troubleshooter's Manuals (earlier sets)
or the Howard Sam's Photofacts (post-war sets). These are
available in many public libraries. Otherwise, the following
suppliers offer schematics at reasonable rates (if you can
provide them with a model number): #1,2,4,5. If you don't
have a model number but can provide the tube #'s and layout,
for an extra fee they can usually find the right schematic.
See also "Literature".
Howard W. Sams began publishing repair data in 1947. Don't look for
schematics, etc. of prewar electronics in Sams.
Rider reprinted manufacturers' repair information, and you should look
for "family resemblances" between the radio you have and radios of the
same make---Rider may have published repair data for only one or two of
a large family of model numbers that are nearly identical. Also keep
in mind that many smaller radios built after the mid-thirties were
built to standard Hazeltine/RCA designs under license, and you may not
need a specific schematic for your set).
Tubes--
A complete list of tube suppliers would be an incredible headache
to compile. Just about all of the suppliers listed at the beginning
of this directory have tubes, and it is unlikely that you would
be unable to get what you need from at least one of them. The ones
that have their inventory conveniently listed in their catalog are:
#1,2,3,6,9. Prices vary.
Some other suppliers for various things:
Local sources. Take a look in the Yellow Pages, and check out any
place that advertises under "radio repair." You may find that your
area has an old-time shop or two that does repair work on old
electronics. Don't ignore possible local sources---a few phone calls
will generally lead you to one, even if you don't identify it from the
Yellow Page listings immediately.
Mouser
2401 Highway 287 North
Mansfield, Tex. 76063
800-346-6873/817-483-4422
Mouser is a "modern components" distributor with a big catalog. They
have distribution centers in California and New Jersey as well. While
they do not stock antique-specific items, they are a good source for
resistors, capacitors, wire (modern only) and a host of other useful
items.
MCM Electronics
650 Congress Park Dr.
Centerville, Ohio 45459
800-543-4330
Most of MCM's inventory is oriented toward modern devices, but some of
their items can be used in old radio restoration. They also stock a
large inventory of Japanese and Motorola transistors.
The following advertise regularly in Electric Radio (a magazine for old
amateur radio equipment)
Fair Radio Sales
PO Box 1105/1016 E. Eureka St.
Lima, Ohio 45802
419-227-6573
Primarily military surplus, plus some test equipment and vacuum tubes.
Purchase Radio Supply
327 East Hoover Avenue
Ann Arbor, Mich. 48104
313-668-8696
(Not specific as to what they carry, but worth investigating---they
state they've been there 60 years and specialize in old items).
On magnetic components (coils, RF-IF transformers, power transformers,
chokes), you are faced with several choices, depending on what you need.
Antique Electronic Supply carries a selection of iron core magnetics
and a few other items, primarily for smaller radios. Several suppliers
offer interstage transformers for 1920's sets. If you need a power
transformer you may need to adapt mechanically and/or electrically.
You will need to know the exact dimensions of mounting holes, chassis
cutouts, space available for mounting, etc. You will also need to know
the voltages and current requirements of secondary circuits. If you
have some idea what substitutions you can make, calling around may
produce a very good substitute. For a price, there are several
transformer shops that will build you a new transformer to your
specifications.
Universal-wound coils (i.e., wound zigzag on forms) are difficult to
replace. Fortunately, they don't often give trouble---main problem is
antenna coils zapped by lightning. There are very few shops today who
are equipped to wind universal-wound coils. Some electrical adaptation
of NOS (new old-stock) items is possible in some cases.
If you are dealing with a radio that needs magnetic components or has a
physically-unrepairable tuning capacitor, you may have a parts radio.
Test equipment:
Most test equipment comes from sellers at hamfests. Fair Radio Sales
has several items of test equipment for sale. One source that
specializes in an interesting variety of test equipment, as well as
some old radios and parts furnished the following self-description:
----------------------------------------
W.J. Ford Surplus Enterprises
We have a wide assortment of surplus electronics for sale. Check out
our electronic listings at:
http://infoweb.magi.com/~testequi/
Our lists are regularily updated as new stock comes in.
W.J. Ford Surplus Enterprises
P.O. Box 606, Smith's Falls, Ont. K7A 4T6
phone: (613)283-5195
fax: (613)283-0637
email: testequi@magi.com
check out our home page at http://infoweb.magi.com/~testequi/
--------------------------------------------
Bibliography:
The following books are relevant to old radio design, repair, and
history.
1. Loomis, Mary Texanna. "Radio Operating and Theory." Several
editions, 1925-30. Washington D.C., Loomis Publishing Co.
2. Ghirardi, Alfred A. "Radio Physics Course" At least two editions,
1931-33. New York, Murray Hill Book Co.
3. Terman, Frederick E. "Radio Engineering." Three editions, 1932,
1937, 1947. "Electronic and Radio Engineering" was published as a "4th
edition" in 1956, but covers different topics. New York: McGraw-Hill.
4. Terman, Frederick E. "Radio Engineer's Handbook." 1st ed. New
York: McGraw-Hill, 1943.
5. Langford-Smith, F. "Radiotron Designer's Handbook." Four editions,
1934, 1935, 1940, 1952. Sydney, Amalgamated Wireless Valve Company
Pty. Ltd.
6. Hund, August. "Frequency Modulation." New York, McGraw-Hill,
1942.
7. Rider, John F., ed. "Perpetual Troubleshooter's Manual." 23
volumes, 1928-53. New York: John F. Rider Publishing.
8. Howard Sams "Fotofacts." Issued as folders, beginning in 1947.
Indianapolis: Howard Sams Publishing.
9. There are several works available through Antique Electronic Supply,
either recent items or reprints of old material.
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From: vancleef@netcom.com (Hank van Cleef)
Subject: Rec.antiques.radio+phono Cosmetic and Cabinet Questions(FAQ: 6/9)
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Date: Sat, 19 Oct 1996 23:15:31 GMT
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Archive-name: antiques/radio+phono/faq/part6
Rec.antiques.radio+phono Frequently Asked Questions (Part 6)
Revision Date Notes
1.0 Oct. 15, '95 New section
Part 6 - Cosmetic and cabinet finish questions
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FAQ editor: Hank van Cleef. Email vancleef@netcom.com
This is a regular posting of frequently-asked questions (FAQ) about
antique radios and electronic phonographs. It is intended to summarize
some common questions on old home entertainment audio equipment and
provide answers to these questions.
This section discusses some of the methods that can be used to clean and
restore items in acoustic phonos antique radios, and other items. While
the internal construction of phonos may be quite different than that of
electronic devices, many of the cleaning issues are quite similar.
Almost any old device requires a fairly standard cleanup involving
removal of dust and dirt, internally as well as externally. The first
step in restoring an harmonium (reed organ) or a piano, as well as a
phonograph, music box, or radio, is to clean the item thoroughly, inside
and out, and assess its condition. Very often, all that is needed is a
good vacuuming, with the help of some small paintbrushes to loosen dirt,
and a soap-and-water cleanup. Clockwork mechanisms, small electric
motor mechanisms, and electric phono turntable, wire recorder, and
similar mechanical transport mechanism generally need to have old
"petrified" lubricants cleaned off, and reassembly with new lubricants.
Cabinet restoration depends on the method of cabinet construction and
finishing. Items built in the 19th and early 20th centuries generally
had wood "furniture" cases, finished with a shellac process. The
introduction of synthetic varnishes in the 1920's meant a rapid change
to use of synthetics for wood finishes, and shellac finish on a home
entertainment device becomes rare through the 1925-40 period. Post WWII
wood finishes are most commonly one of the urethane synthetics.
Plastics that could be formed by casting and injection molding processes
became available at the end of WW I, and many home entertainment devices
made in the 1920's have visible parts made of "Bakelite," a phenolic
resin with an inert filler that can be injection molded. By 1940, there
were a variety of thermoplastic (i.e., melts when heated) and
thermosetting (i.e., cures under heat and does not remelt) resins were
commonly used in construction of molded radio cabinets, knobs, and
decorative trim items. Many of the plastics used in the later pre-WW II
period were not stable over long periods. Ultraviolet from strong
sunlight and heat above human body temperature would accelerate
distortion and discoloring, for which there generally is no repair other
than replacement of the affected part. Items in good condition should
be cleaned up and positioned where they will not be subjected to strong
sunlight or heat.
Various metals are used both in internal construction and in cabinetry.
Painted steel plates and cabinets are commonly found. Also stamped
brass decorative parts. One very common process was to use steel and to
electroplate it with a brass finish. Die cast white metal parts are
commonly found. The zinc alloys used in the 1910-35 period produced
excellent parts, but are subject to aging and corrosion breakdown.
Typically, they will become larger, then become extremely brittle and
crumble. Once again, the only "repair" solution is replacement of the
affected part. There is a long-standing myth that white metal parts were
made of "floor sweepings" and scrap, and the term "pot metal" is
sometimes used in the US to denote the material. This is not accurate.
Zinc precision die casting technology uses specific alloys and
processes, and produces excellent results. Some manufacturers used
die-cast or sand-cast aluminum alloys after the mid-1920's. These
should not be confused with zinc alloys. Die casting processes for both
zinc and aluminum produce high dimensional accuracy, but require
creation of an expensive metal mold set, so are generally associated
with high-volume parts. The tooling required for sand casting is much
simpler and less expensive, but the as-cast parts require machining of
critical dimensions.
This is a very cursory overview of materials and processes, and the
reader who wishes more information should search out and study some of
the literature written for engineers and crafts people who work with
these technologies. In particular, "Machinery's Handbook" and (in the
US) the SAE Handbook (Society of Automobile Engineers) have extensive
information on metals and manufacturing processes.
Your FAQ editor has some strong feelings about some of the techniques
for cleaning and restoration that have been discussed on various
newsgroups. There is no question that many restorable items have been
ruined beyond repair by use of inappropriate chemicals and cleaning
methodologies. Beyond this there are considerations of "kitchen
chemistry." Almost any solvent or process has safety considerations to
consider. And almost any solvent or process will damage something in a
device. You may want to use it over here on this metal part, but if you
get it on that plastic part or electronic component, in may destroy it.
Additionally, there are issues of fire hazards, fumes, violent reactions
with other chemicals, and safe storage to consider. Know your products,
and know your processes. A kitchen is a place for food preparation, not
chemistry experiments or industrial processes. Be very careful to keep
solvents where they cannot contaminate foods or anything used for food
preparation. Store chemicals separate from food items, and away from
the inquiring hands of small children. Also keep in mind that many of
the preparations sold in grocery stores for kitchen cleaning purposes
are, in reality, very strong chemicals, and may have very little
information on the chemical content or processes. When writing this, I
checked a can of Dow brand oven cleaner. It acknowledges 4% sodium
hydroxide as an active ingredient, and gives a litany of safety
precautions in use. This stuff is more violent than most of the
industrial cleaning processes I've used. Many of the spray can cleaning
products are very easy to use----just spray them on your valuable
antique and watch it dissolve before your very eyes. Remember that
these are proprietary products, and while the labels may disclose a few
"active ingredients," it is often not all that is in there that will
wreak havoc. There is a steady stream of notes in the antique groups
from people who tried a spray can kitchen product and discovered, too
late, that it took markings, finishes, etc. off along with the dirt.
There are two manufacturers who make chemical products specifically for
use around electronics equipment. Caig Laboratories makes "DeOxit,"
which is considered by many people to be about the best contact cleaner
around. They make a number of other chemical products for various
electronics uses, and provide good and specific application and use
notes for their products. GC Electronics, formerly General Cement, make
a variety of products for various uses. These include a good electronic
coil dope, a chemical wire insulation stripper for stripping the enamel
from magnet wire, and a variety of cleaning products and adhesives.
One "easy cleaning" method that gets tried regularly is use of a
household dishwasher to clean things. Don't do it. Almost all
dishwashers use high temperatures in their washing cycle, and the
detergents used are a strong caustic solution. They may wash dishes
well, but for other cleaning, have almost all the attributes and
drawbacks of a hot caustic tank (see "lye," below) with few of the
virtues. I've had the unpleasant experience of spending a day with
precision machine tools reworking the castings in an automotive power
steering pump that were put through a good household dishwasher.
General purpose solvents that are generally mild and easy and effective
to use are:
1. Water, with or without soap. Water is actually the most universal
solvent. A little bit of soap or detergent will increase its ability to
wet the surface. More soap will make an alkaline solution. Safe on
most things, but may dissolve inks used on dial markings, and should be
used with care around electronic components, particularly iron core
chokes and transformers. One of the better detergents to use is a
generic-type dishwashing detergent such as Octagon brand.
2. Household ammonia. This should be the clear non-sudsing type, with
no additives like lemon sent. Straight ammonia is a strong alkali, and
will dissolve shellac very quickly. A mild ammonia solution generally
does a good job of dissolving dirt on painted and metal surfaces. A
plain ammonia solution without additives will dry without leaving a
residue, and may be preferable to a soap/detergent solution for many
applications where a thorough water rinse is not used.
3. 3M adhesive cleaner (an automotive product). This is a petroleum
product sold for removing adhesive residue, road oil, etc. from
automobile painted surfaces. It is safe on most plastics. Excelle]]>