Understanding Antique Radios

April 1st, 2008

Phil Nelson runs Phils Old Radios, a member of our Hall of Fame, and a great resource for information on antique radios.

You’ve just acquired an old radio, but apart from the manufacturer’s name on the front, you don’t know a blessed thing about it. Learning more about your radio may satisfy your curiosity, or it may serve a practical purpose such as helping you get repair information. Here’s how to go about identifying an antique or vintage radio, and then how to decide if it’s playable.

Identifying Radios By Manufacturer, Name, and Model Numbers

Zenith TransOceanic6G601M

Tens of thousands of different radio models were manufactured over the decades, in the US alone. Many thousands more were manufactured worldwide. Most of the radios sold over those decades are not very interesting. For every rare and unusual radio, there were thousands of cheap and common radios.

The normal way to identify a radio is by manufacturer and model number (for example, “Zenith 7G605″ or “Philco 42-350″). Model numbers can include any combination of letters and numbers, and they may be long or short, although most are from two to six characters in length. There is no standardization whatsoever for model numbers. Every manufacturer was free to make up its own scheme, and often a given manufacturer would change its numbering scheme over the years.

Model numbers are often printed on a paper label attached to the back, inside, or bottom of the radio cabinet. The label usually contains other information, such as a serial number, tube diagram, or even a complete schematic diagram. The model number may also be printed somewhere on the cabinet itself. On my Zenith TransOceanic H500, the number is printed in white ink inside the hinged back cover.

Most radios also list various patent numbers. These are pretty useless for identification, because virtually all radio makers licensed several technology patents from other manufacturers, and they were required by law to disclose those patent licenses. If you look at a bunch of old radios, you’ll see that many of them list exactly the same patents.

Wooden Philco 90

Patent notices often include dates, but those do not tell you when the radio was made. They only indicate when the patent was originally granted, which could be many years earlier. So a patent date merely tells you that the radio could not have been made before that date.

Some radios have a name in addition to (or, occasionally, instead of) a model number. For instance, my Crosley F5-TWE was known as the “Musical Chef,” and that name is actually printed on the front of its cabinet. Hundreds of different names were used over the decades—everything from the predictable (“Globetrotter”) to the alliterative (Zenith “Zenette”) to the fanciful (“Phantom Baby”). The name may be handy if a collector guide happens to list your set by name instead of by model number.

Resources for Identifying Your Old Radio

Collector books list thousands of radios, often with approximate values. The Slusser (formerly Bunis) collector guide is one of the most popular, although it’s by no means the only show in town.

Technical service publications are another great source of information. These include Rider’s, Sams Photofacts, Most Needed Radio Diagrams, and so on. Technical references were published for radio repair shops and they are still to be found in many public libraries.

Radio collectors may be able to help. If you haven’t already done so, look for a radio collector club in your vicinity. The Antique Radio Classified website has an extensive list of clubs in North America.

Newsgroups. If there’s no club nearby, another possibility is the USENET newsgroup rec.antiques.radio+phono. Although that group is concerned mainly with technical discussions, some members are willing to help with identifications.

Websites. When I launched my site in August, 1995, there was only one other website like it in the world. Now there are dozens, with more appearing all the time. A radio website might happen to show your radio, or perhaps its webmaster is willing to field your question. Speaking of which—if you’ve tried all these channels and struck out, feel free to send me some email. I usually have time to make a quick scan of my collector books to see if a radio is listed.

Other Identifying Features

Emerson 558 tube portable

Even if your radio has lost its label or logo, or perhaps never had them to begin with, you can still identify the set, though it may take some detective work. Here’s some things to look at:

Component markings. If the outside lacks identifiers, the inside may still hold clues. Look inside the chassis—if you see the same manufacturer’s name stamped on all the tubes and other components, that’s a tipoff. On the other hand, it’s not unusual to see a mixture of brand names on components. Many manufacturers got components from other suppliers. And radios that were repaired over the years often have a random assortment of replacement parts under the hood.

Cabinet design. Often a strong indicator of when a radio was made. The very earliest radios were typically bare components mounted on a board. Somewhat later, many were housed in comparatively plain wooden or metal boxes. By the late 1920s, some were housed in elaborate cabinets designed to look like “real furniture” instead of electronic gear. Cathedral and tombstone style wooden cabinets were most popular during the 1930s. The 1940s were the heyday of “Machine Age” and other design trends.

Cabinet materials. 1920s radios were typically housed in wood, although some tabletops came in rather plain metal cabinets. Bakelite and Catalin were the most popular synthetic materials during the 1930s and 1940s. Other early plastics, such as Plaskon and Beetle, predated the flood of new synthetics that came along during the 1950s. Wooden cabinets were used during all periods from the 1920s to the present.

Plastic Zephyr 1

Dial Markings. The band and frequency markings on the dial can tell you something about a radio’s age. The earliest 1920s radios did not show any station numbers; instead, their knobs were marked with numbers from 0-100 or sometimes nothing at all. If your radio has a band marked Police or Aircraft, it was probably made before World War II; those frequencies are no longer used for such communications. Shortwave radio was common from early days, but FM broadcasting wasn’t developed until the 1930s. The FM band frequencies were changed after World War II, so if you have a radio that tunes FM from 42-50 megahertz rather than the modern 88-108 megahertz band, you know it was manufactured before 1942. A radio that has FM stereo was made in the late 1950s at the earliest. Civil Defense (CD) markings on the AM dial at 640 and 1240 kilohertz indicate that the radio was made between 1953 and 1963.

Tubes. The very oldest radio vacuum tubes looked more like light bulbs and had screw-type connections. Most 1920s tubes had glass envelopes and large bakelite bases with four or five pins. 1930s and 1940s tubes typically had glass or metal envelopes and six, seven, or eight pins. Locking (“loktal”) metal bases were used for a few years in the late 1940s. They were superseded in the 1950s by all-glass “miniature” tubes with very thin pins. Keep in mind that different tube types overlapped. For example, some radios continued to use loktal or older tube types into the 1950s. However, if your radio uses glass miniature tubes, you know it must have been made after the end of World War II, and was likely made in the 1950s or later.

Transistors. Transistors were introduced in 1957, so every transistor radio is dated after that time. Transistors didn’t become common until the 1960s.

Before Turning On Your Radio

Buick trans-portable transistor

If you just brought home an antique radio, you’re probably dying to play it immediately. That could be an expensive mistake unless the set was professionally repaired before you bought it. If the radio has a short circuit or defective component, turning it on could further damage the set or even start a fire. You should always check an unknown radio for gross problems before you turn it on—otherwise, “firing it up” might be a sadly literal experience!

A few problems can be spotted visually. For example, if the power cord is broken, cracked, or frayed, you must replace it before trying to plug in the radio. Some other problems can be spotted by looking at the chassis. (This is the metal box inside the cabinet, upon which other components are mounted.)

Some radios have backs and others don’t. If the radio has a back, you’ll need to remove it to inspect the components (tubes, etc.) on top of the chassis. The cabinet back is usually attached with a handful of small screws or clips. As you remove it, be careful not to break any antenna wires that may be attached. Some newer radios will have an integrated connector for the power cord, which unplugs the cord from the chassis as you (gently!) remove the back.

After the back has been removed, you should look for gross problems include missing or broken tubes, and anything else that’s obviously absent, broken, disconnected, fried, or massively corroded. If you see any of these signs, count on repairing the set before you power it up.

In almost all cases, the radio’s electronic components—tubes, capacitors, resistors, etc.—will look exactly the same whether they have failed completely or they are working perfectly. When a radio is turned off, a dead tube looks just like a good one. A shorted capacitor looks just like a good one, and so on.

Zenith Y724 Bakelite

Many experienced restorers would not bother trying out the radio at this stage. Instead, they would remove the chassis and routinely replace most or all of the old capacitors. If you’re a beginner, you won’t learn anything useful by looking under the chassis. And plugging in the radio outside the cabinet will only increase your risk of getting an electrical shock. But you can read all about this process in my article Replacing Capacitors in Old Radios. Whether you want to take this cautious approach is up to you.

Let’s assume that either you have finished the capacitor replacement or you’re willing to risk firing up the radio as-is. Either way, most restorers will power up the radio using a gadget called a variac which lets you slowly increase the voltage, watching for any danger signs along the way. If you don’t have a variac, you can use an inexpensive homemade substitute. Our Dim-Bulb Tester page gives directions on building and using such a device. In addition to increasing the voltage by increments, a dim-bulb tester can also warn you of short circuits in the radio’s power supply.

If you don’t have either one, you can simply turn on the power switch and cross your fingers, but I advise against that practice, for all the reasons given above. Once the voltage has been increased to full power, turn the volume control up about one-third of the way and tune the radio dial to a strong local station. Within about fifteen seconds, the tubes should begin to glow with a faint orange color. (Exceptions are metal-cased tubes, which have an opaque covering, or very-low voltage tubes such as those in old Zenith TransOceanics.)

Watch closely for anything unusual as the radio warms up. A slightly hot smell is normal, especially if the radio is dusty, but a strong burning smell indicates trouble. The same goes for any sparking sounds or smoke, which usually indicates a serious problem. If the radio plays normally, take a moment to congratulate yourself, then turn it off until you have time to replace the capacitors (see above).

If you hear a loud humming sound that does not change when you turn the volume control, that is caused by failed filter capacitors in the power supply. The radio will not work until you replace them.

If it Sounds OK, Can I Use It?

G500

You can play an unrestored radio all you want . . . if you don’t mind the risk that it will fail at any time without warning. In my experience, most unrestored radios will conk out—typically with one or more failed capacitors—before long. And if you go in to replace that failed capacitor, it’s only a short time before the next one will fail, and so on.

To get a radio that is safe and reliable to use every day, it’s best to replace all of the old capacitors at once. If you choose not to do that, I strongly advise that you never leave the room while the radio is playing, or leave it playing overnight. It’s just not worth the risk. A few unrestored radios might play for a long time without problems. Others can start on fire—it has happened to me!

Images in this article appear in the following order:

(All images courtesy Phil Nelson of Phils Old Radios)

1. Zenith TransOceanic 6G601M
2. Wooden Philco 90
3. Emerson 558 Tube Portable
4. Plastic Zephyr 1
5. Buick Trans-portable Transistor
6. Zenith Y724 Bakelite
7. Zenith TransOceanic G500

Do you have an article you’d like us to publish as a guest column in The Collectors Weekly? Let us know.

34 comments so far

  1. Jim Tripp Says:

    I love your site. The guest column by Phil Nelson “Understanding Antique Radios” is very useful to beginners to help them find out more about their new found antique radio. However, there is one slightly nit-picky error (nit-picky on my part…hahah) regarding FM radios.

    He said “The FM band frequencies were changed after World War II, so if you have a radio that tunes FM from 42-50 megahertz rather than the modern 88-108 megahertz band, you know it was manufactured before 1942.”

    While that is true in most cases, there is at lease one exception. I have a Zenith model 8H034 that has both the old and the new FM band and it was manufactured in 1946.

    You might want to point out someplace that from 1942-1945 most US radio production was restricted to military applications. I have one of those interim radios made by Philco. It is a 1942 model A-361 console and it really represents the war years. Car manufactures had switched to manufacture of military vehicles and likewise radio manufactures had switched to military radios. So here was Philco with a bunch of CAR radios in inventory and no cars to put them in. So they came up with this A-361 model that used a CAR RADIO in place of the conventional console radio. You can see mine on this page:

    http://www.antiqueradiomuseum.org/consoleradios.htm

    Thanks
    Jim Tripp / http://www.AntiqueRadioMuseum.org

  2. KAIVAN J DARUKHANAWALLA Says:

    i have visited your site and found it very informative,I would like to inform you that i have a 1937 Philco Radio with original cabinet,& a complete set of valves. I would like to put it up for sale. kindly help.

  3. Michael McLean Says:

    Hi,
    I have not been successful finding someone in the Seattle area that fixes tube radios. Do you have any resource I might check out? I have some radio tubes that appear to be new I would give them rather than toss in the garbage. I found them in an old house that was slated for demolition.
    Thank you for any assistance.

    Michael McLean

  4. charles barton Says:

    Recently i was givin my grandmas wards airline radio Floor model Article# 62-2505 117volt 50 to 60 cycles 80 watt WG&C series 10a72-655 it is in excelent shape speaker condition,all labels intact, cabinet and cloth all knobs totally functional and plays excellent.Cabinet stamped Wg 2505. I have 8 antigue books on radios but cannot find any info on this model i want to keep it in the family and wish i could get info on this model.Granny said granpa bought it in the 30s new for a present for her.

  5. david Says:

    If the newly acquired radio has only five or six tubes and no transformer, except on the speaker, do not, repaet DO NOT plug it into the wall without an isolation transformer. These radios had a “hot” chassis, and could transmit a fatal electrical shock to the unwary user.

  6. Charlie B. Says:

    I just acquired a Philco radio D 655 124. It is in a wooden case that open like a travel case with a mirror. What was the purpose of this style. Was it as a radio and make up case. I appreciate a source that can respond to my curiousity. I have researched for a couple of hours and I can’t find out anything. Thank you

  7. Jai Vanarez Says:

    Nice site. Great article on how to create a bio of and antique radio.

    I hope you do not mind me asking a question. I want to find an RCA radio circa 1930s. My grandmother had one and it was lost. I do not have the exact model number. Only remember that it was like T and a 7. It looked like this: It had a bakelight. Three dial butoms below the dial. The Station indicator was positioned in the middle of the dial and it rotated all around the dial. The dial was positioned on the right, and the speaker, covered with cloth, was on the left. The casing was dark brown, part plastic and part wood. It had short wave capability.

    Any help is greatly appreciated.

    Regards,

    Jai Vanarez
    Florida

  8. Jerry Millner Says:

    I just picked up a Atwater Kent 655 floor model radio. It was my grandparents
    and I would like to restore it. Need leads for parts and stain colors.
    THANKS for any help you can send my way. Thanks Jerry

  9. Mary Mills Says:

    I just purchased a wood table radio phonograph that has the following number in the back T83116 and 10535-A and 761224 Patent 39-6694. Can you give me any idea of the age. Many thanks!

  10. Dwane McFerrin Says:

    I have inherited an Atwater Kent Model 70 radio. The cabinet needs to be refinished. I’m in the Omaha, NE area. Please advise on a local source for reviewing the radio which appears to be in good shape. I haven’t plugged it in and based on your article won’t until someone qualified has had an opportunity to look things over. Any suggestions on an expert in the Nebraska/Iowa area would be appreciated.

  11. Kenneth Key Says:

    Thanks for the great information!

    I have just purchased a RCA Victor radio at a yard sale for $3.00. I am having some problems finding information for this model (8X53). The label is in good condition and easy to read. There is NO plans to plugs it in at this time, but I was just wondering what it is worth and the year. Can you help me?

    Thanks

  12. Patrick Wesley Says:

    I recently inherited a Grundig KONZERTSCHRANK 9088 made in either 1957 or 1958, it is in fairly nice condition, minus the speakers I removed about 30 years ago, hindsight would have nice at the time. Becuase of my error, I am now in search of original speakers, manuals, etc… I am also curious of its value. Can anyone help me?

    Thanks

  13. Gale L. Says:

    Well, I wish I had read this article before I fired up an old Marconi 183A I found in the basement. Sure enough, a spark and an explosion and then a strong odour, as in electrical fire. I immediately turned the radio off and unplugged it. I suppose I wrecked it, eh?

  14. Deloy Fox Says:

    I have two console radios. A Philco Model 118 and a Firestone 3148A. Trying to find out the value of each and if any parts are still available.

    Can anyone help?

  15. Jack Boerstler Says:

    I bought a Emerson radio (model 558) as a youth by saving my money and then loaned it to a friend who took it on his vacation and broke the case. Of course I was was heart broken, but kept the radio and just recently came across it in the attic. Questions: Is there any chance that the cabinet can be replaced? and is the “B” battery still available? I am sure that the radio can work as it has not played much. I under stand that the capactors do dry out over years but I am hoping that that they will be ok.

  16. Wes Says:

    I have an Atwater Kent Model 72 (says so on back). Problem is, I have never found any reference to that particular model. Model 70 pictures I have seen look exactly like it, but mine states that it is a Model 72 ??? I would like info on year (1930?), potential value, etc. Thanks in advance!

  17. Tony Says:

    Dear Sir,
    I am in the possession of what I consider a rear Radio. In fact when you push a button at the back a turntable is revealed. I have not been able to identify a makers name but the serial number is 13777= Model No 1508 A small his magesty Voice is stuck on the top Plus a licence plate> Marconi Valves are also noted on it. Is it possible that you can help me with information regarding this radio. I find youre site very interesting.
    I look forward to hearing from you Tony

  18. Toi Says:

    Just acquired an Olympic Model 780 with leather case, and Spica transistor 6model st 600..was wondering what their worth was and where can i send them for conditioning….

    thanks

  19. Andy Says:

    I’m trying to find out how much a Zenith 8H034 radio is worth. It’s in decent shape and does turn on. I was able to hear at least one station until the tuner “cord” broke.

    Thanks,

    Andy

  20. kenneth Says:

    I have an old Cathedral style Philco radio Cord is frial and has a weak tube is there parts availible to replace tube and power cord. also is there antenia that goes to radio

  21. Nancy Barwick Says:

    I have an RCA Victor turn table – Model 7-EY-1DJ and am looking for someone in the Omaha, Ne area to get it working again. I need a needle too.

    Thank you in advance for your help.

    Kind regards
    Nancy Barwick

  22. Bill Stone Says:

    I have a RCA Victor Model BP-10 portable radio. It has tubes inside of it yet it runs soely off of batteries. One of the batteries is a “B” battery and the other is an “A”. I have never seen a portable radio with tubes inside and I cannot find anything on its age. Do you have any info on this radio. It is in excellent condition. I do not know if it works as I have yet to find a “B” battery to replace the old one.

  23. James Williams Says:

    I have an RCA Victor Serial#039882. It still works and plays. Everything on it is original as it was when bought. What I would like to know is if you couold tell me the date it was made? Is there a way to trace the serial number and find out how old it is?
    Hope to hear from you soon.

  24. Joyce Roberts Says:

    How can I find out about an antque Zenith Console Model # A134923

  25. albert m brodeur Says:

    I am looking for a schematic/parts list for a Emerson mod 578A

  26. Bryon Trewin Says:

    I’ve got a Philco radio 1938 from pics I’ve seen. The paper label has been painted over. Can I still identify which model this is? How?

  27. alec pollock Says:

    i have a montgomery ward airline radio “ugly duckling” near as i can figure it was built in 1938 trying to find out what its worth cabinet is real nice and original few spots of paint on it

  28. mark Says:

    hi there just wondering if anyone could tell me about a portable radio we have its a k432 stromberg carlson the only one that i have found on the net is in the power house museum in sydney

  29. hank koontz Says:

    i have a philco console radio in excellent condition and all works. it is a model41-610 player,recorder – cuts its own record with original speaker to talk in. it also has overseas band, needle cleaner, home recorder unit model hr-1,flip open top to controls, push buttons to your favorite radio stations, original owners manuels. i would like info and worth for insurance purposes. thanks

  30. gary leblanc Says:

    picked up a sweat (polle royal radio) this weekend ……really nice shape and i would like to know what type of speaker they would of used with it ,and antenner ,i know it was set up for batterys ,but you can run a battery eliminator what brand i have no idear…an idear on price of the radio would be nice but i know its hard with out seeing.but a ballpark price would be nice .as well as how rare…
    thanks
    Gary

  31. Sarah Lowrey Says:

    A correction on your brief statement on transistor radios: The transistor was invented in 1947, but the first transistor radios were introduced in the Fall of 1954. It is quite incorrect to state that any transistor radio was made after 1957–by that time, there were several models made by both American and Japanese manufacturers.

  32. Dave Jacobson Says:

    I am interested in the Zenith Royal 750 and the different colors that the leather case came in. I have read that it comes in black and tan but I recently acquired a blue one. Does anyone know which colors are more or less common?

  33. DAVID THOMPSON Says:

    I need a schematic for a Zenith radio (Model 8GOO5TZ1Y). Any help greatly appreciated. I have started replacing the capacitors.

  34. Ed Sottile Says:

    I have a 1929 -642 Stromberg Carlson. The cabinet is in perfect shape but no guts. Is it passable to get all new for the inside ? If so ware do i go or contact. Thank you.


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