Identifying Vintage NOS Vacuum Tubes by Brand Country and EIA Code
David Mell, Copyright 2016
The topic of who really produced a tube and where causes a huge amount of confusion in the community. The vacuum tube business was a very incestuous one, so much so that you can rarely trust everything that is printed on a tube. Sometimes even the best tube dealers get stumped and you’ll see all kinds of incorrect listings on the web. Often, the printed brand or printed country is incorrect.
Vacuum tubes were simply a commodity that everyone needed like batteries or light bulbs are today. For the most part, back then no one cared when a tube was made or who made it, they just wanted a good product that would work and bring their radio, amplifier or TV back to life. Which is part of the reason it can be so hard to figure out today.
There were a few different reasons a given company would re-brand or write the wrong country of origin on a tube.
They ran out of stock of one particular type and contracted another company to make them to fulfill an order. This is why you see even major brands like Sylvania with RCA date codes.If they could source the tubes cheaper than they could manufacture them. Ironically, European tubes like Telefunken and Mullard were seen as inferior to US tubes at the time as they were cheaper and many tubes you will see an RCA labeled tube that was really produced by Telefunken.
- The company simply didn’t have the equipment to produce a particular type of tube but demand was high. A good example is Loctal tubes. Only Sylvania and National Union had the equipment to make them. Despite what a tube has printed, they were made by one of the two companies only. You’ll find Loctal tubes branded everything from RCA to Westinghouse.
- They had a contract with a large company to print their logos on the tubes. It was in the interest of companies like DuMont, Admiral, Emerson etc to have their own logos on the tubes that they supplied in their equipment. They did this in hopes that when a tube failed the customer would order a tube with the same brand as their equipment at a markup so the company would profit.
- The manufacturer sold in bulk to a wholesaler or distributor that marketed the tubes differently for a profit. There are many brands out there that never manufactured their own tubes. To make things worse, these companies usually removed any clues as to who made the tube like EIA codes. This is actually more common today with New Production tubes. Some common vintage re-branders are IEC, United, Ultron, Arcturus (post 1950s), International Service Master and moreIn the cases where the country of origin is incorrect, it usually had to do middle man companies in Europe trying to get around regulations. We often will see tubes marked “Made in Germany” that were really made in Russia. There were many trade sanctions due to the various wars that went on while tubes were still being produced in bulk.
When trying to identify a tube it makes the most sense to first determine where it was made. This is important for two reasons. Depending on where it was made, you there are different clues to look for. Once you know where it was made, that narrows down the possible manufacturers by a lot.
Codes
The first place to start is to look for EIA or Manufacturer codes. When in doubt, these code should be given the most weight in your determination. There is much more to say about EIA and date codes which we have reserved for another article.
Remember, it’s common to find BOTH USA and European EIA codes on a tube. If you find the tube in North America, assume the European code is correct. If you find the tube in Europe, assume the USA code is correct.
USA codes will always be in the form of 3 or 4 numerical digits. If your tube has these codes on it, you can get they’re USA tubes. Here are some examples and a list of common USA EIA codes.
3 Digit 280 Code = Raytheon, Made in USA 3 Digit 188 Code = GE, Made in USA
Common USA EIA Codes
|
Amperex (USA) |
111 |
|
Bendix |
125 |
|
DuMont |
158 |
|
Eimac (Eitel-McCullough, Inc) |
162 |
|
Electronic Tube Corp |
169 |
|
General Electric Co (USA) |
188 |
|
Hytron (CBS-Hytron) |
210 |
|
Machlett |
231 |
|
RCA (Radio Corp of America) |
274 |
|
Raytheon |
280 |
|
Superior Tube Co |
310 |
|
Sylvania (Hygrade Sylvania Corp) |
312 |
|
Tung-Sol |
322 |
|
United Electronics |
323 |
|
Western Electric |
336 |
|
Westinghouse |
337 |
|
Zenith Radio Corp (CRT's) |
343 |
|
Nortn American Philips Corp |
423 |
|
Taylor (aka Cetron-Taylor) |
713 |
|
Lewis & Kaufman |
738 |
|
National Electronics (also Cetron) |
749 |
|
Penta Laboratories |
771 |
|
Vacuum Tube Products |
781 |
|
Varian Associates |
809 |
|
Litton Industries |
879 |
|
Electrons, Inc |
935 |
European Codes
European codes can be a bit more difficult to decipher. Typically, European codes are printed a chalky, easily rubbed off type of paint towards the bottom of the tube near the pins. Once you've seen this type of paint it's easy to spot. While the codes are usually at the bottom, we have seen these codes in other places like the bottom of the base.
Euro codes usually have two lines, the first consisting of 3 or 4 digits and the second almost always having just three digits. Unusually there is a series of letters, numbers and symbols mixed together. Much can be deciphered from these codes but that's for another article. All we are concerned with here is the Manufacturer code. The Manufacturer code is always the first symbol on the second line.
An example of a rare Mullard 12AX7 code is:
Mc1
b1k2
Since "b" is the code for Mullard, made in Blackburn England, you know the tube was made by Mullard
Another Example of a Mazda code:
I65
L2k2
"L" is the code for Mazda in Belgium
Above we see the R as the first digit of the second line which points to Mullard made in Great Britain even though this tube has Amperex as a printed brand.
Here is a list of European factory codes courtasy of audiotubes.com
Printed Country of Origin
Not all tubes will have an EIA or Manufacturer’s code. In that case, the next best thing is to identify where the tubes was made.
Many tubes have a printed country of origin on them. In many cases this is incorrect. If a tube has an etched "USA" and NO other countries printed on it and USA EIA codes, chances are you do have a USA made tube. If a tube has both USA and another country printed on it, you have to do some further investigation. As noted before, European tube print was made with a chalky substance and is easily identifiable and rubbed off. If your tube has a country printed in this ink, you can trust what the ink says which helps identify who made it. If the tube has no codes but says "Germany" there are only a handful of manufacturers it could be.
Exceptions & Other Clues
Many but not all European tubes will briefly flash a bright white light when they are switched on.
Russian UFO Getters
For some reason, it's quite common to find Soviet era Russian tubes marked made in Germany, England, Holland etc. Russian tubes tend to have distinct mica spacers and are slightly skinnier than US tubes but the biggest giveaway is the getter. Almost all vintage Russian tubes have what is called a UFO or Flying Saucer getter. If you see this type of getter, there is no doubt it's a less valuable Russian tube even if it's a Telefunken labeled West Germany.
UFO Getter - Always Russian
Most small Telefunken tubes have a diamond engraved on the bottom of the tube
The Stop-Sign Misconception
Many sources claim that RCA was the only company to use the classic Stop-Sign around the tube type. This is not true, many companies used it. We have seen Tung-Sol and Sylvania with the Stop Sign logo.
GE Dots
GE used an etched dot system to mark their tubes. If you see these dots, you know you have a GE tube.
