[Boatanchors] JAN numbers

[Flowertime01 at wmconnect.com]

In a message dated 3/29/05 6:06:45 PM Eastern Standard Time, 
w5jo at brightok.net writes:

73  
Jim W5JO

The military, at one time, used a VT number to identify tubes.  

Yes and so did very one else. Life was to easy so something had to be done.

That was changed to a JAN number.

Well, some tubes were changed to Joint Army Navy. If the Army or the Navy 
happened to be using the tube.

Today (last 40 years) have found tubes with the Alpha Numeric (6BA6, 6C4) and 
industrial tube numbers (5814, 6821, 6082). 

Some industrial tubes have older Alpha Numeric and industrial part numbers 
(6AK5, 5654) If it was built to industrial strength and the commercial tube 
values.

Unless you are operating in an ugly (military) environment you do not need to 
worry if your part is JAN or not.

Mostly JAN is to put the tube in a standard military parts package (box)
JAN tubes were tested (in test frames of a 100 plus tubes at a time). Good 
middle range tubes were inked with JAN marking and packed for military use. Real 
hot tubes were marked as commercial parts and packed in Brand boxes. (Tubes 
that test real hot in a tube tester are likely more noisy than not so hot 
tubes.) The poor ones were boxed in odd brand boxes. Some failed and hit the trash.

However in the IF deck of a R390/A it has been found the 5749 has a better 
signal to noise performance than commercial 6BA6 / 5729 or European EF95.

In most places any of the 4 tube types will work. There is differences in 
noise and gain from manufacture and production run to production run. Most days 
any tube that passes on the tube tester will be OK. But picking and choosing 
tubes in an R390/A receiver can get you from an OK 10 UV sensitive and 10 :1 
signal to noise down to 2 UV sensitive and as high as 30: 1 signal to noise. You 
need some real knowledge of the receiver going in and lots of different tubes 
to select from.
> 
> 
> Maybe someone here can give me some information. 
> 
> My question is, did they use the OEM number and simply add the letters "JAN" 
> to the tube number,
> 
> Yes.


> cross over number to an 
> OEM number.

OEM numbers do not really exist in tubes. A factory makes tubes. The factory 
may be owned by a large entity with a name recognized for some Brand or 
Product.

GE, RCA, Raytheon, Sylvania actually once upon a time operated vacuum tube 
manufacturing factories.

These factories would make any tube and put any Brand on it you wanted.
A lot of JAN was to have two sources or more of manufacture. Many factories 
made the required JAN tubes in limited quantities to meet contract compliance.

Some Brands would make a tube and other Brands would not. Many tubes are 
identical in function and have a different base configuration. The pin out would 
be swapped around. Designers would speck a chassis with all the RCA or Sylvania 
Tubes. Raytheon would make any thing and every thing. They did a lot of JAN 
tubes to keep production up. Raytheon had some special VHF tubes and 
transmitter tubes. But a weeks production would meet the worlds demand for a year or 
more. So the factory would make any thing for any body to keep the factory in 
production. As long as they were doing Military qualification for there Radar 
Tubes, Hey lets get the most return and run what ever makes the most income.

So you find JAN 6C4 and 6C4 with Brands A 12AU7 is a dual 6C4 A 6SN7 is a 
dual 6C4 in an 8 pin octal socket. Same set of tube values for the triode. Very 
different packages. None of these would be considered OEM part numbers.


Just for entertainment value, Europe has an entire set of there own tubes. 
Many are identical to American tubes. Some are unique. The Russians have a set 
of there own tubes as well as the Chinese. Some are equal and interchangeable 
with American tubes some are not. 

The Russians trying to keep what production they have alive are making 
American tubes for the US consumer market. They have taken on some high end Audio 
tubes. When they started the stuff was so so. Today some of the product is very 
good.

Roger L. Ruszkowski KC6TRU