[Milsurplus] 304TLs...

[Kenneth G. Gordon]

On 12 Dec 2017 at 13:08, KD7JYK DM09 wrote:

> Thanks.  I have a dozen and a half, maybe two dozen, NOS, about half 
> commercial, half military.  Got a lot from McDonnell Douglas with a 
> carbon dating machine, they were used to heat samples at 27.12 MHz, got 
> several more by trading two small parabolic antennas.  I have a handful 
> of sockets somewhere as well.  Guess I won't be paying off my mortgage 
> with them...

I plan to use mine to build single-band amplifiers. Two in push-pull, biased in Class B. First 
for 160 meters.

Once, back in the 1960s, I got about a dozen of them from a local Chemistry department. 
They had been used as shunt-regulators in a big NMR machine. They were so flat they 
wouldn't pull any current even at full 2KV plate voltage and no grid bias.

I "reactivated" them and they worked like new for many years afterwards. I gave them to 
friends. We used them in our BC-610 "linear" amps too.

The filaments in those things are HUGE and have tons of "reserve".

About the only way you can destroy one is with a hammer. They are about as tough a tube 
as I have ever used. Far tougher than a 3-500Z for instance.

Too bad their IMD performance is sub-par today.

Also, they exhibit a very bad tendancy to suddenly oscillate at ~40 MHz in most circuits. 

Installing a trap tuned to ~40 MHz in the grid lead stops THAT foolishness.

Ken W7EKB

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