[R-390] "Fake" 12AX7 tubes on e*pay

[Drew Papanek]

Tim Shoppa wrote:

>I have many "Tesla"/"JJ" (E European) 12AU7A's (actually labeled ECC82,
>I always thought ECC82 equals 12AU7A's but seeing the subject line maybe 
>you
>don't think so) and several have already failed with cathode-to-heater 
>shorts in the past couple years. Maybe 30% failure rate. That is not
>"excellent" in my book, to me it indicates less-than-stellar manufacturing.

<snipped>

In Tesla/JJ's defense, the factory was destroyed by  bombing missions during 
the US
campaign there (Serbia).  I think it would be difficult to maintain quality 
control with bombs
detonating all around you, the ceilings and walls collapsing and your 
co-workers dying.

Perhaps the tubes to which Tim refers are from a lot made around that time.

On Sovtek tubes, I have a Hallicrafters HT-9 transmitter which uses six 
6L6's in various roles.
The crystal oscillator stage uses a 6L6 and runs about 430 volts on the 
plate.  I tried a Sovtek 6L6GC,
American 6L6GB, 6L6GAY, metal original 6L6 and all gave identical ample grid 
drive to the next stage.

That oscillator stage pushes crystals quite hard-makes FT-243 types drift 
like crazy from heating, fractures HC-6/U types in seconds.

Yeah, I prefer the old American tubes, but will take what I can get to keep 
the radios running.   Besides, any organization that still makes tubes in 
this day and age can't be all bad, can they?

Drew