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Re: Vacuum Tube Database; looking for 811A coil design
Original poster: davetracer@xxxxxxx
Thank you for this extremely useful tube database!
I've built several vacuum-tube Tesla Coils and found that their
output was so tightly controlled that I easily could draw the
discharge to anything metallic in my hand. (The metal was needed just
to avoid RF burns). After that I started building with Neon Sign
Transformers and the frequencies all over the place, if you'll pardon
the expression, came as a rude shock. But wow, do I wish I'd had an
oscilliscope while trying to tune my early tube efforts!!
I no longer have the VTTC schematic, but perhaps someone could
point me to one? It used two 811A triodes in parallel, and a Stancor
1200V transformer for plate voltage, as well as the 6.3 volt
filaments. The primary was 20 turns, and there was a second 20 turn
coil feeding back to the grid with capacitor to tune it. If I recall
right, those were wound on a Quaker Oatmeal box : - ) .
Another surprise was finding out that the only people making
811A's any more were the Soviet Union, and if I ran the tubes
anywhere near their supposed power rating, they collapsed internally.
I do have the original datasheet from GE for the 811A from the
1930's. I think the ones I have kept are labelled "SovTek" but am not
sure; SovTek makes a lot of tubes for the musician market, so I think
their focus more on 6L6's for things like Fender Super Twin
amplifiers. My guess is they made these tubes to help EMP-proof their fighters.
Also, I have no idea where to find things like plate connectors,
four-pin sockets, and the like since Dave Fistell passed away. He was
a good friend, and unlike the people running his place now, enjoyed
helping a young kid find out about Tesla.
So .. anyone know where to find said tubes, plate connectors,
sockets, and VTTC schematics these days? Are 811A's even a good tube
to work with? I've seen other tubes discussed here..
-- many thanks,
Real useful for the "hollow state" enthusiasts and VTTC crowd...
Dave Sharpe, TCBOR/HEAS