>
>I agree that the components, esp tubes, have improved since the early
>designs. Capacitors are similarly lower L, and higher self-resonance.
>For instance, to bypass the filament leads coming out of a Burle 4616
>tetrode running at 200 MHz, we used to have a ring of 0.001 ceramic
>disk capacitors around each stem of the tube.
Typical 0.001uF disc ceramic capacitors resonate at c. 50MHz.
Above the resonant freq., a capacitor looks inductive.
> It was like a pair of
>garters made from a two springs, that held the caps from the hot side
>to ground side of an insulator ring. 4616 has internal mica bypass
>capacitors in the vacuum envelope for both filaments and screen grid.
>In this manner, this tetrode can run over 20 dB of power gain, at
>200-450 Mhz range. Try that with any other gridded vacuum tube. ..
Extraordinary.
... interesting discourse, John.
cheers
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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