Re: Series-Pass tubes - Class C Audio Modulation

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Original poster: "Stephen Conner by way of Terry Fritz <teslalist-at-qwest-dot-net>" <steve-at-scopeboy-dot-com>

At 17:19 02/04/03 -0700, you wrote:
>Original poster: "Mccauley, Daniel H by way of Terry Fritz 
><teslalist-at-qwest-dot-net>" <daniel.h.mccauley-at-lmco-dot-com>
>
> >>> Could you recommend some tubes which would be available to use as
>Series-Pass tubes???

You're looking for tubes that can dissipate half the power of your coil, 
and withstand the full HT voltage without flashing over. The last part is a 
tall order if you're running off 4kV. You'll probably be limited to RF 
power tubes similar to the 833As you're using already. You'll also need an 
amplifier stage to boost the audio up to the 4kV p-p needed for full 
modulation (the series pass tube is a cathode follower with gain of ~1) A 
TV sweep tube like the EL509 (run off 2kV with a choke plate load) might do 
the job here. My tube experience is all below 750V but I'm sure there are 
some hams on the list who could help out with tube choice.

Steve C.