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Re: GL-434A tube (specs wanted!)
Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-uswest-dot-net>" <evp-at-pacbell-dot-net>
Tesla list wrote:
> Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>"
> Hi Ed,
> All very good points. I have sockets for them, which should facilitate
> connections somewhat. I think they will be prone to VHF oscillations,
> which may be prevented with the resistor / coil impedance that is
> frequently stuck in line with the plate leads in broadcast amps. Not quite
> sure what to do with grid no. 2 yet...for plasma tweeters, modulation can
> be introduced here, and perhaps it's a way to throttle the coil's power.
> Some people have just wired both grids together, with the disadvantage that
> the tube curves and normal operating parameters are not available. Plate
> voltage is listed at 2 kV in my handbook...and to me this means they will
> probably manage 3 kV with care. I am going to try them in a push-pull
> circuit, which I hope to use to drive a "half wave" type of coil. I'll let
> y'all know what happens...
Fine. As for the grids, you have the choices of using the tube as a
tetrode the way god made it, tying the grids together for a high-mu
triode, or tying the screen to the plate for a lower mu. In order to do
the latter you need to find out if the tube is rated for that service,
as the screen might get too hot. Don't have that data, but suspect you
could find it digging around on the web. As an alternative, I suspect a
call to Eimac might help too. (I just looked at the 4CX250 data sheet
at the Eimac site, and they rate the screen voltage as around 300 volts
in typical service. They also state the maximum screen dissipation as
12 watts, so think you don't want to tie it to the plate.