|[AMRadio] Pi-Net vs Link Couple|
w5jo at brightok.net
Fri Sep 23 09:55:31 EDT 2005
W7QHO at aol.com wrote:
> In a message dated 9/22/05 7:30:13 PM, w5omr at satx.rr.com writes:
>>that's interesting, Darrell... a reactor in the screen supply. Are you
>>capacitivly coupling it, as well? No, that can't be - the screens need
>>to be DC voltage. However, the choke effectivly kills any stray
> A choke in series with the screen supply exhibits a high impedance at audio
> frequencies and allows the screen to self modulate. The technique has been
> around for a long time. A screen dropping resistor of sufficient size will
> provide the same effect. The military T-368 does this with an 80K screen
> dropping resistor off the 2500 volt HV supply and applies modulation to the plate of
> 4-400 PA only. The same technique was applied in the T-195 (4X150D PA, 1KV
> plate supply).
> Dennis D. W7QHO
> Glendale, CA
This same thing (choke) is used in the Globe King series of
radios by WRL The resistor scheme is in the DX 100, etc.
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