[Heath] SB-200 loading question.

[Glen Zook]

With my SB-200, I have found that increasing the loading slightly after achieving maximum output results in only a very small percentage of power reduction but reduces the grid current substantially.  Depending on the band, I can get 600-watts out with less than 25 mA total grid current.
 Glen, K9STH 
Website: http://k9sth.net

      From: Kenneth G. Gordon <kgordon2006 at frontier.com>

Sigh....no, as Kevin mentioned, I was thinking "backwards".

I had forgotten that LESS capacitance at the loading control equals MORE output to the 
antenna.

There is nothing wrong with the amp: it is simply operator error.

I watch grid current very closely and keep it less than 50 mA per tube. Usually I try to keep it 
about 35 mA per tube, in fact. 

I have always regarded grid current as the most critical parameter one should track in GG 
amps. That is one reason I have always thought the FL-2100 was weird: there is no way to 
monitor grid current with that amp in its stock configuration.

I have also modified the input circuitry to my SB-200 so that it shows no more than 1.5:1 
over those portions that I use in all ham bands.

Power output on 80 meters with new RF Parts 572Bs is 600 watts with about 50 watts of 
drive power. Plate current is less than 500 mA. All this makes me happy, and the amp 
seems to be happy too.

My thanks to Kevin for waking me up.

Ken W7EKB

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