[Moon-net] Gain of a tetrode (TH347)

[Koellner, Guenter (NSN - DE/Germany - MiniMD)]

Hello,
 
back to a technical question:
 
On 23cm, my amp is using a TH347. I have about 75W drive (from a GSM amplifier) and am getting about 950W output from it. While tuning and optimizing, I found that the gain increases when I am increasing the idle current, so this situation is at 300mA drive power.
 
I am now going to get more drive power, the plate current might become too high and the plate loss too much. In order to compensate here, I may reduce the idle current. But, how much less gain may I get when I for example reduce idle to 50mA. Not that I now drive it with 3dB more and on the other hand loose 3dB of gain, so that at the end the output is equal.
 
73, Günter (dl4mea)