[Amps] 3cx800a7 Grid Current Problem

[George Steube]

Carl/Paul,
There isn't a fix loading padder (Carl, I think you are referring to a 
capacitor pad for 160M correct me if I am wrong) in the HF 1250.  There 
is a tapped ferrite transformer/coil that is switched in for 40-80-160.  
That being the case the problem could be something shorting out part of 
that transformer in the 160M position.  Also the band switch could be 
bad.  Have you checked all the components in the RF compartment for 
visual damage/overheating/value?  The only difference in the 
tuning/loading circuit between 80M and 160M is the position of the band 
switch and which part of the above coil is in the circuit.

Another point to consider is that the LP100A has three different 
selections for measuring output power(average/peak/?pulse?).  I find 
that if you are tuning a twitchy amplifier a needle type watt meter is 
easier to use than the LP100 (maybe it's just me).  I think if you are 
not using a pecker tuner,  peak is recommended, check the manual.  Also 
carefully follow the instructions in the HF 1250 manual as to the way 
you tune the amp.  I found those instructions will prevent surprise grid 
current fluctuations.  Good luck.

73
George
W2GS