[Amps] Command Technologies HF-1250 Intermittent

[Paul Elliott]

This amp, which has factory installed QSK, works fine sometimes, but other
times it doesn't.  I do not use QSK; I switch between transmit and receive
manually.  When transmitting on CW, the output power (as measured by a
LP-100A) will suddenly drop to drive power.  In other words, the amp goes
into the bypass mode for RF-but the plate current meter is showing the 70 or
80 ma zero signal standby current.  Sometimes, when sending a string of
dots, the amp will, randomly, go back and forth between full output (700
watts or so) and drive power output (30 watts or so).

 

As best as I can tell from the partial schematic that I have, it appears
that relay K2 is opening and closing.  Relay problem?  QSK circuit problem?


 

I am not physically able to manhandle this amp, certainly not to the extent
to take it apart to get to the circuits that should have had an access panel
on the bottom of the case.  If I could relatively easily, somehow,
completely take the QSK circuit out of the picture, I would try that.

 

Today this beautifully clean amp is working fine-but I expect a return trip
from Murphy.

 

Any help appreciated.

 

73 Paul W5DM