[Collins] Low Grid Drive - KWM-2

[Dr.Gerald Johnson]

Last time this came up, it proved to be a weak RF driver tube. It could be lots of 
things though including a weak crystal oscillator tube (that doubles in the plate 
for 20, 15, and 10 meters), or weak tubes from the last mixer to the RF driver 
tubes. Could be a band switch contact problem, a coil shield problem, a RF 
driver or PA neutralization problem (including the RF feedback), could be several 
bad trimmers in the RF section not necessarily the same stage for each band, 
could be a broken PA neutralization capacitor. Check the tubes first. When you 
do replace the RF driver tube be sure to neutralize it.

I can be anything in the linear transmit chain that is band switched from crystal 
oscillator on. Or a combination of things. Check the tubes first.

73, Jerry, K0CQ, Technical Advisor to the CRA

-- 
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.