[Hammarlund] HQ-110 stability

[Kevin Ward]

I think Rodger's idea is a good one.  Also, I bet if you look at your AC 
line voltage you will see a significant change when those appliances 
kick in.  (You didn't say how soon after that load change the drift 
occurs.)  That will cause a change in filament voltage and a resultant 
change in cathode temperature and emission.  When that happens an 
oscillator will shift frequency whether the DC voltages are regulated or 
not!  This effect usually takes a few seconds to begin and continues (to 
shift) for a while afterward, until a new equilibrium is reached.

Good hunting.

Kevin  N2IE