[Hallicrafters] HT-44 Carrier balance drift

[Jeff]

Input appreciated:

Have a working HT-44 that's getting excellent audio reports and good 
spectrum views on air.  I've aligned the audio phasing for a good circle 
pattern at 1 KHz.

In going through it, I found the 22K 2 watt resistors feeding the 
balanced modulators to have different values.  I replaced both with 
metal oxide resistors.  Voltages on the plates are 80 volts (manual says 
60, but also feeding it at 123 VAC.)  After a day or two, I checked them 
and they have been clearly subjected to heat -- paint is now hard to 
tell what color it was. When I removed the original carbon comps, one of 
them was also quite toasted looking.  There's no evidence of any other 
component stress however.  The 12BH7s are closely matched and test good.

Second, and maybe related, I am having difficulty maintaining carrier 
suppression.  At first turn on, the carrier shows quite high- maybe 5-10 
watts out at full power (130 watts).  removing the cover and adjusting 
the balance pots will quickly take it back to zero, but as the rig 
heats, it goes off again.  Eventually, it stops "drifting" and I'm able 
to set it so it stays suppressed.

The 22K resistors appear to drop the full B+ to the stated voltages, so 
I would expect for them to get warm. It bothers me to see them thermally 
stressed like that though.  I suppose I could put in a couple of 5 watt 
resistors, but that seems like it might just be masking a problem.

As I said, the rig is getting excellent reports.  I have it slaved to a 
SX-117 and am successfully using it in transceive configuration, so I 
don't want to overly tinker with something that's more or less working.  
It's just that the carrier balance controls are inconvenient to have to 
tweak.

If anybody out there has experience with this rig, let me know. Perhaps 
it's just the nature of the beast?  I do know that my other phasing rigs 
will hold carrier balance well enough, so I'd be disappointed to hear 
that this one wont.

Jeff
WB3JIH