[Heathkit] Coil shielding cover clips and PA parasitic suppressors

[Ted Bruce]

Hi Dick,
I must have missed the bulletin regarding the coil cover clips. Considering the numerous grounding problems reported with the circuit boards, I'm not sure it's a good idea to ignore them, even though I guess this is a shielding issue primarily. In order to get my HW-101 stabilized, I followed some advice and installed braid (solder wick) to the outer rim ground traces to screw tabs that I installed under the nuts holding all of the PC boards in the rig down to the chassis. I did this in a few places on each board.

The person who recommended this to me said that it cured instabilities in his rig, including the inability to neutralize the finals. The technique was also corroborated by Allison, KB1GMX who similarly did similar improvement to the grounding for her rig.

As to the removal of the parasitic suppressors, I assume that you mean the coils around the 2 watt composition resistors at the PA plate caps. That doesn't sound like a good idea. Some more modern rigs, including several linear amplifier designs, don't use the wrapped resistor approach; they instead mount the coil and resistor in parallel side by side for each tube. I suppose a few people will weigh in on the advisability of removing these suppressors.

73, 
Ted, KX4OM