[Heathkit] HW-16 hum

[Kenneth G. Gordon]

Hmmmm....put the scope on the HW-16s audio output line (with a 
speaker connected). My "hum" is a series of spikes spaced about every 
60 Hz.: one up and the next one down. As I turn the volume control up 
from absolute zero, the spikes get smaller, until the background noise 
starts to come up, then they get bigger again, and unsymetrical.

Looks like some sort of diode failure to me, or at least some sort of 
problem in the power supply area.

I also removed the audio output transformer, and twisted it this way and 
that with no preceptible, visual, or audible difference in hum level.

Going to replace the diodes, then see what ELSE I can find wrong.

Ken W7EKB