[Heathkit] HW-16 hum

[Rbethman]

Ken,

I had similar problems with a HW-12.  Turned there was some grid to grid 
issue in the final.

You may want to go look there.  Mine worked just fine EXCEPT for that 
dreaded 60 cycle hum.

It came on all of a sudden, and replacement of the final fixed it.

Bob - N0DGN

Kenneth G. Gordon wrote:

>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
>  
>
                       Bob Bethman - NØDGN
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