[Heathkit] The HW-16: Is that my final answer?

[Tom NØJMY - AAR7FV]

In the saga of  my continuing quest to understand what makes HW-16's hum 
at idle, the problem turned out to be...Lord only knows.  I substituted 
another 6HF8, tried all the suggestions from everyone on these lists, 
even checked for heater-cathode leakage in the final (found a note that 
N2EY wrote where that can be a problem.)  I also RE-recapped the P.S. 
with radial-lead caps (2-100 uf, 4-82 uf, and a couple 47 uf on the bias 
supply) to get the leads down to a bare minimum.  Plus, I loosened, then 
tightened every screw and nut, re-heated every solder joint I could 
reach, and corrected the out-of-spec bias voltages.  Hummmmmmm.  Just 
like 90% of the HW-16's I've had.  Maybe I'm being overly picky with 
this cochlear implant!  Again, this is the phenomena where the hum is 
audible only with the AF gain at minimum, then it drops off and 
disappears at about half-throttle.

So, I utilized the fix I had settled on originally and bypassed the 
audio power-amp grid with .01 uf cap.  Now she's as quiet as can be. 
Plenty of gain, though.

The best part is, I had her on 80 and 40 tonight with my inverted-vee, 
and worked Ohio, Arizona and Oregon, receiving a clean bill of health as 
far as chirp, click, or yoops from each one in turn.  I specifically 
questioned each one on these subjects.  Of course, it's not official 
until I work a couple of you guys that I know will be brutally honest 
with me hi HI.

BTW, I was rock bound and did not use the Pierce oscillator capacitor 
mod.  I guess even a blind hog finds an acorn, now and then.

I'll check it out on 15 tomorrow, then I'll see if I can work some of 
you guys over the weekend.  Every has to be ship-shape when I ship it 
out to Jerry, N5KYE, on Monday.  BTW, many thanks to Jim, W5JO, for 
sending Jerry to me.

Glad to see NR5A is going to recap his.  That should make all the 
difference. I'm keeping my fingers crossed.

73,
Tom