[Heathkit] Re: Restoring HW-101: S-meter + tone in audio questions

[Ken Kaplan]

Regarding S-meter drift, perhaps HW-101-10 and 20 would help?

73 Ken kb7rgg

> Hi Alex;
> 
> There is a bulletin out re S-meter drift. It is caused by gassy V3 and/or
> V4. Check the grids for a + voltage. If present replace tube(s) with GE
> brand only. Most other problems can be cured by tightening all hardware.
> There was a bulletin re 40 meter low drive that moves a jumper. I don't
> recall the details. Maybe someone else does. If not, contact me and I
> will do some research. Good Luck.
> 
> 73, Ed Richards K6UUZ
> Simi Valley, Ca 93065
> Home of the Air Force 1 pavilion
> 
> On Mon, 20 Feb 2006 17:32:02 -0500 Alex <kr1st at amsat.org> writes:
> > Hi there,
> > 
> > I recently acquired a Heathkit HW-101 and I'm in the process of 
> > restoring it. So far I have replaced a handful of resistors that 
> > were 
> > out of tolerance, and also replaced some with higher power 
> > resistors. It 
> > seems to be working OK on 80 and 40 meters (RX & TX), but the higher 
> > 
> > band I select over 40 meters, the less TX power it delivers and also 
> > 
> > sensitivity is reduced. I'm not too worried about that yet.
> > 
> > To be able to zero adjust the s meter I had to apply bulletin 
> > HW-101-67 
> > which calls for the replacement of a few resistors so that one side 
> > of 
> > the s meter gets closer to ground potential. Now I can get the meter 
> > to 
> > go to zero, however, it takes about 20 minutes or so to get there 
> > after 
> > the rig is turned on. First the s meter will show over S9+60 when 
> > the 
> > rig is just turned on and then it rapidly drops to say an S5, then 
> > it 
> > takes a long time before it gets to zero. Does anyone tackled this 
> > problem before and could give me a hint?
> > 
> > I seemed to me that maybe the AVC circuit would have a problem, but 
> > 
> > things seem fine there.
> > 
> > Another problem I have is that there's a slight but annoying hum on 
> > the 
> > audio even with the AF control all the way down. It sounds kind of 
> > like 
> > an open ground or ground loop hum. I did check the grounding of all 
> > 
> > boards. When I switch the rig to CW I also hear a 1000Hz tone, again 
> > 
> > even with the AF turned down. One of the service bulletins suggests 
> > an 
> > open capacitor in the power supply, but that does not seem to be the 
> > 
> > problem. Any idea what could cause these problems?
> > 
> > 73,
> > --Alex KR1ST
> > http://www.kr1st.com