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

[Edward B Richards]

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
> 
> 
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