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

[Greg Mijal]

S meter drift may sometimes be eliminated by doubling or tripling the
wattage of the resistors involved in the actual meter read out circuit. A
good way to check is to run up the radio and watch for drift.  Cool down the
resistors with circuit cooler or ice in a bag. If the drift stops go ahead
and refit the resistors with higher wattage ones.
Good luck
Greg

----- Original Message ----- 
From: "Ken Kaplan" <krkaplan at cox.net>
To: "Edward B Richards" <zuu6k at juno.com>; <heathkit at mailman.qth.net>
Sent: Wednesday, February 22, 2006 9:41 AM
Subject: [Heathkit] Re: Restoring HW-101: S-meter + tone in audio questions


> 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
>
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