[Heathkit] SB-101 problem

[James M. Walker]

Those 200 ohm pots were notorious for losing wiper
contact, and I never figured if it was due to vibration
or bad product pieces that go into making the pots.

My solution was to get the cermatec blue sealed pots
that have long leads. Solder the leads in lean the pot over
and place a dab of RTV on the back of the pot and secure
it to the top of the board. NO MORE PROBLEM.

If the balance pot gets flaky, a little de-oxit will clean
the intermittent there as well.

As always YMMV
Jim
WB2FCN


----- Original Message -----
From: <k1mcn- at verizon.net>
To: <heathkit at mailman.qth.net>
Sent: Friday, April 21, 2006 9:02 AM
Subject: [Heathkit] SB-101 problem


>
>
> I have a SB-101 that I am restoring and have run into a strange problem
during the alignment I was going to adjust the idling current and found that
when I keyed the microphone the output of the rig went from 0 to full
output. I traced the problem I think to the double balanced mixer.
> It seems to have a carrier output even when there is no audio going to the
mixer. I have replaced the diodes with matched 1N191's and tested all of the
other components in the mixer. I also checked to see that the mode switch
was only grounding on side of the diode ring when in tune and CW.So far I
have had no luck in getting it not to put out a signal when there is no
audio.
>
> >From the circuit description in the manual there should be no output if
there is only the carrier oscillator is that correct?
> Has anyone run into this problem or have any ideas?
> I appreciate any help.
> Thanks,
> Matt
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