[Hallicrafters] Need Help With SX-101 USB Problem

[hwhall at compuserve.com]

I get the impression the problem might be related to a crystal that has become sluggish, and needs a lot of excitation to get started.
 

 Wayne
WB4OGM

 

-----Original Message-----
From: Mark K3MSB <mark.k3msb at gmail.com>
To: richard <ramnaz at peoplepc.com>
Cc: List Hallicrafters <Hallicrafters at mailman.qth.net>
Sent: Wed, Jul 15, 2015 5:33 pm
Subject: Re: [Hallicrafters] Need Help With SX-101 USB Problem


Hi Richard

I have an SX-101A and have exactly the same problem you're
experiencing.

I've had my receiver for about 15 years and it started to do
this about 5
years ago.  I swapped the USB crystal with the one in my SX-111
and the
problem went away.

It came back last winter.    USB works fine when
the radio is turned on,
but cuts out after a while.   Switching between USB and
LSB sometimes
helps;  mostly not.

I recapped my receiver several years ago
and also did the cleaning with
DeOxit.    Obviously, that didn't help.

I
think the only way to fix the problem is with an alignment as K9AXN
mentioned. 
Parts go out of tolerance after 50 years, and I'm not
surprised part of the
converter needs tweaked.     I suspect heating of a
component and the resultant
change in value is what is happening.   What
you could do it try some freeze
spray, but the offending part may be in the
converter subchassis which would
make it rather difficult to get to.

I don't know if you need an entire
alignment or not;  it's been many moons
since I cracked the manual.

73 Mark
K3MSB



On Wed, Jul 15, 2015 at 5:07 PM, richard <ramnaz at peoplepc.com>
wrote:

> Hello.
> Have a SX-101 that  when I go from USB to LSB & then want
to go back to
> USB it is Dead but if I pull the 12AT7 tube out & put it back
in then the
> receive in USB comes back on or if I turn the on & off many times
then the
> USB receive comes back on yet the LSB never goes out.. Any body have
this
> problem & if you fixed it can you tell me how? I have even put a small
fan
> inside & that does nothing .
> Thanks Much
>  Richard
>
> Richard
Morris
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