Hi Irv,
Good to hear from ya.
Irv, there is two things you can do to that sidetone (square
wave) generator in the CII. Since I had a spare Ten Tec audio filter
from an old Triton xcvr (think it's a model 285), I just removed R90
(47k) between the center arm of the S.T. LEVEL pot and the input to U5,
the audio amp (in my schematic). I ran a wire from the resistor hole
from the pot arm to the input of the filter and from the output of the
filter, I ran a second wire to the resistor hole going to the input of
the audio amp.
I then 'jury-rigged' a mechanical means of physically mounting
the audio filter board just about the CII's IF board and I connected +12
and ground between the filter board and the IF board. (Of course you
could use any audio filter you have available to run that square wave
through to drastically improve the sidetone.) The old Triton board was
good enough because if I recall correct, it had three audio bandwidth's
to select from.
The second mod you could try, and it's a much more professional
approach, is a circuit that Steve, N4LQ came up with to replace the
entire square wave sidetone generator. It's not complicated and you can
see his schematic at:
http://www.albany.net/~bg/Mods/sidetone.htm
I also just acquired another Corsair II (think this is about my
sixth CII!!), so I'm soon going to have to make the mod again if I
decide to keep this CII. Let me know which mod you make Irv.
73,
Tom/W4BQF
Chester Alderman
calderman@cox.net
-----Original Message-----
From: tentec-bounces@contesting.com
[mailto:tentec-bounces@contesting.com] On Behalf Of Irvin Weinman
Sent: Friday, February 07, 2003 10:57 AM
To: tentec@contesting.com
Subject: Re: [TenTec] playing with the Corsair II
Tom: I am acquiring another Corsair II. I remember years ago you had
given
out the tech data to CFO types, for an audio filter mod to tame the
annoying
sidetone. Do you still have that information around? Irv W7GX.
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