Yup - shoulda looked at the schematic first. For some reason, I was
thinking about that network in the sidetone circuit. Though the sidetone is
annoyingly high for me, it's how it was designed and I'll leave it (I use a
pitch of 440 Hz on rigs that have variable pitch). If I can even get this
to 800, I'd be okay with it. Looks like I need less capacitance than what's
in there and the value's small enough that I could use a gimmick, couldn't
I?
Off to look for some 10 pf caps or a trimmer...
Steve Wedge, W1ES/4
Live free or die: Death is not the worst of evils.
John Stark.
All my computers have my signature with various pearls of wisdom appended
thereto.
--------------------------------------------------
From: "Garey Barrell" <k4...@mindspring.com>
Sent: Thursday, April 05, 2012 10:22 PM
To: "Steve Wedge" <w1es1...@earthlink.net>
Cc: "Drake List" <drakelist@zerobeat.net>
Subject: Re: [Drakelist] Changing B-Line sidetone
Why not just replace C1 and correct the offset??
C1 needs to move the CO up about 800 Hz to put it within the passband of
the LSB, anywhere from about 800 to 2000 will work.
The frequency of the SIDETONE has nothing to do with the offset. It
should be about 800 Hz, to approximate the frequency offset in CW, but
this frequency is set by the phase shift network at V9a. This same tone
is also used for the TUNE function so must be in the range of 350 - 2400
Hz.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>
Steve Wedge wrote:
I know this has been gone over before, but my B-Twins seem to be out of
kilter: the usual assumption is the offset is 800 Hz, but my set seems to
be off by over a kHz (the offset seems to be about 1.8 kHz). I know
there are three r/c combos in the T-4X. Has anyone ever changed these
successfully?
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