Steve -
Nope... The large section of the filter cap is additional decoupling
of the B+ for the low level audio stages, (V9), and the small section is
the cathode bypass for the VOX Amp, (V10a). C110, 111 and 112, along
with R97, R98 and R99 form a phase shift network at the frequency of
oscillation. There are plenty of formulas for calculating values for
any reasonable frequency on the internet. ALL six pieces form the
network, you can't just change one or two! :-) There is a limit to
what you can do with the T-4X, because the audio tone is applied to the
MIC input for TUNE mode (whistling into the microphone) and so has to be
within the audio passband of the transmit filters. The tone is also
used to drive the VOX, detected and integrated to control the 6EV7.
The TR-4 series is a little different. It doesn't use the tone for
TUNE, only for SIDETONE and VOX. It is generated in the same way, C180,
C181 and C182, along with R126, 127 and 128.
--
73, Garey - K4OAH
St Charles, IL
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've thought about doing this in my Twins. Now that I've got a few extra
transmitters, this might be a good time to experiment. On the T-4X, I believe
half the can electrolytic is part of the sidetone r-c circuit.
Steve, W1ES/4
-----Original Message-----
From: Mark Nace<[email protected]>
Sent: Nov 1, 2011 10:14 PM
To: "Michael A. Kelly"<[email protected]>,[email protected]
Subject: Re: [Drakelist] Side Tone Adjustment for TR4CW Possible?
Mike,
I think it's an audio phase-shift oscillator, so guess you would need to change
some of the R-C values to get a lower freq.
Others will give better thoughts I am sure.
73
Mark
N5KAE
----- Original Message ----
From: Michael A. Kelly<[email protected]>
To:[email protected]
Sent: Tue, November 1, 2011 8:49:00 PM
Subject: [Drakelist] Side Tone Adjustment for TR4CW Possible?
Howdy,
I had a 12AV6 tube (V2) go soft and after replacing it the "chirpy"
audio for the side tone went away, (no chirp on the transmitted
signal, just on my end) but the new side tone pitch is higher than I
prefer. Is there an way to adjust the side tone audio to get it down
in the 700-750 Hz range? (not volume, but pitch)
Thanks,
Michael N4MAK
_______________________________________________
Drakelist mailing list
[email protected]
http://mailman.zerobeat.net/mailman/listinfo/drakelist
