From: "Gerry" 
Subject: RE: [drakelist] Sidetone quality/pitch


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I'll take a stab at your first two questions. In the first instance, you
should be able to add a pot in parallel with the mute socket. When
transmitting, you could adjust the value to a point where you can hear =
the
note. Receive mode would not be affected. I've done this before without
damage to the receiver. Others may have had different experiences. Now =
for
the side tone. I have two C lines and they both have lousy side tones as =
you
described. I think it is because of an impedance mismatch between the =
side
tone output and the audio transformer. The audio section of the R-4C is =
the
same one Drake used in the 2-C receiver. The 2-C companion transmitter, =
the
2-NT has an excellent side tone to match the AF transformer in the 2-C.
Apparently, Drake made no provision for the differences in impedances in =
the
C line. The B line as well as the TR-4 have excellent side tones.

=20

-----Original Message-----
From: owner-drakelist{at}www.zerobeat.net
[mailto:owner-drakelist{at}www.zerobeat.net] On Behalf Of David Austin
Sent: Friday, February 20, 2004 3:52 PM
To: Drakelist
Subject: [drakelist] Sidetone quality/pitch

=20

Just getting to grips with operating my 4C line separates, having fixed =
a
TX4C relay problem. (Low emission 6EV7. Thanks Garey)=20

=20

Regarding CW mode:

=20

1: If I operate with the receiver "unmuted" then I effectively get a
sidetone by direct reception of the TX output, which also accurately
reflects my transmitted carrier frequency (=3DCW pitch) relative to the
station I am working. The other advantage to this mode is a nice pure =
tone
to listen to (as opposed to situation in question 2 below). Is there any
known risk to the RX front end from operating it in this mode? Can't =
think
that there would be but thought I should check.=20

=20

Wouldn't it have been better to implement sidetone in this way anyway, =
with
a major reduction in RF gain "switched" in the the RX front end by the =
TX
relay when in TX,  together with preset AF gain to set audio level? A =
few
extra components in the RX, granted.

=20

2: In the above situation I operate with sidetone (anti-vox) turned to =
zero
to mute the sidetone. If I do use sidetone (RX muted of course) I find =
that
the sidetone does not sound very pure (a bit "raspy" or rough sounding). =
Is
this normal or should the sidetone sound like pure sinewave output? =
Also, is
there any way of altering the sidetone frequency? I find it a little too
high pitched for my taste. This is the advantage of method 1 where you =
can
choose your own "sidetone" frequency by adjusting the incoming signal to
taste on the RX, then "netting" TX VFO to same frequency in Spot mode.

=20

Regarding SSB netting (spotting):

=20

Can anyone explain the source of the canary "warbling" sound when =
netting
the TX and RX ? Is it the sound of the two carrier oscillators beating? =
If
so, why is this not audible as a pure sinewave beat frequency, with a =
smooth
reduction to zerobeat as the two frequencies coincide, instead of the
somewhat "unstable" sounding canary sound?=20

=20

Apologies for the many questions in one posting!

=20

73

David

(G4GTP)


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