From: "David Austin" 
Subject: [drakelist] Sidetone quality/pitch


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

Regarding CW mode:

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

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.

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.

Regarding SSB netting (spotting):

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

Apologies for the many questions in one posting!

73
David
(G4GTP)
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Just getting to grips with
operating my =
4C line=20
separates, having fixed a TX4C relay problem. (Low emission 6EV7. Thanks =

Garey) 
 
Regarding CW
mode:
 
1: If I operate with the receiver =
"unmuted" then I=20
effectively get a sidetone by direct reception of the TX output, which =
also=20
accurately reflects my transmitted carrier frequency (=3DCW pitch) =
relative to the=20
station I am working. The other advantage to this mode is a nice pure =
tone to=20
listen to (as opposed to situation in question 2 below). Is there any =
known risk=20
to the RX front end from operating it in this mode? Can't think that =
there would=20
be but thought I should check. 
 
Wouldn't it have been better to =
implement sidetone=20
in this way anyway, with a major reduction in RF gain "switched" in the =
the RX=20
front end by the TX relay when in TX,  together with preset AF gain =
to set=20
audio level? A few extra components in the RX, granted.
 

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