Curran, here's a reversible no-holes mod that I've done to my C-21's to
simplify that procedure.
I replace the zero-beat button (those are lousy buttons anyway) with an
illuminated *push-on/push-off* switch. You can get them from Allied in
various colors including red or clear.
Anyway, wire it so the LED comes on when the switch is closed and the
VFO is in zero-beat mode
Now, when you're going to cruise the band, you first set your offset
control just a little bit to one side of zero-beat or the other. Then
push your new zero-beat switch so that the LED in the button lights up
(meaning the offset is disabled).
When you hear a station you want to call, just tune the signal to
zero-beat. Then press the zero beat button again (the light goes out
and the offset is turned back on).
1. Now his desired signal will be audible (sometimes it's easy to lose a
signal with the old switch set-up)
2. You can go ahead and tune the offset control wherever you want it.
3. Your TX will be already be zero-beat with his signal.
4. Give him a call.
It no longer takes both hands to do the "hold button/tune-for-zero-beat"
operation, and the LED keeps you apprised as to whether you're in
zero-beat mode or not.
You can get switches that look pretty good, round or square. I replaced
the power level switch on mine with a matching SPST momentary contact
switch, just to make it look nice.
73,
Tom
On 1/27/2010 5:54 AM, Curron HILL wrote:
Can some one explain how to use the zero beat and offset controls on a Century
21? It is a DC receiver and different than I have ever used. I know that
pressing the zero beat button disables the Offset control. I know that you
tune the CW sound until it goes down to point that you can't hear it. If you
continue to tune you hear the CW begin agian going up in pitch. So you back up
until it can't be heard again. Then you tune the Offset until it has a
pleasant sound. The offset it tuning the reciever only and the transmitter
stays zero beat correct? Is it that simple? Or do you have to anything about
which sideband the band works from? Why the +/- on the offset? is it so that
you can listen to either side of the CW from the Zero Beat point and maybe get
away from other transmissions on one side of zero beat or the other to help
eliminate QRM?
Thanks, and 73 Curron KB3DRW
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