> The intention is to ultimately leave only one valve in the signal
> line -
> the RF amplifier - to preserve the R4C's permability tuning.
Hi Steve and all...
There is one mod that might be useful to some, and that is a RIT control
on the front panel of the R4C *if* you are using the R4C
as a transceiver with say, the T4XC. I relocated the phone jack to
the rear panel and installed a high quality, "2-watt", linear taper pot
in
its place.
Basically (and if I remember correctly...it's been awhile)...the
mod uses a 1n914 diode that is back-biased as a variable capacitance
diode inside the PTO box. Then there is a solid state switching circuit
that basically changes the voltage on the diode (and thus the frequency)
when switching from receive to transmit....no clicks, chirps, etc.
As I recall what I had there was a rather crude circuit that could
be made much more eligant. Tuning was about +/- 7 khz.
It was necessary to recalibrate the PTO dial
becasue the PTO circuit is VERY sensitve to capacitance;
also the tuning (at least on mine) is no longer perfectly linear...
not a problem though becasue of the built in calibrator if one
wants to spot check the "exact" frequency.
The mod has remained stable and trouble free for at least 20
years!!
>
> Once the rebuild has been completed and works to our satisfaction,
> it will
> be written up for publication.
OK great!!
73!
Charlie, N0TT
________________________________________________________________
Sign Up for Juno Platinum Internet Access Today
Only $9.95 per month!
Visit www.juno.com
|