[Swan] Re: RIT and the 270

[Mark Shaum]

> From: "KEN CUBILO" <kencubilo at verizon.net>
> Subject: [Swan] adding rit control to cygnet 270
>
> Has anyone added rit control to their rigs? I would like to add it to
my
> cygnet 270. Correct me if I am wrong but could I not vary the
capacitance of
> c1501 in the carrier osc circuit and get rit on cw that way?
>
> Ken W8WLC

Switching the carrier osc frequency a bit between xmt and rcv may help
bring actual transmitted and received frequencies closer together (the
tx should be offset by whatever tone you prefer to listen to and/or the
sidetone frequency) if your situation is that your cw replies to
stations are off frequency, but it wont provide true RIT.

To provide RIT, a method to vary the vfo frequency only when in receive
mode is needed.  Most rigs of this era used a variable voltage across a
diode (acting like a variable capacitor) tapped into the vfo tank
circuit at some appropriate spot that would be adjustable in receive
mode for plus/minus a couple khz.

Swan, Heath, Collins, all seemed to shy away from RIT circuitry until
the mid-70's or later.  Not having it is an irritation in SSB round
tables as well as CW.  I added RIT to my SB-101 decades ago by
"borrowing" the LSB/USB (or maybe the RTTY input, I forget) offset
voltage point on the LMO to use as a RIT voltage input.  Dial
calibration shifted on one sideband as a result, but having RIT on CW in
return was an acceptable tradeoff to me.

73!  Mark K9TR