[Elecraft] K3 TX delay

[Paul Christensen]

> I've also advocated to Elecraft in the past to make available RF delay
> settings below 8 ms for those of us who have fast QSK amplifier switching
> using vacuum relays or switching diodes. (My homebrew 6m amplifier T-R
> speed  is well under 4 ms, for example. The new Elecraft amp, I assume, 
> will be
> even faster.)

I believe the larger issue is keeping good oscillator stability (to prevent 
transmitter chirp) between T/R and R/T transitions.  That's a reason why 
Elecraft has not immediately implemented RIT in the K3 while in QRQ mode. 
Folks with a KRX3 can get around the RIT issue with the second Rx.  Even 
when the K3 does have RIT in QRQ mode, I believe Wayne indicated that the 
frequency delta will be quite restricted for this reason.

In the Ten Tec Omni Six series, CW chirp gets worse as the frequency delta 
between the Tx and Rx increases.  It can get pretty bad with RIT/XIT 
excursions nearing 10 kHz.  Most folks would not use RIT/XIT with such a 
large offset and this effect mostly goes unnoticed.  In the Omni V, T/R 
times are actually slowed down a bit with larger VFO A/B split excursions 
(no RIT/XIT in the V model) and chirp is non-existent.

I bring up the Ten Tec examples because the K3 is not immune from the same 
oscillator settling effects.  There's a definite  trade-off between T/R 
switch times and oscillator settling time when using a common oscillator for 
Tx and Rx

Paul, W9AC