[NLRS] Re: (LONG)10GHz Operating procedures ?

[Doug Reed]

At 01:43 PM 7/4/2003 -0500, John P. Toscano wrote:
>Because each of them is adjusting 
>both transmit and receive frequencies each time, and because each of 
>them is hearing a signal Doppler shifted HIGHER than it is transmitted, 
>they keep "walking up the band" to stay in tune.  If they each left 
>their transmitter frequency alone, and adjusted only their receive 
>frequency, they would have stayed in place (other than oscillator drift).

Hi John.

Personally, I don't think of the problem as a matter of Doppler shift, and
only minimally as a problem of LO drift. It is primarily a matter of tiny
shifts in LO frequency from RX to TX and possibly shifts in IF radio
frequency. For whatever reason it happens, if station 1 retunes his main
dial while Station 2 is transmitting, station 2 will have to retune when
station 1 replies. If BOTH stations are using the main dial to retune each
time, you get exactly the "walking up the band" problem you describe. If
EITHER station is using RIT, the retuning stops right then. And of course
they want to retune because they both want to hear a familiar voice rather
than Donald Duck.....

Again, I primarily blame it on the hardware more than anything else. i.e.
does your IF radio shift in frequency as the battery voltage drops? The
voltage will change as you go from RX to X and back. Maybe the transverter
LO changes 500 Hz from RX to TX? It is small changes like that which I
believe cause the problem, not Doppler..... Doppler will have a similar
effect but I don't think we're seeing it in this application. 

And when you're using RIT, be sure to reset it to zero after each QSO or
group of QSO's! Otherwise YOU will be the one causing the problems because
your TX frequency will not match your RX frequency. 

Last year it seemed to me that most people had very little LO drift over
the day. I think just about everyone made the wiring changes required to
make sure their transverter always had power and therefore the drift was
minimized. It was normal for just about everyone to be on frequency or very
close to frequency after a move. And when everyone tuned their RX to the
QSO in progress, there was very little "chase me" tuning confusion during
the Q's. It made things go much quicker..... 

73, Doug Reed, N0NAS.