[Elecraft] To PLL mod or not

[Rod N0RC]

Ron, et.al.,

After some thought, I'm not sure either of or methods can discriminate
between VFO/BFO drift. (I know mine can't ;-) Consider this:

Assume that the BFO is stable and constant, then if the VFO drifted, a
stable RX signal would shift position within the passband. A result of
the 1st mixer operation. And the RX tone would change, a result of the
mixer action between BFO (stable) and the shifted IF signal.

Now consider the VFO stable and constant, and a drifting BFO. Given a
stable RX signal, the drifty BFO would cause the RX tone to change.

Detection with ear or spectrogram detects the tone shift in either case,
but can't isolate the cause, BFO, VFO or both.

I think the only sure answer is a frequency counter at TP3 to measure
the PLL and/or TP2 to measure the BFO.

73, Rod N0RC


----- Original Message -----
From: "Ron D'Eau Claire" <rondec@easystreet.com>
To: "'Rod N0RC'" <rod@n0rc.us>; <elecraft@mailman.qth.net>
Sent: Saturday, November 09, 2002 11:06 PM
Subject: RE: [Elecraft] To PLL mod or not


> Rod N0RC, wrote:
>
> Wonder if I should leave well enough alone? Today I switched on my K2
> and while it was "cold" I zero beat WWV, the display read 10,000.02. I
> left the rig on, and four hours later zero beat WWV again. The dial
read
> 10,000.06.
>
> I didn't measure BFO drift, frankly I'm not sure how to measure it.
> Ideas? ______________________________________________
>
> My K2 exhibits similar L.O. stability in the shack. I'll probably
change
> those PLL crystals only because I bought the BFO mod kit and
Wayne/Eric
...
>  I'd suggest that the easiest way to tell if you have excessive BFO
> drift is to see how the signals sit in the passband of your narrowest
CW
> filter. For the first ten minutes or so, signals are actually down one