[Elecraft] To PLL mod or not

Mon Nov 11 11:50:59 2002

Rod
If you are looking at a received signal or marker with Spectrogram, center
the signal in your narrowest passband.

If the vfo is stable and the BFO is drifting, the signal should stay put
within the passband (determined only by vfo and filter) but the pitch should
change.

If the vfo is drifting, the signal will move in the passband and the pitch
will change.

This should allow you to determine whether vfo or BFO is drifting.
73, Bob N6WG

-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Rod N0RC
Sent: Sunday, November 10, 2002 10:07 AM
To: [email protected]; [email protected]
Subject: Re: [Elecraft] To PLL mod or not

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" <[email protected]>
To: "'Rod N0RC'" <[email protected]>; <[email protected]>
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

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