[Elecraft] K2 frequency calibration - stuck

Ron D'Eau Claire [email protected]
Mon Jan 20 00:54:01 2003


Ron:

I think you mean 20MHz not 25 MHz.
73
Jim  K4ZM

WHUPS! I SURE DID Jim! 

The fifth harmonic of 4 MHz is a LOT closer to 20 MHz than 25 MHz <G>.
Thanks for catching that!

While I'm at it, I'll reiterate that the biggest disadvantage of that
method of setting C22 is that WWV runs relatively low power on 20 MHz,
so a lot of ops can't hear it at any time. But if you can hear it, it's
a very easy way to get the clock VERY close. After all,  any error you
have zeroing it at 20 MHz is divided by 4 at the actual oscillator
frequency... that is if you get it only with in 5 Hz of "zero beat" at
20 MHz the actual oscillator frequency error is 5/4 or 1.25 Hz! 

It won't hold that accuracy over time, of course, but it's only needed
until one runs CAL PLL. Once the new values have been calculated and
stored, using the 4.000 MHz clock as the reference, it doesn't matter
what the 4.000  clock frequency does... until the next time something is
changed that requires running CAL PLL again <G>

Thanks for catching my faux pas!

Ron AC7AC