K3S, DDS/PLL induced drift, and precision frequency measurement

[Frank O'Donnell]

I recently noticed this blog post by WB4SON:

https://wb4son.com/wpblog/?p=3784

As he notes in the post, the phenomenon he discusses is not a flaw of
the K3S, but rather an intentional design feature included to keep
unwanted phase noise of the DDS as low as possible. But apparently it's
an effect that would need to be taken into account by anyone interested
in very precise frequency measurement at the sub-Hz level.

I wonder if there are any comments here, or thoughts on managing it
while doing FMT work? I just ordered a new K3S as a first-time user, and
FMT (as an absolute rookie) is one area I'm interested in.

Thanks and 73,

Frank O'Donnell K6FOD







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[Bob McGraw - K4TAX]

I use my K3S to participate in the twice year ARRL FMT.  I've always
come in with a measurement of better than 1 Hz.   Not at all bad for
amateur radio equipment.   And we must remember..........the Elecraft
K3S is amateur radio equipment. If you expect better, then I'd say take
the cost of your K3 or K3S and multiply it by a factor of 10X and that's
what you'll likely have to spend to get into the real world of frequency
measurements.

And in addition to the two events each year for the ARRL FMT, what does
one do the other 363 days?   That degree of precision is really not
needed for day in and day out operation.   Most ham transceivers are
likely to have errors of greater than 1 Hz. anyway.   Just don't believe
what the digital display indicates unless you have gone through a very
recent calibration.  I usually check and adjust mine about once per
month, on one of those days I'm bored, the bands are dead and it is
raining outside.    As to what others say regarding frequency, I take
those comments for no more than a grain of salt.

It is ham radio, enjoy it.

73

Bob, K4TAX



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