All synthesized radios tune in steps. The difference between them is some are
smaller steps than others. Eleven years ago I offered a fourth method for
calibrating the reference frequency in a K3. (I suspect, but do not know that
the K3S is different.) See:
http://elecraft.365791.n2.nabble.com/Ref-Osc-Cal-Method-4-td2595451.html
After reading about my observations another ham queried Wayne and he responded
with an explanation of the frequency generation in the K3. Once again, I don't
whether this applies to the K3S. Perhaps Wayne will let us know. Nevertheless,
the tuning step sizes are different for different bands with the higher bands
having greater step sizes, i.e. less accuracy. I-F BW/Shift requires changing
oscillator frequencies at I-F ("BFO") with commensurate changes in the LO.
Since the LO has different step sizes on different bands, changes in the beat
note (that I observed) do occur.
The K3(S) is a great transceiver, it isn't a great frequency meter.
Wes N7WS
On 6/6/2020 2:42 PM, Dave Cole wrote:
Hi,
As the other station siad, you will have Doppler issues. Also the K3 tunes in
steps, which make sustained .1 hz accuracy a dream, not attainable. It looks
to tune in .25 Hz., or larger steps. I am going from memory here, so it may
be something different.
I wanted to use my K3 to watch Ionospheric shifting, via Doppler shifts, from
WWV. I am unable to as a result of the method Elecraft chose for tuning.
I have the TXCO, and that just provides a reference for the radio, it does not
make the steps go away...
I was quite disappointed when I discovered this, but, the good stuff in the
rest of the radio makes up for that small loss. I'll buy some stable rig that
uses analog tuning.
73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist
ARRL Asst. Director, NW Division, Technical Resources
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