[Elecraft] K3(s) main oscillator calibration

[Wes]

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