[Elecraft] K3EXREF question

Kevin Stover kevin.stover at mediacombb.net
Mon Mar 7 20:10:45 EST 2016


I believe that is the way it is.
53/1000 of a hertz over an hour?
I'd give that up all day everyday for the spectacular lack of phase 
noise in the K3s or K3 with the new synth.
It's not a cesium clock.

On 3/7/2016 8:02 AM, David Anderson wrote:
> I -think- the way it works is that when the K3EXREF is locked with the external frequency standard on 10 MHz, this is used to measure the frequency of the TCXO. The value of that frequency measurement is then put into the K3 REFCAL setting. If the TCXO drifts slightly as they all will, then the frequency difference is detected and the value in REFCAL is changed to match, hence keeping the frequency of the K3 correct, without actually phase locking the TCXO to an external reference which could degrade the low phase noise performance of the K3's synth.
>
> Basically the K3EXREF is doing the same thing automatically as you would manually when doing the calibration, by measuring the TCXO frequency and storing that value in REFCAL. The K3EXREF acting a frequency counter with a high stability external 10 MHz reference.
>
> Hope I have that right.
>
> So, it would be normal for the value in REFCAL to change as things warm up even with the external reference into the K3EXREF, because the TCXO is not locked, just measured.
>
>
> 73 from David GM4JJJ
>
>


-- 
R. Kevin Stover
AC0H
ARRL
FISTS #11993
SKCC #215
NAQCC #3441


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