[Elecraft] Sync AM and checking VFO accuracy using WWV

[Fred Jensen]

Fair question ... actually a good question.

Short answer: On vintage receivers, the VFO freq [the local oscillator 
that heterodynes to the IF freq] is switched for each band ... except of 
course if it's a Collins radio.  It's a single dial with multiple fixed 
scales but multiple frequency determining networks.  Calibrating one to 
WWV has no bearing on any of the others, and your example is correct.

For a K3 [and all like it], the "VFO" is synthesized from a single, 
non-switched source regardless of band.  Get it within 1 Hz at 80, and 
it will be within 2Hz [or so, it's digital after all] at 40. So, you 
want to to do the adjustment at the highest possibly frequency ... all 
the lower ones will be *at least* as good.

A critical factor in this procedure is that the WWV signal strength 
needs to be hign enough to discern the zero beat clearly.  I did mine at 
20 MHz when there were lots of sunspots.  At the end of 2016, you may 
need to settle for a lower WWV.  The difference will be tiny in any case.

73,

Fred K6DGW
- Sparks NV DM09dn

- Northern California Contest Club
- CU in the Cal QSO Party 7-8 Oct 2017
- www.cqp.org

On 12/17/2016 9:17 PM, Brian Denley wrote:
> Fred, Don: I ask because I am curious.  On any older receiver,
> calibration at 20 MHz would not guarantee cal below that ( or at any
> other frequency ).  One could be 5 hz high at 30 MHz but 10 hz low at
> 7 MHz.  Why is the K3 different?
>
> Brian Denley KB1VBF Sent from my iPad