[Elecraft] Checking VFO accuracy using WWV

[brian]

Expectations may be too high.....

All these WWV methods assume there is no Doppler shift present on the 
WWV signal.  Other things to consider: TCXO drift, synthesizer 
limitations and new synthesizer quirks.

During disturbed times, Doppler could be 1 Hz or more.
Unfortunately, the Doppler shift present depends upon just about 
everything-- location, time of day, atmospheric reflecting layer 
heights, path, the list goes on.

Keep in mind the new synthesizers add an additional quarter Hz (+/-) 
uncertainty.  The syncing of the SI570 to the master oscillator produces 
sawtooth jumps of that magnitude, sometimes more vs time.
There are also band to band variations introduced by limitation in 
finding exact synthesizer divide ratios.  Old synthesizers showed many 
Hz deviations from band to band and as one tuned up the band.  These 
variations are much smaller with the new synthesizers.

Then there is drift.  If you are not using XREF, you will experience 
maybe 10 Hz or more warm up drifts.  The high stability oscillator takes 
about four hours to reach its most stable point.  The standard 
oscillator reaches that point a few hours earlier.

The old engineer cautioned: "Never believe the last digit displayed in 
any device".  In this case, don't expect to be within 1 Hz on all bands, 
all frequencies at all times-- no matter what calibration method you 
use.   Look at the K3 specs.  Nowhere will you find an expectation of 
such accuracy.

73 de Brian/K3KO

On 12/18/2016 12:40 PM, K9ZTV wrote:
> The R.L. Drake Company referred to the zeroing or beating indicators as "canary chirps,"  the goal being to slow the "chirping" until there was a steady tone indicating you were then dead-on.  I still find that the most descriptive way to tell someone how to identify the pulsing when doing the Reference Calibration against WWV in a K3 (at the highest frequency you can copy them). The trick is to get the right balance in volume between WWV's main carrier tone and the K3's sidetone so you can hear the "chirps."
>
> Kent, K9ZTV
>
>
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