[Elecraft] Why is my K3 off frequency?

[Fred Jensen]

Hmmm ... I can just barely hear a 12 Hz difference on a CW note in an 
A/B comparison.  Your NCS must have extraordinary ears to hear that 
small a difference on sideband. Maybe he's just yanking your chain?

First off, 12 Hz at 50 MHz is essentially dead-on and I don't believe 
it's worth your time to mess with it nor do I believe it would ever 
matter.  But, Wayne published a procedure using WWV that will get you 
within 1 Hz at whatever WWV frequency you choose.  It used to be on the 
Elecraft web site but I can't find it now, maybe he'll speak up.  It's 
simple but you must go slowly.  Set the display to WWV's freq at the 1 
Hz display precision, select CONFIG->REF CAL, and adjust the REF CAL 
frequency for exact ZB.  While in REF CAL you'll see a number like
49.379682 in the display [that's what mine says, yours will likely be a 
little different].

When you are very close to ZB, you will hear the beat as a slow rise and 
fall in the noise or the WWV tone.  In my case, two adjacent REF CAL 
steps sort of "straddled" true ZB with the WWV audio tone pulsing about 
one cycle every 3 sec on either one ... ~0.333 Hz.  Get ZB during one of 
the minutes WWV isn't transmitting the audio tone.  Then, when the tone 
comes back, it's easier to hear the beat, and you are assured you're not 
trying to ZB the audio sideband.  Use the highest WWV frequency that you 
have a good S9 signal on.

There is one possible pitfall to beware of:  The 2.5 and 20 MHz WWV TX 
are 2.5 KW and appear to be linear transmitters.  On a panadapter, you 
can see the 100 Hz sub-carrier that carries the IRIG time code, and the 
tone produces the two sidebands you would expect.  The 5, 10, and 15 MHz 
TX appear to be Class C plate modulated and you will see additional 
sidebands at the harmonics of the audio tone frequency.  The second 
harmonic sidebands are only down about 15 dB from the fundamental 
sidebands.  All of the sidebands also show the 100 Hz sub-carrier.  
Using any of those WWV frequencies, you need to be extra careful that 
you're ZB with the carrier and not one of the sidebands.

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 3/23/2021 3:17 AM, Charles Tropp wrote:
> Hi,
> Last night my local ham club scheduled their first ever 6Meter Net and
> Roundtable for 50.135Mz. I operate USB very rarely, preferring CW for all
> of my Contesting and DX work. Last night the net control station advised me
> that I was 12Hz too high and that he had to use his RIT control to tune to
> me. When I turned on my XIT and transmitted down 12Hz I was right on his
> frequency. This was confirmed by other callers as well. I have also heard
> this problem mentioned in the past when checking into occasional 75M nets.
> Is there an adjustment that I can or should make aside from using my XIT?
>
> Thanks for any assistance you can provide.
>