[Elecraft] Why is my K3 off frequency?

[Charles Tropp]

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.

-- 
*73, Charles N2SO*