K2 and NaP3 IF offset values

Posted by K8AC on Nov 14, 2015; 4:15pm
URL: http://elecraft.85.s1.nabble.com/K2-and-NaP3-IF-offset-values-tp7610348.html

I've been using my K2 with LP-Pan and NaP3 for a few months on the lower bands and just recently got on 20 and 15 meter CW with it.  I found that the offsets you specify in NaP3 were considerably different on 15, 12 and 10 meters while that for 20M was just a bit off from the lower bands.  17M offset was the same as the lower bands.  For example, the global offset required on 80, 40 and 30M is 1170 in my case.  For 20M, it's 1200.  For 15M it's (-285) and (-330) for 10M.  

When I say the "offset required", that means the value I need to specify in order for the NaP3 center frequency indicator line to be exactly in the middle of a received CW signal.

Not quite sure why the offset difference - obviously the IF signal is not exactly the same for all bands, but why not?