[Elecraft] Frequency calibration - again

Sun Aug 24 09:00:01 2003

Last night I had another bash at calibrating my K2 using an 
alternative method similar to GU3MBS's Spectrogram method but using a 
program called Argo originally designed for reception of slow CW 
(QRSS) on 136kHz. This allows one easily to see and adjust signals 
seperated by 1Hz or less. I will give more details later, with a link 
for the software, but a couple of things I have noted first.

The first thing I noticed is that it said my sidetone, set to 700Hz 
in my case, was at 710.3Hz, and a check with my counter confirmed 
this. What implications does this have in using the sidetone beat as 
a guide for exact tuning, and is this a common problem?

The basic problem with adjusting C22 is that it is very difficult to 
set it precisely to frequency at 20MHz - it is easy to get it within 
50-100Hz, but anything better is a natswhisker of an adjustment. I 
did manage to get it once within 2Hz, but it didn't stay there, any 
mechanical movement and it will move off by 10-20Hz or more.

Of course I am still unsure how accurate the 1MHz reference in my 
counter is. End result last night is that I am back to where I was 
with the dial reading around 30Hz high on all bands.

I intend to have another bash, but it really does seem to get the 
1ppm accuracy claimed is hard to achieve in practice.

More to follow (sorry to bore some of you..).

73 Dave G3YMC

73 Dave G3YMC

[email protected]
http://www.dsergeant.btinternet.co.uk