[Elecraft] K2 Frequency accuracy by band

[G3VVT at aol.com]

Jeff,

Take care when measuring and adjusting the 4MHz crystal in the K2 with an 
external device except with reference to WWV. I got my fingers burnt in this 
direction by the counter I was using the Racal Dana 9915M, even though fairly 
accurate with it's ovened clock caused error by loading the 4MHz oscillator at the 
C22 test point. Ended up having to isolate the external counter with a X 10 
high impedance scope probe to get an accurate measurement. You will note the 
probe for the K2 internal frequency counter is isolated to a degree by only 
having a 10pF capacitor in series with the test probe.

The IFR-1200S service monitor is too far out of calibration to be relied upon 
for the precise measurements you are calling it to do. At my last place of 
work before retirement the Cal Lab insisted on recalibrating our communication 
service monitors at 6 month intervals so the IFR you used may or may not be 
accurate after that extended length of time. Probably OK to use it as a reference 
particularly if you can check it against an off air standard such as WWV. Not 
sure if the IFR-1200S is sufficiently sensitive to receive WWV direct. The HP 
8920A we used and even the old Cushman C6? was even in the deserts of Arabia 
with a suitable antenna. The Marconi 2955 communication monitor I bought after 
returning to the UK does not have the sensitivity to do this test and the 
cost of recalibration would be prohibitive. This means I also have to be careful 
in placing absolute reliance on measurements now the calibration has also long 
expired.

Bob, G3VVT
K2 #4168