4 MHz oscillator is too high in frequency (K2)

Posted by Sverre Holm (LA3ZA) on Apr 21, 2014; 2:36pm
URL: http://elecraft.85.s1.nabble.com/4-MHz-oscillator-is-too-high-in-frequency-K2-tp7587585.html

My aging K2 (#2198) has developed a curious symptom in that the 4 MHz oscillator cannot be adjusted lower than about 4,000,000.55 kHz. It has probably been like this for a while and my BFO settings have probably been done with the incorrect reference. I discovered it by observing that the indicated frequency was about  0.75 kHz off.

Questions to the group:
1. Has anybody experienced anything like this, and can it be blamed on aging of e.g. the crystal or on some of the capacitors in the circuit? (BTW I have the KI6WX mod of the oscillator circuit http://mailman.qth.net/pipermail/elecraft/2003-August/022687.html which has worked well before)

2. How can I do a quick fix? e.g. by reinstalling C21=33 pF instead of the 10 pF of the mod above - or some other idea for a fix?

73
Sverre