Thanks Don. So here's another question. My first step was to remove C2, which effectively removes the varactor (D3) from the equation. I was still observing an excessive amount of drift. Doesn't this rule out the voltage regulators as the cause of this problem?
73, -Matt W6ZBA On 5/5/11 7:19 AM, "Don Wilhelm" <[email protected]> wrote: > Matt, > >I would first suspect the stability of the voltage regulators. That VFO >is tuned with a varactor, if the voltage changes, the frequency will >change. If that does not settle it down, I would wind L1 on a new core >on the suspicion that the present one is more temperature sensitive than >usual. > >73, >Don W3FPR > >On 5/5/2011 1:40 AM, Matt Scholz wrote: >> Hi - >> >> I am trying to reduce my K1's VFO drift to an acceptable level. The VFO >> frequency drifts up at a rate of about 30Hz/minute (after a 5 minute >>warm >> up). Even after one hour, the drift is still about 15Hz/minute. This is >> too much, obviously. >> >> I have been trouble shooting this with the help of Gary, AB7MY. So far I >> have done the following: >> >> * Removed C2 to isolate D3 from the rest of the VFO circuit. No change. >> * Replaced all three VFO poly caps (one at a time). See above. >> >> I was wondering if anybody had any ideas on how to further trouble-shoot >> and resolve this issue... >> >> Thanks in advance and 73, >> >> -Matt / W6ZBA >> ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
