Gary, I had the same problem. After 3 years, I had to replace the TCXO which had clearly become defective.
I still need to recalibrate periodically. I don’t operate HF, so hearing WWV is sometimes difficult. A good way to calibrate is to have a local, who is dead-on calibrated, send CQ on FT8. You can adjust the ref cal to get it right. 73, John WA1EAZ > On Dec 6, 2019, at 2:24 PM, Edward R Cole <[email protected]> wrote: > > To add a little to what Wes said: > > The K3 TCXO rest freq is 49,380 KHz. It is a temperature corrected > oscillator so will still drift with radio warm up but less than a > non-compensated oscillator. So best to calibrate after at least 30-minutes > warmup. If you have the 100w model K3, there will be some temperature drift > when transmitting (varies with mode and frequency band). > > I have the EXREF installed with the TCXO-03 and that holds my 50-MHz signal > within 3 Hz. But if you check the TCXO frequency (CONFIG: REF CAL) you will > see the frequency drift. Mine seems to top out at about 49.380.090 and then > hold within a few .001. > > The EXREF takes the need for periodic re-calibration away. But your 10-MHz > reference needs to be very accurate/stable. I use a surplus OCXO that needs > re-calib about every 4-6 months (usually only 1-Hz drift). My OCXO runs 24/7 > to avoid warm up drift. > > Hope that helps. > > 73, Ed - KL7UW > > From: "Gary Peterson" <[email protected]> > To: <[email protected]> > Subject: [Elecraft] TCXO drift and calibration > Message-ID: <C8C8661341DC47FCB5BF558A94B08417@WIN7LowProfile> > Content-Type: text/plain; charset="iso-8859-1" > > Last February, I purchased a factory assembled K3S including a 1 ppm TCXO. > The transceiver is serial number 11803 and the firmware was updated on May > 5th of this year. > > Last July, I noticed that many of the signals on 50.125 MHz sounded as if > they were a bit off frequency as they were higher pitched. This led me to > believe that the reference oscillator may have drifted, possibly due to > crystal aging. > > Subsequently, I used method 2 and WWV, as described on page 53 of the > Elecraft K3S manual. The REF CAL frequency was lowered from 49.999.996 to > 49.379.448. That seemed to make the signals on the 6 meter calling frequency > sound like they should. > > A few days ago, I caught a six meter opening and signals on 50.125 sounded > higher pitched again. I repeated the reference oscillator calibration again, > using method 2. Now, the REF CAL frequency is set to 49.379.110. I have not > had the opportunity to hear any six meter signals, since I changed the > reference oscillator. > > I am wondering if the REF CAL frequency change that I have seen in less than > a year is normal, or whether I have a TCXO problem. > > Any thoughts would be most appreciated. Thanks in advance for any time taken > to reply. > > Gary, K0CX > Rapid City, SD > > > 73, Ed - KL7UW > http://www.kl7uw.com > Dubus-NA Business mail: > [email protected] > ______________________________________________________________ > 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 > Message delivered to [email protected] ______________________________________________________________ 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 Message delivered to [email protected]
