[Elecraft] TCXO drift and calibration
You were very correct about my first number being bogus. I misinterpreted my notes. I should have been more careful, before posting. These are the correct REF CAL numbers As it came from Elecraft, it was set to 49.379.766 July 10 of this year, I changed it to 49.379.448 On November 30, I changed it to 49.379.110 Each calibration was done after the radio had been on for a couple of hours. I'm guessing that the TCXO drift is due to crystal aging and the amount of change will diminish with radio on time. Thanks to all who took the time to respond. Gary, K0CX “Your first number is bogus, but generally speaking if your other numbers are correct, that does seem excessive.? That said, crystals do age and some of this depends on power on/off cycles... I recently ran some drift tests and found that it takes about 25 minutes for my reference to settle to a point limited by measurement jitter... Wes N7WS” __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] TCXO drift and calibration
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 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" > To: > Subject: [Elecraft] TCXO drift and calibration > Message-ID: > 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: > dubus...@gmail.com > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to jstengrev...@comcast.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] TCXO drift and calibration
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" To: Subject: [Elecraft] TCXO drift and calibration Message-ID: 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: dubus...@gmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] TCXO drift and calibration
Your first number is bogus, but generally speaking if your other numbers are correct, that does seem excessive. That said, crystals do age and some of this depends on power on/off cycles. I'm now to the point of leaving my K3S powered continuously. I recently ran some drift tests and found that it takes about 25 minutes for my reference to settle to a point limited by measurement jitter. There is an initial positive increase of a few Hz at power up (at room temperature) then a non-linear decrease of about 25 Hz. (Direct measurement of the synthesizer output with a FA-2 counter by BG7TBL, with a Bodnar GPSDO reference) Wes N7WS On 12/4/2019 1:33 PM, Gary Peterson wrote: 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 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
[Elecraft] TCXO drift and calibration
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 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
