Topics

Frequency Calibration

KD
 

I've run through the frequency calibration process in WSJT-X and up until the past week or so felt good about my rigs frequency.  However, I've worked a few stations that report I'm off frequency on 2M by anywhere from +1500 Hz to -600 Hz.  The -600 Hz report was from an op running with a GPSDO as was the +1500 Hz report.  I've had a couple of reports in the -200 to + 200 Hz arena from ops that have "calibrated" rigs.  So my question revolves around how to really determine if I am off frequency and if so, by how much.  I had my rig, a TS-2000, serviced in August, and the tech said it was now off at 10 MHz by 0.3 Hz.  The WSJT-X calibration process adjusts my 2M frequency by approximately 12 Hz, and I really question if I am off frequency.

KD - N5KS DM95be

John Klem
 

KD - The WSJT-X FreqCal process should reliably get you very close unless your rig is drifting badly.  You might try FreqCal at cold start, after 1 hour on receive, and after some high-duty-cycle transmitting to get your rig hot, and see how much they differ.

You can use some abbreviated version of the FreqCal process, maybe even just looking at WWV at the highest frequency you can hear well, as a sanity check.  I have a relatively new TS-590SG with TXCO and can clearly see the temperature drift from cold start this way, but it's not bad enough to produce the biggest errors you describe.   I believe you can safely assume that the error scales with frequency, so if WWV on 15 MHz appears off by 5 Hz, your frequency error on 2 m will be around 50 Hz.

Just let me know if you want further details.

John AA5PR

KD
 

Thanks for the info John.  I don't think my frequency is drifting that much, if at all.  I question the reports I received due to the wide range, both positive and negative.  The rig has been on for about 5 hours now and on 20 MHz WWV I'm off about 0.37 Hz on average.  At 10 Mhz I'm off on average 0.22 Hz.  If I'm calculating correctly, that slope would infer that I would be off about 18 Hz at 144 MHz.  For MS work that should be more than adequate.

73 de N5KS - KD
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