I mentioned in a previous post that one of the “hidden features” of the PL-990 series is the ability to calibrate the radio so that the frequency display is correct when say, you zero-beat an AM broadcaster/carrier in SSB mode.
For normal AM broadcast listening, you’d never notice the frequency discrepancy on the display. When I used the PL-990 in ECSS mode, though, my frequency display is a few Hertz off pretty consistently across the spectrum.
Our friend Gilles Letourneau (at the Official SWL Channel) recently told me that after a couple hours of tinkering with his PL-990 last weekend, he was able to calibrate it but was so deep into the process, he wasn’t able to document exactly how he achieved it. Of course, now that it’s accurate, he doesn’t want to inadvertently harm the calibration. I don’t blame him.
Big news is he’s confirmed that it’s possible.
I’m curious if any PL-990 or PL-990x owners have successfully calibrated their receiver. If so, please consider sharing your procedure with us!
UPDATE
Gilles comments…
“Tune a strong signal in AM .. like WWV then use LSB USB modes to fine tune the receiver as close to zero beat as possible. Then simply press and hold the USB key until display light flashes two times … you will be all set and calibration will work !”
Press the pl-990x bottom reset button to keep the stored frequency intact. I wonder if the calibration information is maintained without any changes.
What I have noted is the calibration(zero beating)of the proper demodulation on the PL-880, PL-990, and the H501x seem to vary in effectiveness, wherein for instance some folks experience less than optimal SSB on their sample PL-880, my sample easily calibrated zero and has tenaciously maintained it for long periods across all am bands including both USB/LSB.
On the other hand some folks feel the PL-990, or the H501 to be the ne plus ultra of SSB reception, I have had less then stellar results calibrating them compared to that PL-880. I can get the PL-990 to zero and maintain it but not nearly as stably as its PL-880 stablemate, whilst the H501 steadfastly refuses to calibrate effectively, and never has done so across all am bands and SSB, continually requiring immediate re-zero just tuning from frequency to frequency within the very same band!
Nonetheless, the PL-880, and PL-990 are proving very effective on SSB, and both seem to take to calibration much more robustly than the larger H501….
these days here in Greece we got some kind of overheat, outside 38C, at room did not switched on the air condition so 31C inside … pl-990 was need to calibrate again by – 9Hz .(due to heat) .. example was at 13, now is 4 … or if was 0 it needs -9 … when heat go away (in few days) will need again calibration … is not a fault, tecsun says it may needs from time to time readjustment
Thanks for the credit, Gilles — still unclear is whether you have to do both USB and LSB to attempt to bring both to zero and whether this procedure holds for a significant distance on the bands i.e. With the 880 I recall having to recalibrate a few times from bottom to top of bands.
Gilles just posted this new video “How to Calibrate frequency of the Tecsun PL-990x to have perfect SSB frequency readout” on his YouTube channel.
Finally procedure that works !
Tune a strong signal in AM .. like WWV then use LSB USB modes to fine tune the receiver as close to zero beat as possible. Then simply press and hold the USB key until display light flashes two times … you will be all set and calibration will work !
Thanks, works for the PL-330 as well!
PL 330 calibration demonstration
https://youtu.be/UEjJdCCq-Cw