Notes on calibration of my other QMX* devices.?? Some (hopefully) useful info:
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Calibration of my QMX high-band:
- all completed normally and looked good, except 30m phase error had an irregular shape, large downs and ups near the beginning similar to the irregular shapes that occurred with earlier versions.
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Calibration of my QMX+ rev2:?
- The 160m phase error plot stopped very early, at about DAC=750.? The symptoms were exactly the same as the 80m on my QMX low-band, where the calibration DAC values started at 2xxx rather than 0.? Retries do the same; it never completes.
- The 20m phase error plot stopped early, about DAC=1500.? But one retry allowed it to complete.? I didn't see the DAC values on the first run to see if they started high.
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Calibration of my QMX+ rev3 (done overnight, so cooler temperatures):
- 40m, 30m, and 6m PE calibration stopped early; 40m at DAC~1000,? 30m at DAC~1200, and 6m at DAC~700.
- a single 'O' retry fixed the 40m and 6m PE sweeps.
- 'O' retries did not fix the 30m; it stopped at the same place, repeatable - See series of screenshots below.?
-? Note: 1) the new startup measurement messages are not present;
-? Note: 2) it stops after a "change greater than 30 degrees" message.? The change >30 degrees was in fact a measurement of 0.1 following a measurement of 359.8, so it was a phase rollover, not a large change.? So the change from near 0 to 359.7 at DAC=250 worked, but the opposite change from 359.8 to 0.1 at DAC=1250 did not work.
- I power-cycled the QMX+ (first power-cycle since start of calibration) to see if behavior would change on 30m; no change.?
- 160m USB IMD optimization flatlined with all values at 0 (I never saw that before).? A single 'O' retry fixed this (I did this before any of he above retries).
- All other PE and IMD completed and looked to have reasonable values.
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I hope this info is useful in some way -
Stan KC7XE
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