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Hello Hans, hello guys,

I designed my QRX+ for a supply voltage of 9V by appropriately designing the output transformers.
I have now also tested the current beta firmware 1_01_003. I assume that the choice of operating voltage is irrelevant for the firmware.
Of course, the required calibration was also performed before the tests.
Optimal parameters were found in all individual calibration runs.
During testing, however, I noticed that the PD parameters on my QRX+ behave differently. The effect of the software switch for phase pre-distortion is reversed,
i.e., the ID3 spacing improves when phase pre-distortion = OFF. The CESSB and amplitude pre-distortion parameters have no effect.
I also noticed that with a drive level of 900, in addition to the highest output power, the best ID3 spacing is also achieved.
Reducing the drive level steadily worsens both parameters. A dependency of the curves as shown in the diagram could not be observed.

Any speculation as to why the firmware on my QMX+ exhibits this behavior?

vy 73
Juergen dl9jgo