开云体育

I don't know if any of you has noticed anything similar: while performing the SSB calibration on a band-by-band basis (using the "O" option) I noticed that at the end of the USB/LSB IMD Optimization step of each band, the power out is not put back to zero. I read between 0.5W and 1.2-1.5W on some bands, and again, this is after the IMD optimisation has ended for that band. If I CTRL+Q, then power is reset back to zero. If I get back into calibration, power is still zero. If I do calibrate another band (still with 'O') , the calibration succeeds but at the end the PA is not shut down completely.

Now, I think this is hardly enough to put the finals under any substantial strain, if it stays like that for a couple of minutes at most. But I wonder if the few cases of fellows who "left the calibration running and went out for a walk" and then found their finals toast could not be due just to this glitch, i.e., the PA remaining keyed for several minutes, even at lower-than-max power, which might be enough to cook them up, under certain constraints.

Has anyone else noticed this? I guess a consistent set of measures of this effect (if it is not just in my QMX+ specimen) might help Hans pin-pointing the issue when he is back from vacation.

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Hope this helps.

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72/73 de Enzo M0KTZ

Enzo, I checked a couple of IMD optimizations on my QMX, and this does not happen.

Others should check.

Anything else special about your setup or the sequence of test steps you did?
Stan KC7XE

Nothing special Stan. Ran the calibration steps in sequence, one by one, using 'O', '+', 'O', '+', etc. Will run again and measure the power out in the dummy load for each IMD test (so far have only looked at the pwr indicator on the display, showing 1-4 bars at the end of each test, and back to zero bars if I CTRL+Q).

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The unit is a rev 1, assembled by me, works perfectly on all bands otherwise (CW only tested), with out power between 2.8W and 5W at 11.6V.

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72/73 de Enzo M0KTZ

For my test, I was watching the output on an oscilloscope.? It clearly turned off at the end of each test.? ?I didn't even glance at the front panel, so I can't say if the power meter there stuck on a non-zero value.

Stan KC7XE?