I'm sure this isn't new, but just to talk about my experience. My QMX has been working - Tx and Rx, but I hadn't used it for some time apart from some listening and testing of a mini antenna tuner. Today, there was no Tx o/p on any band and the hardware tests showed the same on pressing 'T' with a dummy load. I took the QMX out of its case and measured around the PA transistors, assuming there had been a catastrophic failure. The PA showed the correct drain volts, so nothing was short circuit. However there was no drive, which I traced to no Tx signal from the microprocessor on pin 2 etc of IC503, so the driver chip wasn't enabled. It didn't matter whether SWR protection was enabled or not. In desperation, I performed a factory reset, and this re-enabled Tx, so the microprocessor was happy and working again. Now I have to work out what settings I had tweaked, as my settings are now gone.
The processor seems a bit too sensitive to this sort of failure mode.
?
73
Tony G3OVH
