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Follow up: after turning off QMX and restarting, working fine 005 f/w. -- 73, Dan? NM3A

When I first got my QMX, I made a few FT8 contacts on 40m & 20m with no problems. I have since concentrated on CW. Now that that's working pretty well, I have gone back to FT8. I noticed some weird

John, since the microcontroller can get the PWM voltage down to 0 during transmit, it looks more as if the microcontroller changes the port to an input port for some reason. I attach an image from the

I have just finished restoring a Yaesu FT902DM and some of the soldering on the internal boards looks a lot worse than that. 73s Ted 2E0THH

the QCX+ 10 died during the field day. It was suddenly constantly transmitting.? No Idea what happened but later I noticed? that one line between the Key and the Atmega was having a low resistance.

Oh, I see you have already done that! Your numbers do suggest a failed transistor. JZ

Gunnar, Your observation of 1 volt at the PWM input is strongly suggestive of a gate to drain short in Q501. The resulting current flow into the microcontroller pin could overwhelm its ability to hold

Thank you all for your answers, I will try to answer all your questions in the order received: Peter G3SPL, well I noted that the minimum power consumption occurred at 9.2V. If everything was OK it

Thanks, Hans. Like I said, this is mostly my own personal neurosis since qualitatively the radio is working great... I'm just striving to factor out my "style" and luck as much as humanly possible. I

Well, not just a component? We summer in Maine and when closing up in the fall place the toaster in the microwave to keep critters and dust out. This year I opened the place up myself ahead of my XYL

My Rev 3 is working beautifully with no mods. 73 Dick W4PID

Well, I feel kind of dumb.? I had the power setting set to full power in WSJTX/JTDX, but the output at the system level (through the pulse audio control) was only about 50%.? Setting that to 100%

Tnx QSO, WB4EVH 72, Bill, N4QA

For completeness, check Q501 for shorts as well. JZ

Tnx agn, WB4EVH. 72, Bill, N4QA

Gunnar, one more thing... With power off check the resistance from Q502 gate to drain and gate to source. If a short to gate has developed both Q502 and Q501 will exhibit elevated temperatures. JZ

Good point, John! -- Peter Lee *G3SPL*

Gunnar, It is as if the feedback loop that controls the bias buck converter is not working. Check at both sides of R505 to make sure the ADC is getting a converter output sense signal. Check at the

Peter, That is a good question. But it does seem strange. Assuming that transmit is not attempted I'd expect the current to go down as voltage is increased due to the switched regulators on board. 73

Mine looked like that also. Worked fine without doing anything. -- 73, Dan? NM3A