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Thank you Sverre,?? I went to the link you provided and saw and read what I think I need to do.? Hope I can work you when I get my QDX's finished and tested. Take care and have fun. 73 Dave

Dear Sverre, Thank you for your explanation and you website that did a really good job of telling me what I wanted to know.? I will go find me some 47V Zenner diodes. Take care and have fun. I hope

Gary, I totally agree with your comments using a TVS. That’s the right way to do it. Zener is a poorman’s junk box solution. Zeners can be found in junkbox, at least in my case and TVS are more

Has any of the boards ever failed with the unable to shutdown symptom after a few minutes of normal operation? Initial investigation D101 seem to have failed short. My kit also had q103/q104 short.

Chris, I think I will go for BPF bypass straight away. In this way I will confirm that this is were problem lies. I located T401 input connection but I need to confirm <RX_IN> side. Do you mean

Don, The audio amplifier for the headphone jack is IC404. You should check it for proper bias voltages. I didn't see if you wired the radio for 9v or 12v, but you should find a little less than half

Transient Voltage Suppression (TVS) devices are more appropriate protectors than Zeners. They are designed to absorb overvoltage transients and react faster than Zeners which are designed to operate

Hi Evan Yes that could be a possibility too. Doing it on the supply rail isn't because there's a capacitor on the potential divider which slows everything down too much. Yes perhaps a fast loop could

Hi all I agree a series resistor would prevent the GPIO conflict. The GPIO pin is necessarily configured as push-pull. A series resistor would reduce the efficiency of the buck converter. However my

Hi all, I have had a QDX for a few years. I built it and made it for 9 volts. It has done a great job with over 500 grids worked. In the past I might have made 20 contacts in a day but recently that

I overheated my headphone jack on the initial assembly. I swapped it with the PTT jack to get up and running. It's not uncommon, these little jacks can't handle much heat.

Hans, Is it possible to set an interrupt routine based on time to sample the 5-volt input and shut down the output when it reaches a threshold value greater than 5 volts but less than the 5.6-volt

Hello Hans, first of all, I am not the inventor of this solution, but I think it is a good one. I'll try to answer your questions : 1) No, I have not tried it and I am reluctant to put my QMX to the

My first impression was "What a neat hack!" but there are a few unanswered issues besides the ones Hans brings up: Did you change D108 to a 5V zener? Which one? What's the reverse leakage current

Hans, The proposed circuit has problems but the concept shows promise. I didn't look at it very carefully. I saw the issue of " the transistor will be shorting the processor's GPIO pin directly to

These can also be found for around the same price on eBay sold by rapidonline. Free postage too.

Hi Gunnar, all A few comments/questions... 1) this circuit has been proposed, but has anyone actually tried it for real, and then verified that on the step change from 6V to 12V it does protect the

Billy, et al, If you are going to continue building kits like this you definitely need this: Optivisor Binocular Magnifier micromark.com There are cheaper versions elsewhere. I kept my two units when

Chris and Mike Thank you for your input, it is much appreciated. Today propagation is s**t so good time for tinkering with radio gear. I will report later on

possibly either a duff jack socket or duff phones..