Re: First HF radio..incensed a week ago...I think I blew up my uBitXv4.

Evan Hand

My first thought is to check the mic and key connections.  I have had similar issues with 3.5mm plugs that being pushed in all the way.  One of my key paddles has that issue, and I must constantly check that it is pushed in all the way.

I would verify the operation of the key input.  That is the line that needs the 4.7kohm resistor.  Check with a voltmeter after connecting a dummy load, or disconnecting the power to the power amp finals (the middle connector, brown wire, on the 3 pin header on the main board).

Did you by chance get one of the AmatuerRadioKits cases?  If so, I would verify the soldering on the front PCB, making sure that all of the 3.5mm jacks are soldered correctly, and no shorts.  You will also need another 3 pin header plug to separate the PA power, as the instructions for that case has you connect them together at the back PCB.

In any case, I think that you have a wiring issue that you need to resolve.  With the situation that you describe, even a short blip on the transmit key can cause the Nano to lock up due to RF feedback when you do not have a matched load.  Before breaking out the scope, I would attach a dummy load and verify that it operates properly. 

A good 20 watt low-cost dummy load can be ordered from QRP-Labs for $8.50 plus shippling.  Alternates can be had from Amazon, though without the power breakout circuit.

Hope this helps.

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