QDX blown...again

Last night, I tried my hand at some FT8 with the new QDX. I called CQ a few times and got a reply. Just as I finished the first QSO, the QDX died and my power supply was showing a short.

I opened up the case and could smell the magic smoke. I couldn’t see any obvious cause, but I figured it would be one of the output transistors since I’ve already had to replace them once.

I desoldered all four of them and tested them.

The first three tested fine.

The last one I tested showed as two resistors.

I replaced the bad BS170 and got the QDX back on the air.