(tr)uSDX works on usb power but not DC

[kd2]

Initially I powered my radio through the DC power connector using a USB-C battery pack and voltage regulator. Later I connected my (tr) uSDX to an antenna and was able to receive using the micro-USB power. At one point my screen suddenly dimmed, I do not know why, but I could still receive, so I assumed nothing was damaged. Now I can no longer power my radio through the barrel connector, but still can power it through the usb. I got the kit pre-assembled, and mostly kept the radio in practice mode. Does anyone know what might have caused this issue and how to fix it or troubleshoot further?

73

[kd2]

I just had another thought. Is it possible that I overdrove the radio by receiving too strong a signal. The antenna I used is part of my club’s station and could another transmission damaged my radio? If so is this fixable?

[VE3RRD]

What voltage were you applying through the DC power connector? The minimum voltage is 7 VDC when applied there.

[kd2]

I was powering it with 9V to be safe, and I just tried using a lab power supply at 13 V and it draws over 500mA without turning on. This leads me to believe it’s a short somewhere inside and my own power supply has a current limiter.

[s57l]

Burnt finals? Remove the rf board and try without it.
Maybe also some choke/polyfuse died of excessive current and now only works on microusb?

[kd2]

Thank you for the suggestion! The main board works from the barrel jack if I disconnect the RF board. I do not know how to proceed from here though.

[s57l]

This looks like burned finals. You never stated which band options you have, what output fets.
Unusual, if you did not transmit with bad/without antenna?
As they are very cheap i would take them off (solder and wire cutters, depends) and try again with rf board installed. To replace fets you need new ones (from reputable seller, there are many fakes outthere!) and strong and hot soldering iron and some skill to do it.
Easy to bo, but i have soldering iron sitting on my bench and fets in my drawer…
Hope it helps?
73

[Pascal]

Hi Kd2

Could you resolve the problem, finaly only the finals?
I have the same problem.

vy 73 Pascal

[Pascal]

hi

Changed the transistors this afternoon, everything is OK.

vy 73, Pascal

[kd2]

Because I purchased through amazon, it was easier to have the radio replaced than risk further damaging something myself.

Glad you were able to find a solution!

73