QDX Hi Bands Low Output Power #test #gdx


Hi All

Another low power question here. I'm completely stuck here on what to next look at. I have a new hi bands QDX. It all works fine but only outputs 1.5 watts or there abouts across all bands checked on dummy load and 2 power meters. Uses about 330 to 450 mA on transmits. Was built for 9V. I tried it on 12v but didn't go any higher. I played with the toroid windings but didn't do much. Been over the soldering 3 times. Double checked the T1 winding, checked the winding numbers. Checked DC continuity across each of the 47uH axial inductors.
I've looked at the trouble shooting page and done what I can and with my knowledge and only have a simple multimeter. Haven't yet done anything with Terminal.

I'm sure I've spent more time trouble shooting than building it. Although it is making contacts all around the world!

What I'm I missing. I'll happily be wrong :)

Any help greatly appriciated


Al Holt

Do you think there could be any issues with your power supply and/or power connection into the QDX?

It's better to test transmit power output using the terminal application.

Have you tried checking the voltage at the gates of the PA FETs when it's in transmit mode? You have to be very careful to not let your probe slip and short the FET's pins. With a DMM set on DC you should get ~2.5V at each gate during transmit.

Good luck!



Thanks for your info. I since took a winding off the secondary and put 13v in. I did get 3 to 4.2 watts out on most bands. And then tweaking the toroiads, the magic smoke came out!! Transistors now burnt out and possible an IC chip. Forgot I was putting 13.8v in and not 12v!

One step forward, two back! 

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