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OK Giovanni! Don't give up! This QMX can be restored. JZ wrote:

I will check it

Many thank's..... i think use qmx only as receiver....

Giovanna, I think the arrow you have drawn on your photo indicates a connection between BS170 transistor drains and ground, if I am reading the PCB layout correctly. That would not be a good

I forgot to say… clean up the Q507 pad after removal. ?Clean off leg pieces and all solder. ?Then apply fresh flux before soldering in a new one. Jeff W1NC

Thank you, Jeff! Good Luck, Giovanni! BTW, I am looking at your photo and also studying Hans' layout to see what you are flagging. Do I see a subtle BS170 gate to drain short in your

Hello Giovanni, John alerted me to your post. the safest way to remove Q507 is to first carefully remove the inductor L502. ?That should be easy with flux, solder wick and a decent iron. ?Then cut

I remind a short cut there

Ouch! That looks pretty bad, Giovanni! That transistor is a pretty robust device. Whatever killed it must have been an energetic event. Carefully inspect around the PA circuitry and make sure there

Gate and l502 are far away

Gate source 0.6 ohm, source gate 0.6 ohm, gate drain 0.8 ohm, drain gate 0.8, source drain 0.3 ohm? drain source 0.3

G., One more thing... If a short (e.g. solder bridge) exists between gate and L502, as was the case prior, it will read as a hard short gate-to-drain at Q507. You should check that as well before

Giovanni, Before you attempt removal, please post what readings you obtained. Remember, there are other circuit elements present that must be considered. JZ wrote:

Yes! Q507 shorted! Measured drain and source and also shorted with gate! Vy difficult desolder! I have not hot air desolder, is there a fast solution?

I agree with your approach regarding the input and output impedance measurements. During the construction and measurements, I must admit that this 10W PA is a well-thought-out design Wel done

Good catch, Timo. That explains a lot. JZ

Hi Gary, thanks for posting that - I second your findings. I had posted a description in the "ALPHA 1_00_015" topic [1] together with some other thoughts, where Adrian YO3GFH's answer led me to

Dan, There would not be enough voltage to run the QDX if you put 5 volts to the power socket. I see no reason that it would be damaged, just not work. It is possible that with a slight mod to the

Low power on all high band about 1-2 watts, kit 12v, tks for answer, i will check what you tell me. Tks, i will inform you next. 73 de it9xjj

I am using it on a Panasonic Toughbook, USB 3.0 and probably higher current rating than a standard USB 3.0 port, but I have been unable to find a specification for the current on those ports. I see no