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Hi Lee;D103 provides 3.3 Volts from IC101 to the VDD bus. IC101 has been configured to provide about 3.9 Volts (what you measured) so that after the 0.6 Volt drop across D103, 3.3 Volts is available

Hello All,, I am troubleshooting a dead QMX +.It worked for a few hours and then it died and will not turn on.. Pressing the on button , I see about 23 ma/ draw. let it off and 0 ma. I HAVE A NEWER

Hi Sardar;This test was a good idea - it will help to pinpoint the short.You could try lifting both leads of Q108 (leave its tab soldered in place) then reconnect U101 and see if the current draw is

Stan, I have utilized the Vcc (5V) rail only. Nothing was powered on from the 3.3V rail of the QMX+. Let's see what further measurements show. -- 73, Sardar ( AC8L).

I've had windy conditions give me a variable SWR, depending on how the antenna was hung. But when SWR really started hassling me, I fixed it by using a different feedline. Later I diagnosed a flaky

Yes, I meant tuning range, sorry. A little more background.? Fifteen years ago I built a 40m SSB receiver from a Softrock, analog I/O, and DSP written in VHDL on a Spartan-3 FPGA.? That was my

Good catch on the 9:1 issue, Michael. Thinking of some potentially field expedient solutions: If you have tuner with you, perhaps treat it like a “random” wire with the 9:1 unun. If no tuner,

To find the COM ports https://www.hamcrafters2.com/WKscan.html is a helpful little software even if you don't use a Winkeyer -- Martin DK3UW

I just repaired a QMX+ that, when on two different known good dummy loads, it tripped on SWR protection on some bands and not others. The problem was some remaining enamel on a couple of the wires on

If I were in your shoes I would leave the SWR protection enabled. 3:1 is a reasonable threshold. Maybe you could double check your antenna and coax performance by using the ‘Hardware Test’ >

An end-fed half wave needs a 49:1 transformer, not a 9:1! So that's probably not helping you any! 9:1 is used with end-fed random wires. However, assuming for the moment that was a typo, the main

I’m traveling in GB and attempting to activate several POTA parks while I’m here. ?I’m away from my test equipment and I’m soliciting advice. I took my QMX low band and a 20m QCX for backup.

I fell over this a few minutes ago: https://www.youtube.com/watch?v=GzdamEdZUEg The description points to the blog of jp3dgt: https://jp3dgt.blog.fc2.com/blog-entry-868.html in japanese but google

Thanks very much Dave I have reset, and gone into the menu. Can change bands now; ok. Now low out put on all bands ?- between 1.5 to 2.5 w across bands. I’ll try diagnostics if I can get it wired

Interesting measurements. In your second post that updated the statement of the failure, you said that you had the external device connected to Vcc (5V), not Vdd (3.3V).? Is that correct? Or was it

Colour coding has saved me from a senior's moment or three ?

4. Always use the 'tune SWR' feature of the QMX while tuning (menu -> hardware tests -> tune swr).? This is less convenient than just keying, but reduces the output power while tuning to 25% by

Hi Dan Re band selection, check out section 5.17 in QMX operation manual: "System config This menu contains several system configuration parameters which don’t seem to belong in any other menu.

I love the green!

Good catch. It should read "15 turn tap" to correspond with the photos. I wound my L405a with green magnet wire. https://www.qsl.net/v/va3rr//NC40/myL405ab.jpg GL de va3rr