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Lee;Wow - that 3.6 Volt Zener should not have seen an overstress condition sitting on the 3.3 Volt VDD bus - unless the switching regulator did something it shouldn't have.Looking forward to hearing

By the way, I will accept the possibility that the meter might need calibration! It's literally brand new, out of the box, and it's a cross-needle type with what look to be calibration screws under

A couple of weeks ago, I think, I brought up an issue I'd seen with my QMX low-band (20-80), where I was only getting about 1.2W out on 20 meters. Today, I decided to run some tests using a new power

This subject seemed exhaustive. After reading all the points made, I've almost decided on three best practices to use for winding a toroid: - Wind a larger toroid with a small vise. - Wind a small

I can not get the USB to be recognized . Hope the MCU is not dead.

Another possibly "obvious" question -- the screen doesn't come up, but does the terminal app? There's an awful lot of diagnostic available IF you can get to the terminal app.

I did exactly the same thing. Running it for a few hours. I tilted the rig up to get a better view of the screen and heard a crackle.? Then it shut down and will not power up. Checked the dc plug?

Steve, Thanks for the info.? I checked the ground to vcc and showed 330 ohms.? found D109 Zener Diode exploded.on one end. I did get a voltage reading of 2.1 volts. on it though. I removed D109?

Thanks both - yes, it’s out of the case - no shorts or problems around the power socket. The issue is the same out of the case. The plug is actually a good fit so I’m not sure why it happened.

Hi Steve;Can you slide the board out of the case and then check to see if the short is still present?73, Steve, N3SB?

Any of the small chisel tips seems best for me. I find the the very pointed ones do not supply enough heat over a wide area. But if you're working on tiny IC legs then use them, otherwise chisel tips

At the risk of being suuuuuper obvious, I'd check that 12V connector that wiggled when you leaned over! If it were me, my first thought would be to wonder if one if the solder joints on the 12V

After successfully building and tuning my QMX+ (V2 PCB), after a day's use I've done it again and blown something up! I managed to accidentally 'wiggle' the 12V connector with the radio on while

I am about to start on a QDX, followed closely by a QMX, then a QMX+. I have a Circuit Specialists 60W adjustable temp iron (similar to a Hakko) and a variety of tips to choose from. What have you

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