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Windows 10 often does that if you have the QMX on when you plug in the usb cable. Try turning it off and then plug in the USB cable. Wait a bit for Windows to get it's act together the power on the

Nuvistors are interesting!? I had two of them in a 2 meter rx preamp back in the late 60's.? The tubes are still available, the sockets not so much.? Least expensive 5 pin socket I found just now

Andy, Sounds good, but we already had one failure reported switching from 6 to 12V instantaneously. I'd rather rather stick with my 4SQRP tuner. No finals failures yet on 7 QRP Labs rigs in 5 years.

Lee, one point of clarification: The QCX is class E, the QDX and QMX are class D. ?All are relying on digital type of response from the finals. 73 Evan AC9TU

If you can install firmware and reinstall firmware then it is was acting as a USB device. The ONLY time the QMX will act as a USB device is during installation of firmware and that seems to work fine

watch for the topic: Part 3: Good & Bad QRP Class E Devices Or “Bigger is not Better ” or "Why the IRF510 Makes a Good 5w Class C PA? ? ?&? ? ?Why the 2N7000 makes a good QRP Class E final

Hello everyone. I’ve been trying to get my QMX To come up as a USB device on my computer. it comes up with the message that I copied off my screen that I attached to this post. (USB device not

I built a QMX about 3 weeks ago. I had a short on the 5 volt PS board and had to wait for a replacement. QRP-Labs was very fast with a replacement. I just don’t have the equipment to do surface

I was able to obtain a Mirage MP1 which was checked against a accurate station monitor. From 2.5 watts to 1000 watts it was dead on, the swr was slightly off, very slightly. This is not the current

Mario, I'd wondered what that thing did. Fitted one to a probe and plugged it into a T-connector that I just received and I was good to go! Thanks for the tip! (no pun intended ;-)) ------- To

I'm currently running my QMX on two linear regulators, a L7805CV for the 5V and a LD33CV for the 3.3V, both TO-220.? This is built onto a small veroboard which just about fits.? I don't have power

Hi Hans et al, My QMX is working fine. Leave it as it is then? Hmmm, as I see supplying the MC from 3V3 SMPS controlled by MC too risky (although it works well, I have to admit!!!) I want to try

I am quite puzzled with these changes of finals to IRF510s and conceivably to RF bipolars. If you make this change, it seems to me that you are no longer really running this in Class E due to the

OK, I've been tempted to mute every thread about those MOSFETs, because I'm not feeling they're as critical an issue as many others evidently do.? If the horse isn't dead from the beating it's taken,

Yup, dead MCU . Sad, sorry...JZ

John, Evan: Great that you have a spice model. From your spice modeling are you able to give an opinion on acceptable, allowable steady state SWR since it is rare to get a perfect match. Hans may also

Nuvistors? I have a box of new never used Nuvistors. Around here someplace. Dave

In response to Hans' message of a few days ago: In my case, IC101 does not get any voltage from the drain of Q102 so never produces 3.3V to supply the STM32F446. The question is why does it not get

Hi all, I have done some measurements using a QDX-LowBands, 50W QCX PA and ATU-100 upgraded for QRP. It is not the measurement of voltage at MOSFET's drain as we all are curious about but rather at

Very interesting mods. Has anybody considered using?RD16HHF1 would it make sense?