Hi, Please send link to Hans' descriptions of the circuits. I would like to know how my QMX + works. I don't see the detailed explanation in the shop. Thanks, Merry Christmas George K3GK

The wiki page QMX QMX_plus Audio PCM1804 has been updated by @Ludwig_DH8WN <DH8WN@...>. Compare Revisions

Just received my qmx 20-10 ... really the best Xmas gift ever 😊 thanks Hans and team, wish a very nice Xmas and a happy new year.... vy 73 de Udo DF4BJ

My QMX luck is not too much better on this build than the last one. Well at least this one boots up and it actually transmits great. Got good RBN report. Receive is another story. When I first completed it, I was getting really loud noise from speaker and S-meter shows strong signal that fluctuates with Dummy load attached. Here is what I have done so far. I checked T401 by pulling it out and verifying I didn't have anything crossed. I didn't. I replaced the PCM1804 although that was with the one on the other one that the processor failed so not 100% certain it is good but should be. 9K ohms for VDD and about 50K ohms for VCC to ground. I have attached my hardware test results for 20M as most are about the same for all bands with the areas of concern. The only other two are ADC I Q test as the displays are different but then again similar and RF Sweep. Any other troubleshooting suggestions would be greatly appreciated. I do have a scope, signal gen and a TinySA if any of those can aid. thanks and 73 Bob WV7W

Is the QMX itself in any way capable to negotiate the required voltage with the power bank PD? In other words is a 12V trigger cable required or not? I feel more comfy with a trigger cable as it steers away from any negotiating. 73 es dx

I killed my QDX running off of a fully charged lifepo4. Reached out to Jeff and now I have a working QDX again. Awesome work Jeff. thanks -- 73s, AA6ST Sameer

Building my QCX Mini and came to this step over an hour ago! Lol I’ve searched until I’m blue in the face…. Closest I could find was a builder’s note for Rev2 PCB, to orient striped end of the body of D33 in the hole closest to the edge of the PCB. Is that correct for Rev3 also? Thanks, Brent

Wow. Thanks to everyone who's trying to help. I really appreciate it. In response to the suggestions/questions: To Ronald Taylor (did I try a USB cable with chokes on both ends?): Yes. Two different cables with chokes. No effect. To Alan G4ZFQ (is the mic enabled inn security/privacy settings?): Yes. Both the general "allow apps to access mic" is "ON" and the "allow desktop apps to access mic" is "ON; and the latter shows WSJT-X, and when I boot that program, the "allow mic" page shows WSJT-X "in use." To Bruce KG8IW (is QMX otherwise working OK, can I hear FT8 signal in headphone?): Yes. I hear the FT8 distinctive tones quite clearly. To Gerald H. (is the clock out of sync?): I don't think so. I run Dimension 4 in background and I checked the last sync and it was only off by 0.042 sec. To Paul AI7JR (is the QMX set to IQ mode?): No. IQ mode shows "DISABLE" In short, while all of those were great suggestions, it doesn't look like we've zeroed in on the issue yet. But here's a weirdness. When I first started the QMX this morning to follow up on the above leads, it worked fine! The waterfall on my PC was the usual FT8 waterfall, signals were decoding fine, and the QMX seemed to transmit. All of the 40m FT8 signals were weak so I figured I'd switch to 20m where my QRP transmit levels might fare better, and the stupid *$%#&$* QMX quit working again ... back to the same waterfall shown below. I tried stopping and restarting the QMX, restarting the laptop, removing and reinserting the USB cable, jiggling the antenna, etc. etc., but nothing got me back to WSJT working. Now I'm doubly stumped. Anything else I can try? Failing a fix, I'm wondering if I should send it back to qrp-labs for a check/repair? Thanks again to everyone, 73 Skip K4EAK P.S. I think I accidentally deleted the original thread trying to do an edit. Oops. :)

GM everyone, I was able to complete the kit and make confirmed QSOs on most bands and modes. At one point, the unit seemed to be unable to switch on at all. Nothing on the display. I checked the battery, power cable, 12V socket, there is voltage in V-IN everywhere, even at the switch-on button. There does not seem to be any short between ground nor V-IN, Vcc nor Vdd. The only thing i can see is that i had overcharged my battery to 13V or so. I would think that this could affect the PA but probably not the display or CPU. What would you suggest i check, do i need another display or unit ? Many thanks, Sly Coulombe VA2YZX

Hi I am looking at the WTS transformer instructions, and notice that the wires on the non-tapped side of the primary seem to be crossed. Is this intentional or a trick of the light. I don’t think circuit wise it makes any difference but thought I ought to check. 73 and season’s greetings Stewart/G3YSX

Hi all, I just finished up my QMX+ build and I ran it through the diagnostics. I see that the rig is putting out 5.7 watts on 160 m and 5.2 watts on 80 m. All the other bands show less than 5 watts. Do I need to be concerned with the higher power output on 160 and 80 m ? I will run this radio for cw and have no plans for the digital modes. Thanks for any suggestion, Doug. KF8VS

Anyone using this setup to interact via a USB to serial port converter with logbook or contest logging such as N1MM+ to control frequency, mode etc of the QMX. If so, are you using Macports or something different to recognize the serial connection. TIA, and Merry Christmas! Joe K8FC

Finished building QMX+. All seems well except that when pressing the encoder to shut down. I get the Shut Down Msg, it goes away, but the LCD still stays lit. Once that happens the encoder no longer functions. If I remove the dc power and plug it back in all is well until I try to shut down again. I am receiving and sending ft8 with no issues. According to Putty screen anywhere between 3.2 and 4.2 watts on all bands. PSK Reporter shows being heard all over the US and Europe. I have researched the Groups post, but no real solutions. I have inspected solder joints, removed and inspected both sides of the 5V and 3 volt SMPS. I do not have an oscilloscope but do have DVM. Any thoughts? Thanks, Scott - K1SMK Liverpool, NY USA

While working on another problem I had a strange issue with bad QRM coming through the radio. I tried a number of things, swapping around coax, adjusting location of things, but couldn't supress it. Then I noticed that my SWR was oscillating between 1 & 2....; running an SWR sweep confirmed the strange behaviour. A power off/on didn't sort it, and switching band didn't seem to make much difference. Eventually, on a whim, I did a factory reset..... and it was gone! Has anyone seen this behavior? A software gremlin? Or a hardware issue with my build? Later, I noticed that doing an audio filter sweep leaves the radio making a lot more noise, which a power-off will sort. I'm hoping these are just firmware/bugs! In operation the radio seems to be operating perfectly....

Good morning, I am hoping the knowledge folks here will be able to assist me getting my new pre-assembled 12v QMX (60-15) working. I received the radio two days ago and everything checked out. I am using a talencell which is not fully charged (outputting around 11.7v) and this morning I was using it in practice mode to work on CW sending practice and the screen went blank. It stayed backlit and I could still hear white noise and the CW side tone when keying the paddles but no text. It connects to the PC and I can run menus in the terminal just fine. It did at one point have the text come back for 45 seconds but then it disappeared again. So far I have done a factory reset and checked that it can go into firmware update mode, but no luck. I have not opened it up and could probably check some basics internally if that's needed. Any assistance would be greatly appreciated to get my Christmas present up and running. Thanks, Josh KC3ZJW