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Hi all, Yesterday, I finally found the time to finish building my second QMX (Rev.2, 10m - 20m). Initial setup was easy, and after loading the latest firmware, all tests ran smoothly. Today was its first use, which was also successful with a few FT8 QSOs. But after about 3 hours, the QMX said goodbye with a loud pop. C107 looked like the picture below: https://www.bitquell.de/nextcloud/index.php/s/cf9tbs844aW2mgq I can't identify a cause for this defect. The QMX is built for 9V and was powered by the stabilized 9V output of a TelentCell LF4100. The antenna was a precisely tuned vertical. Will replacing C107 be enough? I'm worried about Q107. Could the burn that can be seen in the picture have been caused by C107, or is Q107 also defective? 73, Joerg DG0JDE

Do any of the commercially available hand microphones for existing QRP radios work with the new QMX SSB? Or perhaps pre-wired adapters for those mics already in the marketplace? Bill W3WJ

I just upgraded to the 027 firmware on my QMX, from 018. Being able to select the CW filter is very nice, but I don't understand how to enable cascading or compounding of two CW filters. The manual says there are two CW filters - 300 and 500 Hz, yet the submenu shows 8 filters, ranging from 50 Hz to 500 Hz. Thanks and 73, Steve, N2IC

Hello! I am trying to find right settings to start work with WinLink and VARA HF threw QMX. CAT connection is OK. The only problem here is that when I choose some Gateway channel QMX always switches to USB mode from DiGi. But it is not a big deal to return back to DiGi manually. The main problem is that when I start connection with the chosen channel QMX shows two dots as TX status. Which means that audio level from PC is too low. But I've put it to maximum. And everything works fine with WSJT-X and JS8Call. So problem is definitely with some WinLink VARA HF settings? Can smb help? Hans, did you try to use WinLink with QMX?

My QMX is working perfect with 12V, but I would like to try 9V to reduce power on FT8. By lowering voltage with a regulated power supply, qmx is going off at <10V (qmx seems not to be completely off, but there is no audio and no display). By increasing voltage again, QMX is starting again at >10V (without pressing "On/Off knob). At exactly 10V QMX is alternately going on and off. The minimal voltage in protection settings is 7V, why isn't it working with 9V? Vy 73 and thanks in advance, Stojan, DK4SR

On 4/21/25 I had a CW practice / rag chew session on 20 meters. I worked no stations: Conditions were OK. SSN = 108, SFI = 156, A = 14, K = 5. I heard several very weak stations calling but they were too weak to work. My next CW practice session will be April 23 at 16:00 EDT / 20:00 UTC on 20 meters. Anyone and everyone is welcome. This practice is intended for operators who are new to CW or they need some practice. IT DOES NOT MATTER HOW POOR YOUR CW IS. Mistakes are OK. Poor fists are OK. Slow speed is OK. Really slow speed is OK. This practice is meant for you to improve your CW. I will do my best to adjust to your skill level. Operate at any power level. If several stations show up, I will operate as a round-table control station. I will do it as a round-table so everyone gets a chance to transmit. Please listen to my directions. Details: Date - April 23 2025 Time - 16:00 EDT 20:00 UTC Band - 20 Meters How to find me - I will find a clear frequency and call CQ. Go to the Reverse Beacon Network and search for my call sign AB8DF. That will tell you what frequency I am on. Tune your station to that frequency and if you hear me give me a call. If there is a QSO in progress, please wait for a break in the action. Then send your callsign. If I hear you, I will invite you to join the QSO and start a round-table QSO. Reply to this email if you have questions. IT DOES NOT MATTER HOW POOR CW IS Ed AB8DF

I finished assembling my QMX+ (including a battery mod) and finally got the chance to test it. In the diagnostics everything appears to check out, until I press P. At that point the SMPS bias current for every band is ~4.6mA (where the PIN forward bias is 30mA). If I press T (while connected to a dummy load), the RF output and the Transmitter Voltage turn RED, with the Voltage reporting ~9.5-10.0V. Power is consistently listed as 0.0W, and the SWR (into the 50 Ohm dummy load) is all over the map. Any ideas what I did wrong? I've looked at all of my soldering connections multiple times and don't see any bad joints or bridges. I've checked everywhere I can think of for continuity, and everything has checked out so far.

Hello, I recently just fished putting my QMX Rev 4 kit together with the windings necessary for 12v input. As I was going along I verified I all continuity checks as instructed and verified no pads were bridged. Upon attempting to power on the device, I connected my 12v power supply to the barrel connector. The screen immediately lit up and I had black rectangles across the top half of the screen. A second or two later I started seeing smoke, heard a pop, and the screen went dark. Upon further inspection, I was able to discern that the Q108 MOSFET on Plug-in PCB #1 blistered and exploded. The L101 inductor nearby also looks a little singed but the enamel coating does not appear to be compromised. I do not see any other areas of the device that appear to have been compromised or damaged. I was wondering if anyone may be able to assist with what actually went wrong here. I have ordered a new power supply board as well as a replacement MOSFET to try my hand and replacing the bad component. My current theories on what went wrong are: I am missing a bad solder joint somewhere that caused the issue, still attempting to find one if so. It's still unclear why the MOSFET would blow in this case as it's rated for 20V and my power supply used is only capable of 12V out. MOSFET AO0415A Data Sheet There is a step in the instructions that says to bend a tab of the LCD screen at about 45 degrees to clear the L101 inductor. I noticed that this appears to have been discolored possibly due to heat. There's a good chance that this tab was not bent quite enough and made contact with the top face of the L101 inductor, though I don't think the top face is conductive. This could have resulted in a short to ground? My winding on the RWTST Transformer is somehow incorrect. Image upon powering up. Seconds before smoke and pop. Note: I did not press the left dial in, the screen lit up as soon as power was supplied to the barrel connector.

Hello, I completed building the QMX yesterday. The initial plug in went smooth, no smoke no current draw. I booted the QMX into update mode, put the firmware on it no problems at all. Then I removed and re-inserted the dc plug and tried to start the radio by pressing the left encoder, suddenly I saw big current draw (stupidly i forgot to limit my power supply) it went up to something like 7 amps, so I unplugged it immediately. I dint see any smoke but the device did get hot in some areas. Visually I do not see anything burned on any of the PCB. So now, when I plug the radio in the DC plug nothing happens until I press the left encoder which creates a short and puts the power supply into constant current mode. (This time limited...) Can anyone please advise for any troubleshooting steps? I put some pictures of the boards in attachment. Thank you.