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Hello all, Last week I finished the build of a rev1 QMX+. No problems were encountered and it worked fine on powering up. During the build, I have measured the frequency response of the low pass filters.These appeared to agree very well with a simulation carried out with help of RFsim99. One anomaly was encountered: the series resonance of L507, a RFC feeding DC to the centre of the 60M-80M low pass filter caused an additional loss of about 0.5 dB just in the 60M band. To get rid of it the Q of the RFC was lowered by mounting a 2K2 SMD resistor in parallel of L507. I have been reading that many builders experienced a drop in output power on the higher bands and my build was no exception. As I like tinkering a lot, this appeared to be a nice challenge to see if this 'issue' could be improved upon. My build is for a supply voltage of 9V. Reading up on this issue on this list, it appears that the output transformer L501 is critical. Muhsin, TA1MHS, wrote that he had replaced the BN43-202 binocular core with a BN-61-202 core, which improved performance on the higher bands. Apparently a lower inductance for L501 helps. I did not have stock of a BN-61-202 core, but I had a BN-43-302 at hand and wound a WTST on it for 9V operation. The change in output power was negligible, though. The next thing I tried was using 2 x 3 BS170 instead of 2 x 2. Powered with 10V, gave these results: Band PWR-W I-mA 160 6.55 1150 80 5.35 928 60 4.99 925 40 5.73 975 30 5.68 1363 20 4.86 931 17 3.57 1258 15 5.73 1613 12 3.89 1553 10 5.05 1282 6 3.87 1080 This more or less solves this issue for me, though I don't think this is recommended in actual operating. I wonder what the reason is for the much higher current consumption on e.g. 15M compared to 80M, whilst delivering about the same power? A matter of lower impedance? Anyway, this is great fun. To be continued. Test gear: Sensor Monitor Power Meter 100W dummy-load Rigol DSA-815-TG spectrum analyzer Lab power supply 0-32V 2A 73, Roelof, pa0rdt -- Roelof Bakker, pa0rdt

Stan, Ludwig, Dan, Jeff and all the others, whose names I cannot remember at this moment, for all your time and effort in volunteering to help others... And of course Hans, for designing and providing such an excellent product at such low cost. You are all invaluable gems that give us hope in this rotten world. 73! de Bekir TA2RX

Hi https://github.com/danleetw/FT8TW https://github.com/danleetw/FT8TW/releases 73 DE muhsin TA1MHS

A new chat has been created: Is it possible while my order is not shipped (assembled QMX+): to order dummy load and no to pay for delivering it with QMX+ together? By: Algis Unknown <wiseacre1@...> View/Join This Chat Do not reply to this message to post to the chat. You can participate in chats only through the group's website.

Gents, Just finished build of QMX+. Everything works perfectly from first power-up. Glad I watched Hans' video. The 6-layer board really does take a lot of heat to solder properly. Power is a little low - about 3W on most bands, compared to 4W from my QMX but that doesn't make much difference. One feature would be handy... I find that the QMX goes into SWR protection before my ATU10 has a chance to tune. I have to manually turn off protection when I want to tune a new antenna and/or band. How about when turning keyer speed to zero, in addition to going to straight key, set power to 50% and turn off SWR protection. 73, Glen W6GJB

I am using a GPS QLG2 to supply 1 second pulses to a progrock, the progrock is generating 27Mhz for a AD4351 DDS and 24Mhz for a receive function. On both the signals generated there is a "blip" when the 1pps fires, I have removed the bright green external LED I am using to no avail, also there is no modulating pulse if the GPS is not locked. This may be an old problem, any help appreciated 73 Dave

I just got back from the Pacific NW robotics district championships where N7BIN and team were competing. There are a couple parks just off the highway near Spokane so took time for POTA on the way to/from. I noticed a couple strange things with the 1_01_003 firmware on my QMX rev 2. At one point, after powering down to swap cables, the display showed USB mode but the rig was clearly in LSB mode. I switched to LSB on 20m and everything sounded normal again. It appears that there is some way for the displayed mode and actual mode to get out of sync. When in SSB mode, I noticed that the SWR meter was swinging wildly into territory where SWR protection should have tripped, but SWR protection did not trip. When in CW mode, it behaved as expected. This was transmitting through a ZM-2 tuner adjusted for 1:1 SWR. Despite this, and the challenge of 5W SSB with a low antenna, the activations were still a lot of fun. 73, Mike KK7ER

On p25 of the Rev 3 QMX+ manual, there is a check for continuity to ground from three points A. BEFORE installing T501, when checking the three points A, I get about 15 ohms with the DMM black lead on the ground connection, but open circuit (desired) with the leads reversed (ie red lead on the ground connection). Is this to be expected? The 4 BS170's ARE installed. I am troubleshooting a continuity check problem identified after having installed T501 (now removed). Thanks Steve AK0M

A new chat has been created: I have been enjoying the 10-20m QMX for several weeks. I used two 1N4001 diodes to drop the voltage to about 10.5V. I had a beacon set on 10m. Antenna SWR was 1.2. Everything worked great until today. The diodes melted and the QMX is dead. I took the unit out of the case but there was no visible damage. HELP! By: w8mv@... View/Join This Chat Do not reply to this message to post to the chat. You can participate in chats only through the group's website.

Factory built 12 volts, works perfectly. I've only made a few hundred CW QSOs. -27 firmware installed. With case $165 plus postage from Japan. JS6TMW

My QMX+ went together really nicely, along with my battery and speaker mods. However, the bias current is varying wildly on TX, also transmitter voltage is indicating low and output power varies. All other tests and sweeps look ok. I've attached a short video showing the diagnostics test on TX. I've replaced C504 as has been suggested and reflowed all joints that looked like they might be dry. I'm a bit stuck now on what the issue might be - any thoughts from the hive mind?

A new chat has been created: Hello, i'm sorry for asking newbie-easy questions. Do i need dummy load, perform any possible calibrations if will receive already assembled and tested QMX+? Can i use built in SWR sweep and meter for tuning my antenna? I'll use it mostly for digimodes. By: Algis Unknown <wiseacre1@...> View/Join This Chat Do not reply to this message to post to the chat. You can participate in chats only through the group's website.

Hi, I have released a version 2 of ABS solution. Please refer to the readme front page file at the git repository for full details and release notes: https://github.com/AC8L/QMX_Plus_Autotuner_Internal_Battery_Speaker/ The release includes new PCB fabrication files, BOM and detailed build instructions. This release took into consideration lessons learned and a feedback from first group buy participants fearlessly organized by Cal (AD8Q) and Stan (KC7XE). -- 73, Sardar (AC8L, 4K6SA, VA3DUA).

Well the QMX masterpiece has pulled off the greatest miles per watt of my life, using my homebrew EFHW. I am still is awe to put it mildly. I worked FR8UA at greyline from Montana for a distance of 10,583 miles on FT8. Thank you Hans for all your hard work on this radio, it's truly amazing! John

Hi all I have updated the assembled kits page https://qrp-labs.com/qcxmini/assembled.html In March 2025 we shipped 280 assembled transceiver orders (some containing more than one transceiver). This is a record high number. The waiting time for assembled transceiver orders is currently around 1 month. 73 Hans G0UPL http://qrp-labs.com https://www.buymeacoffee.com/g0upl

When I finished my QMX rev 4, 12v build, it would not mount as a USB drive. I received several thoughtful and helpful suggestions from the community here. Thank you. I followed the suggestions as best I could. In one of the suggestions, Jeffrey Moore, W1NC, was suggested as the go to guy when all else fails. I sent my unit to Jeff and in my experience he is, indeed, the go to guy when you have exhausted your own experience. He fixed my unit and tested it on all bands. He provided me a detailed list of all that he did to fix the unit. In short, he is thorough. He provided such a thorough list of my defects in construction that convinced me I should have ordered a factory constructed unit. LOL If you, like me, have screwed something up beyond your ability to fix it, look up W1NC on QRZ.com and ship your unit off to him. I thank the community for trying to help me and I thank Jeff, W1NC, for fixing my construction problems. Jim Brown, W0RLD

Hi all During my absence on family vacation last week there was a major storm last Thursday, a lot of rain and thunder and lightning. After one close-by strike my colleagues reported crackling and sparking on cables in our office, and since then we have been without internet... the ISP say the modem is working fine (they test it from their end) but we tell them it isn't actually delivering us any internet. Anyway regardless of that, today I woke up and figured out how to USB tether my cellphone to the PC and share the internet to the PC. And got my shipping colleague doing the same thing via her iPhone. So 2 of our 6 QRP Labs office computers (which are the most critical two) are back online while we wait for someone from the ISP to visit. We are now working on catching up on the shipments from last Thursday to today. Meanwhile after all the crackling and sparking my colleagues thoughtfully unplugged my antenna. Full marks for effort... but the damage was evidently already done by that time: when I returned from vacation and switched on my QMX+ the thing popped and current went to several amps... I replaced the four BS170 PA transistors (one of which was visibly cracked); still not getting correct power output and performance I realized I need to replace the Q508 Tx/Rx transistor which had also apparently taken a hit. After all that, happy to say everything is back in order, the radio is working properly once again! Meanwhile: we ran out of dummy load kits, and the 1.000 new PCB's are on the way via FedEx. They are going through customs processing in Izmir today and after that the imports normally reach me about 2-3 days later by road via the domestic courier who are the local FedEx agent. So some of you who ordered a Dummy load kit might be wondering why your order didn't ship yet, this is the explanation, please wait a few days. 73 Hans G0UPL http://qrp-labs.com https://www.buymeacoffee.com/g0upl

hi, may i`m wrong with some config, but sending cw from stored messages isn?t possible without loosing some characters, as like as "cq de df4bj" may ends in "ca de dfuba" or something else. Same behavior if sending from logging programm via cat. Did i don`t have correct configs or is that an known issue? I have installed the v1_01_003 , but going back to a non ssb fw doesn`t help. any suggestions ? vy 72/73 de Udo DF4BJ /qrp