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Release of version 2.0 of ABS solution for QMX+ (Automatic internal antenna tuner, internal battery and internal speaker with audio amp)
29
#PSU
#QMXplus
#audio
#ABS
#ATU
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).
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QMX snags epic DX during greyline!
3
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
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Just finished assembling a QMX plus. Went to put in a case and it doesnt fit. The front panel PCB is wider that what is pictured in the manual. It appears that it didn't get trimmed properly by the manufacturer. This is the picture from the manual, the yellow boxes represent the extra parts my PCB have. what would be the best way to trim these pieces off without damaging anything?
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Record number of assembled transceivers shipped in March
2
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
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QMX repair
4
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
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QRP Labs kit shipping update
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
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QMX+ messages are loose some characters while sending
#anomaly
#cw
#messages
#missing
#QMXplus
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
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Does anyone else hear this constant 750 Hz square wave through the speaker while the QMX transmits a CW, FSKCW or WSPR beacon message only when the QMX is in USB or LSB mode? While the QMX is in CW or DIGI modes the speaker remains silent during beacon transmissions . Watch my video at https://www.youtube.com/watch?v=d-me0UrO1dQ QMX+ transceiver with Firmware 1_01_003
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Hello all, My QMX suddenly shuts off at around 10.5V. Is it normal ? I can't recreate it but last summer I think had it giving me high voltage warnings when in fact, voltage was low even if I didn't understand at the time that the radio was suddenly shutting down when voltage is low (/g/QRPLabs/topic/110264408#msg135921)... It is problematic for me as I use a nominal 12V drill battery that goes down to 10.5V relatively quick before stabilising there.... I've already fried the SMPS once so I have a new set bought in April 2024. I am not too sure how to investigate this further. 73, Yannig - F4IUJ
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Internal mic seems to be working?
8
#qmx
#ssb
I've just tried transmitting SSB using the internal mic to a dummy load, with my K2 next to it to receive the SSB signal and record the audio. Although the background noise was loud whenever I pushed the PTT button, my recorded voice was also loud and clear. I set the mic gain to 60 and compression to 10. So the internal mic is already useable I guess? Anyone tried the internal mic to make a real contact? Yoon KM6KJI
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Thanks Hans!
Just finished "building" my QMX+ and everything works as advertised! Got lazy and tried a couple of FT8 contacts on 20. Kentucky, Indiana and Brazil in short order on an end-fed dipole. I'm impressed, Hans. Thank you for the contributions you've made to the community. -- Brent DeWitt, AB1LF Milford, MA
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For Sale
3
I have a nice QMX+ and QDX for sale. The QMX+ has a case and GPS unit installed. Work good. Typical power outputs. It has the SSB software but has nor been calibrated. $185 shipped to CONUS (Lower 48) The QDX has the case as well and also has the typical Power outputs. $90 Shipped to CONUS Email markf1952 at hotmail dot com N5MF
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Qmx ft8 linux
2
I had been trying to figure out why I could not make any ft8 qso's. Seemed wsjtx was connected, got audio in my ear when transmitting. Would change radio bands. Turns out I missed when reading the manual, make sure computer volume is set to 100%, and no more. Mine was at 150%. Working great now. It always seems to be something I did wrong. Hope this helps someone.
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Broken L512 toroid.... T37-10 (Black)
5
#toroid
#problem
I've broken one of the T37-10 (Black) L512 toroids. Do you know where I might get a replacement? Thanks, Bill
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On 4/07/25 I had a CW practice / rag chew session on 20 meters. I worked four stations: Date / Time Call Bnd Frequency Mode Power Rec Snt Name SPC# Comments Off 4/7/2025 14:40 W0GIB 30 10.115 CW 100 579 559 Craig MN K3 at 100 watts 100 ft sloper doublet 15:23 4/7/2025 14:05 K4HPP 30 10.106 CW 5 559 559 Jim TN K3 at 5w watts 100 ft sloper doublet 14:22 4/7/2025 13:21 K7MOA 20 14.045 CW 100 599 559 KEITH TX K3 at 100 watts 100 ft sloper doublet 13:32 4/7/2025 13:00 KI5JG 20 14.045 CW 100 449 339 Jim TX K3 at 100 watts 100 ft sloper doublet 13:17 Conditions were OK. 30 meters seemed to be better than 20 . SSN = 140, SFI = 167, A = 20, K = 2. My next CW practice session will be April 08 at 09:00 EDT / 13:00 UTC on 30 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 08 2025 Time - 09:00 EDT 13:00 UTC Band - 30 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_._,_._,_
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Does L502 cause excessive voltages on the QMX finals?
22
The four BS170's and T501 are arranged in a standard voltage mode class D push-pull amp. The center tap of T501's primary is normally a DC voltage source, as it is on the 50W QCX amp. When one set of BS170's pull one side of T501's primary to 0 volts, the other side pops up to 2xVdc (so 24v if operating from 12v). And then the other set of BS170's pull the second side low, creating a square wave at the transmit frequency with a pk-to-pk voltage of 2xVdc across T501's primary. Since the LPF on the secondary of T501 allows through only the fundamental to the 50 ohm external load, the harmonics are blocked by the LPF on the far side of T501, and the current through T501 is a sine wave. The current drawn from Vdc at the T501 primary center tap is a rectified sine wave. Seems to me that adding L502 would enforce a constant current into the T501 primary center tap, not a rectified sine wave. And that the extra current with nowhere to go would be piling up, causing excessive drain voltages that might blow the BS170's. The above paragraphs were originally buried in message /g/QRPLabs/message/139736 Attached is an LT-Spice simulation schematic of the QMX final at 3.57mhz, with and without L502. I'll place a copy of that simulation schematic in the files section under KE7ER. It uses 2n7002 FET's since that is what was handy under LT-Spice. With L502, the Vds on each BS170/2n7002 is very abrupt and spiky, roughly double what it is without L502. Without L502 the voltage across the drains is close to the expected square wave, but output power is reduced. Currents from T501 are rather ugly in both cases, but close to a square wave with L502 and close to a sine wave without L502. I find it curious that a square wave current can exist there since the LPF should be blocking it. The simulation shows the fundamental current going through L508/L1, and the harmonics going down through C515. So the LPF behaves differently than a series LC filter would, and perhaps differently than what would work best with a voltage mode class D amp. It seems that T501 is expected to pass some of the odd harmonics on all bands of interest for this to work well. A very tall order at 50mhz for a transformer that must also work at 1.8mhz. Comments? Jerry, KE7ER
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QMX+: Broken L102
3
I finished building my QMX+ today and on inspection I see I've broken the core of L102, one of the switching power supply inductors. It looks like both leads of the winding are still connected to the board. I'm not going to try powering it up until I get a couple of questions answered. 1) It looks like the core snapped off almost flush with the bottom flange, which is still attached to the PC board. The ends of the winding are still connected to the board. Would it still work if I just used cyanoacrylate glue to put the core back together? 2) If the answer to #1 is "no," can anyone suggest a suitable replacement inductors that's available in the U.S.? Digi-Key doesn't seem to carry anything of similar size that's greater than 220 uH. This one is 330 uH. Dave, WD8CIV
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Good evening! Big thank you to Hans and everyone else in this forum! I had a lot of fun building these kits and I couldn’t have successfully completed them without the folks who ask and answer questions here. I wanted to make this post to thank everyone but also to detail some of the problems I encountered, the equipment I used, and also how I resolved them. This is a long post for anyone who’s interested but TLDR: I built 2 QMX+s and 1 QMX and all three needed new PCM1804s. I purchased a QMX+ in May and a couple weeks later got to work. I had built a couple other kits and antennas previously but this was the most involved so far. I was able to make it through the build and load firmware but I couldn’t run all of the self-tests and the audio was loud static. I didn’t have enough experience or equipment to troubleshoot myself but luckily Jeff Moor W1NC reached out and offered to help. See /g/QRPLabs/message/126274 for my original post. I mailed him my QMX+ and he got it back to me in about a week with several fixes. It had several bad joints, insufficiently scraped enamel, a bad PCM1804, and a bad inductor. Thanks Jeff for your knowledge, experience, and willingness to help the community with your excellent service! I’m extremely pleased with the outcome and my QMX+. I used: A Weller 70W digital soldering iron 63/37 Kester .20 solder 30X/60X loupe https://www.amazon.com/gp/product/B078N34WZR/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 LED Head Magnifier https://www.amazon.com/gp/product/B07T4KPYN2/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 Crescent shear cutter/pliers set from Home Depot A couple of different helping hands type devices Solder wick & plunger type desolderer Flux paste I primarily used the conical soldering iron tip with success but in retrospect, I should have primarily used the wedge tip. The head magnifier with 3x magnification, plenty of light, solder wick, flux, and desoldering tool were critical. The loupe was ok but the head magnifier would have been enough. I ruined the side-cutters on solder wick. Pleased but not content apparently because in July, I purchased another QMX+ so that I could use the lessons learned from the first unit and hopefully successfully build another myself. The kit stayed in the box until my wife & kids went on vacation for about a week. Over a couple of evenings, I had a great time building the kit, using all my new knowledge and experience, but when running the terminal tests, I had bad results on Audio Filter Sweep/RF Filter Sweep/Image Sweep/ADC IQ test. I reworked some of my joints but to no avail. Some example scans, before and after 1804 replacement, are attached. With bad PCM1804 I started diving into groups.io posts and determined that maybe I should invest in more test equipment and that I might have a bad PCM1804 chip. I ordered two more PCM1804 chips (just in case I ruined one). I also ordered a QMX because I was more confident in my kit building skills. In the mean time, I also purchased an LCR meter, a TinySA Ultra (for its signal generator), and an oscilloscope. Probably overkill but I had my eye on them for a while. Over the winter holiday break, I built the QMX. I enjoyed and had more confidence in my build but I had very similar problems to my 2nd QMX+ build during self-tests. During this build, I used a grounding strap/bracelet the entire time so I was pretty sure it wasn’t static discharge related. What are the odds I’d have the same problem twice? I found this post /g/QRPLabs/topic/109639794#msg133769, indicating the PCM1804. I did the diagnostic tests from /g/QRPLabs/wiki/37111 and determined that replacing the PCM1804 was my next step. Luckily I had two new PCM1804’s in stock although I previously intended on only needing one. After doing research here and on youtube for replacing SMDs, I got a ChipQuik kit and a hot air rework station. After doing some tests, I decided I would just use the ChipQuik, which is basically easy-mode for low-skill chip removal. My process was basically, remove the c
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QMX WSPR Anomaly
4
I was trying out WSPR with my high band QMX with settings as depicted in the instruction manual. I had my QLG2 attached and working with the green light blinking. I had the transmit set to 4 after the hour as in the instructions, and when that time arrived, the rig kicked into transmit mode. All appeared to be going with when the display suddenly changed to read the following: 14,097,140 CW 5 0 On the next line: VK4JAZ QG62 30. And there it remained, as if stuck. After a good few minutes I shut it down as nothing appeared to be happening. Any ideas what this means?
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Everything seems good when tx 0 watts jumper in were do I start to trouble shoot?
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Image Name
Sat 8:39am
Sat 8:39am