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Hi all SSB firmware was released into beta on 17-Mar-2025 after 9+ months of development. Many thanks to everyone who bravely helped test it and patiently provided their feedback and observations. There are now quite a few YouTube videos, forum reports and other social media mentions about on-air successes with QMX SSB. Now that it has been at least 6 weeks in beta and I believe most of the issues have been resolved, it's time to promote it to an official version. I have called this version 1_02_000 and published it on the QMX page http://qrp-labs.com/qmx where I have also published the updated operating manual, which grew from 111 pages to 134 pages. The main changes are: SSB (obviously!) including CESSB, TX Equalization, Mic AGC, VOX, Pre-distortion and and and... Addition of up to two more USB Virtual COM serial ports (up to three total). All of the hardware tests such as RF and SWR sweep, and Diagnostics, are now available on the LCD too. New CAT commands for LCD contents, S-meter, AGC-meter, Power meter, SWR meter, SSB source Complete list (relative to 1_00_027 the previous official version): SSB modes added (USB and LCB), with CESSB, TX Equalization, Mic AGC, VOX, Phase pre-distortion and more Rationalization of menus, grouped into CW, Digi and SSB submenus (now Keyer and Decoder are submenus of CW) Added up to two more USB Virtual COM serial ports (configurable) LCD versions of AF, RF, Image, LPF, Test ADC I/Q sweeps (miniature graph on LCD) New function PA mod. test to check operation of amplitude modulator Diagnostics screens are now available on the LCD interface too Now remembers previous menu location on ALL menus regardless of nesting level Add way of forcing factory reset, press Menu (left) button during power-up Change TX color in diagnostics screen from red to blue, to avoid confusion since red things are errors Added CAT LC command to retrieve LCD contents Added CAT commands SA (AGC meter), SM (S meter), PC (Power meter), SW (SWR meter) Added CAT command SS (get/set SSB input source) Bug fix: PTT P did not work properly Bug fix: Incorrect PA voltage display on the Diagnostics screen 73 Hans G0UPL http://qrp-labs.com https://www.buymeacoffee.com/g0upl
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My QMX+ stopped working after a few FT8 calls. One of the BS170 transistors had blown and there was a short circuit to GND via Q507. While I was replacing the transistors, I realized the possible reason for this: The BS170 housings are not necessarily exactly the same height, one of the transistors was loose under the washer and slipped out. I only noticed this because I hadn't soldered them yet. If I had soldered the transistors first and then put the washer on later and tightened it, I wouldn't have noticed this. And I think that was also the problem that led to my burnt-out Q504 in the first place. The heat dissipation to the circuit board didn't work properly because the transistor wasn't pressed onto the circuit board properly. I took another look at the assembly manual. It does not explain exactly how to install the transistors and in what order. I think a comment on this possible problem would be good. gl tu es 73 de J?rg DJ4WD
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QMX+ Power Output
13
I just finished my QMX+ and thought I would share my RF power out readings. I did my best to wind all the torroids evenly though not perfect. Measurements are made with an Oak Hills QRP meter into 50 ohms, and with a LiPo supply voltage of 13.4 volts through a single diode. Voltage at the rig when keyed is just below 12 volts. 73, Gary W8PU 160 m - 5.9 w 80 m - 5 w 60 m - 3.9 w 40 m - 3.9 w 30 m - 3.7 w 20 m - 3 w 17 m - 2.3 w 15 m - 4 w 12 m - 2 w 10 m - 3 w 6 m - 2 w
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Hi all, someone stated elsewhere, that the QMX+ was a good rig for contest. Not really I think. I just used it in the CQWPX as well as my Flex 1500. Well the waterfall is a + for the flex ( I dont want tb buy more hardware to have one for the QMX) and changing the filters directly on the Hercules console is way quicker. I have not updated to the SSB software yet. The 300 hz filter is vy wide on the high side. Strong signals can be heard widely. Nothing after 0 beat. Also strong signals seem to saturate the rx and that was a problem especially on 40 m CW clicks are not nice but that is known. 160 m when the band is used above 1.840 is not workable as all stn from below have a similar signal there again. And then I have still to figure out how to set up the AGC. The hang time on strong signals is too long and that makes life difficult. On the positive side I prefer the audio sound of the QMX+ to the flex. I dont't want to be too critical and I never had a newer state of the art rig to compare. Years back I had a TS 830 and liked that. S next up is the region 1 FD for the QMX+ -- Martin DK3UW
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QMX Kit problems
5
My parents got me the QMX 80-20m kit as a present for getting my license in Australia. This is my first time doing something like this but the challenge was very fun here are my problems- 1. when the case is off, the radio will turn on but half the buttons don't work properly and the screen is so bright that I can hardly see the text. eg turning up or down the right-hand knob will always increase the frequency or setting number. The right-hand knob also won't click down and no settings are saved upon restarting the radio. 2. when the case is on, the radio draws power (about 0.3A at 12V) but only when pressing down the left-hand knob, after letting go no power is drawn and it stays off. I have looked over the instructions and schematics several times, just want some advice on how I can fix this. Thanks VK3AUN
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Hi everyone. With the release of the SSB firmware out of beta, I thought I would make my offer to source K6ARKs wonderful little microphones, which can be found here: https://www.printables.com/model/320559-mini-microphone-for-qmx-trusdx-usdx-kx2-and-kx3, one more time. Adam (K6ARK) made a super fantastic little miniature mic case, and they work with the QMX quite nicely. I print the cases in PLA, and have the following colors available: Black, White, Grey, Navy Blue, Orange, Light Green, Red, Gold, Purple, Sand Stone, Light Blue Stone, Turquoise stone, and Marble Stone (The stone colors look like marble or granite - little flecks of darker color in them - The marble one winds up looking like bleached bone). The kit includes: 3D Printed case in PLA 3.5mm jack Electret Mic Element Microswitch for PTT For each mic, $10 for kit, $15 fully assembled and tested. This price includes shipping in the US. I am happy to make you more than one, some people want one for home and one for the go bag, that's great. You will need to provide your own AUX cable (3.5mm male to male) to go between the mic and the radio. I have had several ask what cord I am using, So I have included this link to one I am using and that I test all my assembled mics with; it seems to work quite well: https://a.co/d/36GDDXf (This is a shortened, non-affiliated link to Amazon.com page for the cable I use) If you are interested, send me a private email, and I will send you payment details. My email address is good on QRZ.
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I received my kit for a high-band QMX this Tuesday, and have been working off and on over the course of the week to assemble it. I've gotten to the point where it's fully assembled, and after several close inspections under magnifying glass and microscope, I can't find any significant defects that would lead to the problems I've been seeing, outlined below I'm powering the QMX from a 10V, 250mA current limiting DC power supply. The core issue is that the board (That I have never programmed) is drawing far more current than the assembly document suggests it should at this stage) The different cases I've run: Main board connected to power, no additional boards attached: 0mA drawn Main board connected to power, PS #2 board attached, all others detached: 0mA drawn Main board connected to power, PS #1 board attached, all others detached: Initially current limited to ~8-9V @ 250mA. After an inrush period, stabilizes to 10V @ ~100mA Fully assembled QMX: Current limited to ~6V @ 250mA. LCD screen turns on with solid black squares displayed. Appears as a usb device immediately upon plugging in to a computer, without pressing the potentiometer button. I've been focusing my troubleshooting efforts on the interaction points between the main board and PS #1, and haven't found any obvious shorts. Checking the pin header connection to PS #1 with the board attached, I didn't see any shorts to ground. I also double checked and ensured that there weren't shorts around the power amp transistors, and around X201 where I saw VCC being used. I've attached photos of the back side of the main board, and front side of PS #1 as installed under a magnifying glass below. If any other pictures are required let me know and I can provide. Note that there is some debris near the PA transistors in the second photo. I cleaned that and tried again, and the board still enters the current limited condition. Thanks and 73 de VA3KBY
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as I was directly asked here are some pictures of what I used to make mine. -- Martin DK3UW
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Hello. I'm assembling a 50 watt power amplifier for use with a QCX+ that I assembled last month, for the 80 metre band. I have very high harmonics at the output of T3 - as a result, I get only about 9.3 watts out when running at 13.8 V. Output from the LPF looks OK on the 'scope. I found the excellent videos by NA5Y which shows the output of T3 should be much closer to a sinusoid than what I get. I also found the discussion with KO1KR in August of 2020, but unfortunately I can't see his scope photos so I don't know if he had the same problem. I've since skimmed through the many discussions on this forum but haven't found the same issue exactly, though I did check out some of the suggestions given here. I found the amplifier took 67 mA with R5 fully CCW - I adjusted R5 till the amplifier drew about 70 mA with the QCX+ key-down in practice mode. Here are my scope traces: 0092 is the gate drive, yellow is Q1 gate, purple is Q2 gate - all is well here. 0090 is the drain voltage, Q1 in yellow and Q2 in purple - these look like there is oscillation ? 0091 is the voltage at the output of T3. This has a lot of third harmonic and doesn't look like the waveform NA5Y showed at this point. (QCX+ was set for 3.520 MHZ , amplifier connected to a dummy load.) I thought that perhaps my bench power supply is doing something odd when the amp is drawing power, but I probed the 12 volt line right at the barrel connector and the 'scope showed almost no disturbance of the +12 v supply. In frustration, I observed the output of T3 with the 'scope set for a long capture - it almost looks as if the distortion grows with time, for the first few tens of microsceconds the scope showed a small but sine-ish waveform, which over the span of a few hundred microseconds got wigglier and wigglier till it developed into the mess seen in my scope capture 0091. I've checked DC continuity to the windings of all the transformers and coils. I did find a bad joint on the primary of T1 but I cleaned it up and can now get power out of the amplifier. I haven't yet checked bias on all the 1N4007 diodes but the input looks quite sinusoidal at R3 closest to the input. The few watts the amplifier does produce look OK at its output. The QCX+ makes about 4.3 wats into a dummy load (43 V peak to peak) at 13.8 V DC. I'm assembling these units for a friend, and I had really hoped to have them ready for Field Day this year. The instructions are excellent and I have followed them closely. What can I look at next? Bill VE4STW
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Continuous tone on 14.053.5
2
My home built QMX+ seems to be working great, starting to make good CW contacts as a rank beginner, but I have a consistent continuous tone on 14.053.5 regardless of antenna connected or not. Any pointers where to look? I have not installed any of the new ssb firmware.
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Programming Troubles
2
I recently purchased an assembled QCX Mini. I absolutely LOVE this transceiver and I have been using it everyday on W1AW for code practice. I also copied the instruction manual and put it in a neat spiral spine, including a sturdy cover and I keep it beside my transceiver at all times for reference. Soon I plan to go on the air. My problem is, the way to program it is not sinking into my elderly and challenged brain. I'm sure the manual is written well but I often have problems understanding technical instructions so this, by no means, is a problem with the manual. It is instead, a problem in how I process information. Has anyone out there created a "cheat sheet" with step by step instructions? Example: Step 1, Do this. Step 2, To save your setting, do this, etc. Thanks in advance for any advice or "cheat sheet" you can provide. 73. .
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QMX+ - LPF array design question
Let me start by saying there is no evidence that the situation I will describe is occurring or has ever occurred in a real QMX+. There is nothing here to worry about. It is most likely just something I am doing wrong so no panicking! OK, I have set up a model of the entire QMX+ lpf array. I have figured out how to make the diode model give a long reverse recovery (Vp parameter). The issue is not with recovery though. I am seeing something that is clear and yet must be wrong. The situation is that I have LPF4 enabled and the others disabled (by switching the gate of the correct BSS123). I set up my source to drive a signal big enough to generate 5 watts out, roughly 22 volts peak. I set up the sim to run without signal for 10 millisecnds to give the simulation time to stabilize the various voltages, mainly the time needed to charge all of the lpf shunt capacitors in the disabled filters up to 12-.7 volts. At that point I discovered that it is a bad idea to simply switch on the 22 volt peak input signal full blast because it ends up creating a large enough input to forward bias the unused filters input diodes. Once the diodes switch on, they cannot turn off until the input signal stops (28MHz period is way less that TRR of the diode). Switching on the lpf0-3 filters puts a near short on the PA output and kills any chance of the doubler getting the reverse bias up above 22 volts so it is fatal. OK, so maybe I need to "shape" the PA output. I "modulated" the input signal amplitude with an RC charge and here is where I ran into the issue. If you do the math on LPF0 capacitors (4400 pf total) charging through a 470k resistor, it takes 5 milliseconds or more to charge. What I found is that I had to use 5-6 milliseconds of "shaping" on the startup of the input signal in order to avoid tripping the LPF0. This seems too long to me but it looks like it is the way it is designed. Note that these diodes are OFF and get turned on by the large input. This has nothing to do with TRR (which is for ON->OFF transitions). This seems to mean that filter input amplitude transitions that rise above 12 volts must do so SLOWLY. Everything in the model seems to be doing what it should. The doubler doubles and the bias begins to rise when the input approaches 12 volts amplitude but it rises at different rates on the load side of the six 470k resistors with LPF0 being very slow and LPF6 being much faster. I have to raise the input amplitude slow enough to avoid turning on the LPF0 input diode. So, where am I going wrong? I have never used a PIN diode but I THINK I understand how they are supposed to function as switch. Is there something that keeps them from turning on quickly? Again, this is SURELY a red herring. But I would really like to make this work right so I have to ask. Thanks, Tony AD0VC
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QMX+ lucky streak ended
12
Everything has gone textbook right for my QMX+ (kit built) for a few weeks now, but I knew it couldn't last. I was receiving with the USB connected to a Raspberry Pi 4 running WSJT-x and it seemed to be working fine. Then I looked back and the display was dark. Pushing the startup knob drops the regulated voltage to 11v and current limit of 600+mA, which goes back to zero mA when the push knob is released. No idea what happened, but it's down to the basement "bench" to take a look. Film at 11..... -- Brent DeWitt, AB1LF Milford, MA
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Updated Wiki Page: QMX QMX_plus Debugging
#wiki-notice
The wiki page QMX QMX_plus Debugging has been updated by @Ludwig_DH8WN <DH8WN@...>. Compare Revisions
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QMX+ - Should there be resistance between T501 primary and secondary windings?
Greetings all, I am currently assembling a Rev 3 QMX+ and have a question regarding T501. When it comes to continuity between an A point and a B point, my DMM (a Fluke 12) does not beep, though it does display '2.006' on the screen. If I switch the meter to measure impedance, measuring from any A point to ground or a B point results in the meter showing a resistance of 9.77k ohms. Is this to be expected? Note: when I was separating out the winding leads when winding T501, there was NO short-circuiting between the primary and the secondary. I appreciate the help! Charles Johnson PS While I don't think that it would make any difference, for the record, L502 has already been installed, but the BS170s have not (I'm going to socket them, which means that it's easier (at least for me) to install T501 first).
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QMX SSB low output
15
Greetings to the brain trust. I have a kit built QMX which is awesome and works great on CW. I have upgraded to the 1.02.000 ( the latest firmware) and added a QRP GUYS mic. Everything seems to check out in the hardware tests, but it seems very low output on SSB. I've set the mic. gain to 75 which seems to help, some. Any ideas on trouble shooting? Thanks in advance. WX7J Doug
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Thank you Eric. Got mine this week and transmitted SSB for the first time after 45 years off the air. Great mic at a terrific price. Now back to my regularly scheduled CW practice. 72 WB0ZJJ South Florida
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Elecraft T-1 tuner usage
14
Could someone please explain to me a simple, quick, non-fiddly way to send a signal that my T-1 tuner can use to tune itself? I tried searching the forums but didn't find anything. Thanks all.
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QMX+ CAT PTT bug?
4
Rev 3 QMX+ running WSJT-x 2.7.0. When running with USB audio mode (SSB mode on QMX+), selected in both the QMX and WSJT-x the TUNE/TX ENABLE or PTT test only gives a momentary PTT signal the first time, try again and it keys the QMX+ correctly. In digi mode in both WSJT-X and QMX it works 100%. Anyone else seen this please? 73 Ken g4apb
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FDIM 2025 - Bringing SSB to the QMX (Hans's presentation)
10
Enjoy https://www.youtube.com/watch?v=bsDBcFXgHbY 73 DE muhsin TA1MHS
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Sat 8:39am