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What it does: use the LCD to display characters received on the CAT serial port and characters transmitted over the serial port. The RX data could appear on the top line and the TX data on the bottom line. Perhaps an indicator of some sort that shows that data is being received by the QMX. even if the data can't be decoded as printable ascii characters. Perhaps, when the CAT/serial monitor is active then disable the terminal applications mode so that a newline character on the serial port doesn't take over the port for terminal applications. Why? I've been developing microcontroller code to read VFO A on the QMX and display frequency and band info on a remote LCD. I first wrote a QMX CAT simulator program so that I could test and debug the microcontroller code easily. Also I have verified with PuTTY that the QMX responds correctly to incoming CAT commands. When I connect the microcontroller via USB to the QMX I am unable to establish that the two are communicating. This CAT/serial monitor diagnostic tool would help me answer the questions: Is the QMX receiving serial data on the CAT com port? What data CAT commands/data is received? What is being sent by the QMX over the com port. This little rabbit hole opened up with this thread: /g/QRPLabs/topic/scripting_language/112779657 In which I suggest the OM use a microcontroller to speak CAT to the QMX. But then I asked myself if I could actually accomplish what I suggested and, here we are. I am aware of 8.7.3 CAT command test and 8.7.4 CAT monitor in the manual but it's not clear to me how to connect both a terminal and microcontroller to the QMX over the single USB-C port. It would be very helpful if the QMX itself could tell me on the LCD what is happening on the serial port. Thanks and 73, Matt

The wiki page QMX QMX_plus SSB Calibration and Predistortion has been updated by Stan Dye <standye@...>. Reason: Added new intro material, including what works if you don't calibrate, and the risk some few users have encountered in burning finals. Compare Revisions

On my mid-band QMX ....I wasn't going to do it. I'd read several horror stories but then, as an "experimental amateur radio station operator" I couldn't help myself. The SSB calibration routine was a disaster. Blew the 2A inline PSU fuse, and took out the BS170s. I replaced the BS170s with new ones on hand and applied enough heat, visually checked for other damage (none found), then sparked it up. Receives fine and all functions appear to work (Mode, Volume, Step, Band etc). However, when I try to transmit on CW into a dummy load, I'm only seeing about 340mW on 40m and progressively less as I go up in frequency... Any ideas as to where to turn to next would be very much appreciated... 73, Robert VE7ZN

I just built a Pacific Antenna mic kit for my QMX+ and it works great!! If you need a mic for your QRP-Labs transceiver kits I would look at this unit. Very simple to build and inexpensive. 73/GL

President Trump has signed an Executive Order that ends the tariff/duty exemption on small value shipments (i.e. < 800 USD) sent from China to the US. It is not made clear if this change will apply to shipments from other countries as well. This will certainly impact those of us who purchase PC boards, electronic components and modules, and equipment in pursuit of our hobby. 73, Ben K0IKR Here is text from the US government: ¡°Today, President Donald J. Trump signed an Executive Order eliminating duty-free de minimis treatment for low-value imports from China¡­¡± ¡± Following the Secretary of Commerce¡¯s notification that adequate systems are in place to collect tariff revenue, President Trump is ending duty-free de minimis treatment for covered goods from the People¡¯s Republic of China (PRC) and Hong Kong starting May 2, 2025 at 12:01 a.m. EDT. Imported goods sent through means other than the international postal network that are valued at or under $800 and that would otherwise qualify for the de minimisexemption will be subject to all applicable duties, which shall be paid in accordance with applicable entry and payment procedures. All relevant postal items containing goods that are sent through the international postal network that are valued at or under $800 and that would otherwise qualify for the de minimis exemption are subject to a duty rate of either 30% of their value or $25 per item (increasing to $50 per item after June 1, 2025). This is in lieu of any other duties, including those imposed by prior Orders. Carriers transporting these postal items must report shipment details to U.S. Customs and Border Protection (CBP), maintain an international carrier bond to ensure duty payment, and remit duties to CBP on a set schedule. CBP may require formal entry for any postal package instead of the specified duties. The Secretary of Commerce will submit a report within 90 days assessing the Order¡¯s impact and considering whether to extend these rules to packages from Macau.¡±

I have been running firmware 1_02_000 on my QMX+ with good results on CW and SSB (haven't tried Digi yet) since the release of that firmware. So yesterday, I updated my original QMX with 1_02. The update went fine, and operation on CW was great, but I can't get all the SSB calibration procedures to look right. This is an 80, 60, 40, 30, 20 QMX, built for 12v (same voltage as my QMX+). The cals failed to complete on 80, 60, and 30. On 80 and 30, I get an error message saying "Change over 30 degrees" from the phase error cal and it stops at about dac=~1100 to 1300. I got a similar error on 60m, but this cal ran successfully on 3 subsequent runs. On the USB IMD sync, the final table in the upper right says 80m:15, 60m:74, 40m:23, 30m:62, 20m:26. In addition, 80m and 40m responses were almost flat - 80m ~140, 40m~100. On the LSB IMD sync, the final table in the upper right says 80m:74, 60m:74, 40m:29, 30m:15, 20m:26. In addition, 40m and 30m were almost flat - 40m ~280, 20m ~ 250. Also, for whatever reason, the y-axis max on 80m was ~7000000, and the y-axis max on 60m was ~1000000, both 1000 times higher than all other bands. On the ADC I/Q tests, the curves looked about the right shape (compared to samples in the oper. manual), but the upper left and lower left numbers were not very symmetrical. 80m 42183/-42067 60m 52338/-52457 40m 55808/-56412 30m 53881/-54284 20m 36459/-35947 Mic test works fine. PA Mod test looks good. Diagnostics look good on all bands with the following RF outputs. 80m 4.0w 60m 4.3w 40m 4.4w 30m 3.7w 20m 5.4w All tests with dummy load with Diagnostics showing SWR around 1.1:1 Any comments or suggestions are welcome. 73, Randy, KS4L

Last night while playing with my qmx the receiver went deaf. This happened after txing on ssb with IQ mode on and panadapter open. I was using a mic connected to the radio. The S meter with antenna dropped to nearly nothing and I can only hear white noise now. The radio will still put out 5w. I ran my little signal generator into qmx and on receive I hear nothing at -33dbm. At 0dbm (I know quite strong) the signal will get through. Any thoughts? Thank you Ryan KK6DZB

Recently, I sent my Rev 1 QMX, which I had problems with the right encoder, and not able to load the new firmware. Mr Moore, troubleshoot the radios, and fixed the issues he found, then did a complete test of all the features, and clean any possible cold solders, or spaltters of solder. Then provided a detail report of what he did, and parts that needed to be change. All of that for just a small donation. Thank you very much Mr Moore, and looking forward to have lots of fun with my improved QMX. Ed Cortes K4BQN

Hi all, This is my first post here so I hope it lands in the right place. A while back I purchased the U3S kit and having constructed it found it to work perfectly on the single band . I have just added the LPF relay board to provide an additional 5 bands. The U3S board has the relay fitted and diode along with the LPF and I have removed the 2 relevant wire links. I must be programming the U3S board incorrectly as the unit only transmits on Band 0, that is it will only show its transmitting on band 0 even though I have set the 5 new bands with band 1 being the highest in frequency. Can anyone shed some light on what I could have missed, Thanks. -- Steve Shuff.

Hello, Has anybody tried this microphone preamp : https://www.analog.com/en/products/ssm2167.html Evaluation boards can be found for about 5€ looks good to me but I am no expert ! 73, Yannig - F4IUJ

I know¡­.. lots of postings on QMX+ microphones here. Does anybody have a single list of working good/cheap mics? Thanks de K2RMA

I finished my QMX+ build last week and it is time to admit this is the first kit in my entire life that doesn't work right away, dating back until about 1980. Since all those other kits worked just fine, I never invested in lots of bench hardware nor are my trouble shooting skills well developed. So, having just finished my piece of humble pie, I am trying to figure why my LCD remains blank. The backlight works. There are no characters or blocks, regardless of the potentiometer setting. I haven't hooked up an antenna or earphones so I don't know about the RF/AF sections. I was able to get my Linux Mint PC to connect via USB-C and using Putty, I put the QMX+ into firmware update mode. It was 1.0.27, now it's 1.02.00 as the firmware update worked fine. The terminal mode confirms that the firmware update went okay. I can browse the terminal mode. All of the front panel controls show "Press", right or left arrows as is appropriate for the control. The only thing is the display never shows anything. It is completely blank. I disassembled the case and removed the front pcb and checked every solder joint on the connectors on both the main and front pcb's. All look good, shiny, no bridges, dry joints, nor whiskers. I'm looking for advice. All I have is a DMM to test with. Lincoln N9IN

Hey guys. Any idea where i can buy the electret capsule, working with the QMX - AOM-5024L-HD-F-R? I have found it only in Mouser and Digikey and the minimum shipping price is 20 euro. Any ideas of other compatible mics with -24db sensitivity? Thanks in advance, 73 de LZ3OM

I posted here before about building a 40-10 qmx. I did a little more looking and thinking. Looking at AI6XG's mod: https://www.ai6xg.com/post/a-40-10-meter-qmx#viewer-cl0z424097, it seems to preform well and has motivated me to go out and buy a QMX. However there are some questions that I have that I want to confirm/ask. In the blog, he mentions: "According to simulation, adding 100pF to the already installed C402 56pF should lower the peak frequency to about 11MHz. I found that adding 150pF instead, for a total of 206pF, provides good results" In the conclusions, he says to use a 210pF capacitor in C402. However, such a capacitor does not seem to exist. There are plenty of 200pF and 220pF capacitors on the likes of digikey and mouser, however I can't find a 210pF capacitor. Since he says adding 100pF should work, would a 150pF, 180pF, or 200pF capacitor work in the place of a 210pF one?

Hello all, Recently completed a mid band QMX build. First serious electronics kit build and I'm a bit out of my depth for sure. But after correcting a few mistakes during the build I powered on the QMX with a current limiting PSU and ran through hardware test last night on a dummy load. All appeared well, or at least the sweeps matched what the manual describes and what others have posted. CW transmit into the dummy load was no problem and between 4-5W on all bands. This morning I decided to try SSB Calibration. Hooked up to the benchtop PSU and a dummy load and let the QMX run while I did some computer work. About a third of the way through I heard a faint crackle and looked up to see 1.5A draw on the power supply and 7V. QMX was still trying to perform calibration. I shut down the PSU and smelled some hot electrical components. Disassembled and do not see anything obviously wrong. I decided to power it back up and this time connect to the terminal diagnostics. QMX powered up but right after the firmware splash screen it immediately began drawing 1.5A again. I quickly connected to the terminal application and as soon as I did the increased draw went away and the diagnostics screen showed normal readings. The moment I disconnected the terminal app the draw came back. Hot electronics smell persists. This is where I don't know enough to continue to track down the issue and am looking for help. Any advice would be great. Thanks, Mike KR4CNM

I am having difficulty getting the compressor to work on my QMX+ on software 1_02_00. There are no performance issues with this build and the SSB calibration runs fine. When I use the config settings shown in the manual pictures the audio sounds good on a nearby receiver using an external mic. This is with the compressor off, the default. If I go back into the terminal and turn on the compressor I get high distortion. It is nearly solid noise and transmits near peak power continuously. It doesn't matter what compression value I use, always the same. Even a value of zero. If I unplug the external mic and plug in just a PTT switch, I get the same noise. The only way to get the noise to go away is to do a factory reset. Again, SSB is all good until I turn on the compressor. I have done factory resets twice now. I would really like to use compressor to add some punch but I haven't been able to figure out what I am doing wrong. -- Regards, Earle KC0KVR