Hello again everyone and thanks to those who responded to my last emails. A few weeks later, many more late nights and still no further ahead, but i will disclose what i have found. First off, thanks for all the suggestions. The QMX is not in practice mode, not in protection mode and the Q507 mosfet is not lifted or broken that i can see. I have .3 ohms continuity between Q507 thru inductor L502, thru T501 and then to the drains of the finals. During transmit , i have .33 v from the drain of Q507 (i hope i have that right? It is the flat portion at the top of it just below L502). Source is 12v and the gate seems to drop only about 500mv or so during transmit. I had been told the threshold was -1.5 to -3v possibly on the gate? I just wish i understood it a little better, like the signal path through an old AA5, LOL. I installed my spectrum analyser at the jumper before the BNC and although no appreciable power out, ALL bands are delivering a almost perfect match with the signal being transmitted through the diagnostics mode. But...-20 to -30 db down in the mud. So very low. But it is there. I am lost for now. Does this make sense to anyone? Thanks for any and all help in advance!

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 https://groups.io/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 https://groups.io/g/QRPLabs/topic/109639794#msg133769, indicating the PCM1804. I did the diagnostic tests from https://groups.io/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

Hi I'm having problems with QMX version 4. It receives fine, with no issues, but virtually no RF output. I can hear it in CW mode on another rig but it's weak. Using a current limiting PSU set at 11.5v .05 Amps RX .070 Amps TX. In hardware tests mode the SWR jumps around even when the dummy load is connected. Using the Putty terminal emulator the SWR has very random values in every band. Refreshing just comes up with a different set of values between 1 and 10. I have rewound the Really Weird Twisted Sisters Transformer and turned off the SWR protection. Checked the whole board with a microscope any suggestions would be gratefully received. Cheers Paul M0PNN

I will be doing another CW on the air practice session Thursday 01/02/25 . Anyone 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 roundtable control station. I will do it as a roundtable so everyone gets a chance to transmit. Please listen to my directions. Details: Time - 10:00 AM Eastern Time / 15:00 UTC Band - 40 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 roundtable QSO. Reply to this email if you have questions. IT DOES NOT MATTER HOW POOR CW IS Ed AB8DF

Hi, Got a QMX on the workbench, and pulled up the terminal emulator window to run diagnostics. I'm currently seeing a great yellow trace on the ADC/IQ sweep that looks normal, but a very very erratic red trace. Definitely not a sine wave and absolutely not 90 degrees out of phase. Is this looking synonymous with a PCM1804 failure, or T407? (the trifilar one) being wound wrong? -- Daniel ZL2DTL/ZL4YOTA

Doing some repairs on the QMX I inadvertently used the winding instructions from V2 instead of V1... 23 windings with a 15T tap as opposed to 28 windings and a 19T tap. I didnt realize until I went to check continuity per the v2 manual and had nothing---it still checks out with the V1 instructions, however. Easy to change--but wondered if this was a better design subject to the other additions on the board must have had. Happy New Year to All Scott VY1CO