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SSB Calibration question
3
I have two QMX rigs, one I built (mid band version) the other I ordered assembled. The one I built was successful with the SSB calibration. However, the one that I received assembled from QRP Labs (high band version) fails the initial phase calibration on 20 meters, but passes on 17, 15, 12, 11 and 10. After which the all the bands calibrates fine with USB and LSB. I'm not a big SSB phone guy, but out of completion I would like to know if I should send back the High band QMX. I did the configurations via a USB cable and Putty in Linux. I haven't tried to initiate the calibration via the radio tools without being connected to a computer. Any suggestions?
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I plan to build a QLG2 GPS Receiver Module to use it with my QCX+ I will add: - the blue LCD accessory kit; - the Customized case kit (enclosure). I guess I will have to order it with the "Front blank cut/drilled plate. But what rear plate will I have to order? I might better build the Clock kit with its enclosure and the QLG2 GPS but will the GPS be inside the Clock enclosure? 73 - Pierre - FK8IH
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QMX 1n4007 diodes
12
I needed to replace one of the 1n4007 diodes in my QMX (I cut the lead for an experiment) so I went looking for a replacement. None of the 1n4007 diodes at Mouser have the small diameter leads like the ones from QRP Labs. They are all about .7mm diameter where the QRPLabs diodes are more like .3mm. I ended up ordering Vishay diodes with the fat leads. I had cleared the holes with the solder sucker but the leads still did not fit so I used some PCB drill bits to clear the holes and finally got the diode in there. Hopefully the via barrel is still intact. I am waiting for some caps to put it back together and try it. Any discussion about these diodes? My experience is that 1N400x diodes all had fat leads. Thanks, Tony AD0VC
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QDX: low power on all bands but 80m after PA died
3
Hey everyone, short story: After one of the PA transistors died, I replaced all of them. Now I only get 3,5W power on 80m but less than 0,5W on the other bands. Is this because of insufficient (fake) replacement transistors or could something else be damaged? long version: I built the QDX and after some wire pushing on the coils I got 5W@9V at all bands and was super happy. I am measuring DC on the detector diode of a QRP dummy load. After a some FT8 operation using an antenna, the output power dropped to 2.5W on all bands. Then I accidently shorted one of the transistors during some measurements and the output power went to a few mW. I removed the BS170s from the circuit and measured them using a diode tester and one was definitely broken. Then I bought replacments for the BS170 transistors at three different online shops (not really trustworthy ones). However during testing after replacing the transistors, the QDX behaved identically with each of the different BS170 sets. There was about 3,5W output power at 80m but only less than 0,5 W on the other bands. I supect that the transistors are fake because their performance decreased with higher frequency. But I am not sure. Is there a way to validate this? I used a LCR-T4 transistor tester to measure the transistors. This showed differences in capicatance. The original BS170s from the kit have 50pf, one of the sets I bought has 60pf and the others 30pf. Does this give any indication if the parts are correct? Or could it be possible that someting else in the QDX is broken? Maybe the IC that drives the PA (74ACT08)? However, I measured 2.5V at the BS170 gates so I guess it still works. Unfortunately I do not have an oscilloscope at the moment. Or is maybe the PIN diode switching circuit for the LPFs not working anymore? Reception is still fine! I would be really grateful for help on finding the issue! regards Chris
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Calibrate the QMX's time through Android APP(FT8TW)
6
I wanted to try using WSPR, but every time I reboot, I have to set the time on the QMX again. A friend told me there's a GPS module that can help calibrate the QMX's time. I thought to myself¡ªmy phone already has GPS, so why buy an extra GPS module just to set the time on the QMX? So, I added a feature to calibrate the QMX's time through FT8TW. https://youtu.be/l8dey0vc6_E
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Jeff Moore
Jeff has done it again! Repaired my mid-band QMX - a couple suspected cold solder joints and improperly wound T507 (how¡¯d I do that?). Included was a free wax and polish (Jeff removed caked solder flux and scrubs the board with alcohol). All done in a day or two. I had my QMX back in ten days (could have been faster but that¡¯s our slow postal service). it is so nice to know that Jeff is available to bail you out should your build fails. I¡¯ve built two QMXs and he¡¯s made them right for me. Thank you Jeff! And Hans! (his info is on QRZ) Phil K3UT
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Hello everyone, I've seen in different topics that T507 solder joints should be checked & reflowed in the event of a high SWR spike on SSB transmit... a problem that several of us have mentioned, and in my case, makes the rig completely unusable on SSB. I do understand, looking at the schematic, how this could cause the protection circuit to trigger. What I do not (yet) understand is why this would be a problem that I see on SSB only, and not on CW. I have not witnessed this on CW. A theory I have is that maybe if the joint is just on the edge of continuity, then a higher duty cycle CW signal would temporarily "anneal" the bad joint, but that on SSB you don't have that effect. I am a skeptic about my theory...in any case, I do plan on trying reflowing T507 and associated circuitry. This was a factory assembled unit so I was hoping to avoid this, but I appreciate all that Hans is doing. I'm not complaining at all... just looking for guidance and thoughts so I can get this amazing rig on SSB. God bless, Joel W9JFK
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Hi SWR, sometimes
12
This seems to be a complex problem because I do not understand what is happening. I will try to explain as best as I can. QMX mid bands built for 12 volts and Z-11 Pro auto tuner. I start on 40 meters and go to hardware then SWR tune and start the tune. The tuner light move and ends when a <1.5 SWR is reached. I then go to iambic and send CW at about 20 wpm. After about 10 dits the tuner jumps up to over 4 and the S protection letter shows on the screen after the last number. I cycle the menu, go to hardware, SWR tune and it shows <1.5 SWR. I go back to normal CW and the same pattern shows up again. It happens on multiple bands and is frustrating because I can't complete a POTA contact let alone a ragchew. My sBITx is also low power 1 - 4 watts and does not do this action with the tuner. Any ideas where to look? 73, Dean/ N2TNN
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Received the kit from FedEx in a perfectly intact box. The content check was positive with the exception of the L501 inductor with the partially broken edge. Can this defect affect the operation of the kit?
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QMX won't start after firmware update to 1_02_000
4
Just upgraded from pre-SSB version to 1_02_000 and now the QMX doesn't start again. - Only POP at headphones - No display - No serial port visible at computer - With new upgrade all HW tests worked fine Battery voltage OK (not of course measurable from device). The device worked fine before this upgrade. What should I try to fix this?
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R520 Wrong component value.
9
When testing my newly built QMX+ I was getting high SWR readings while running the diagnostics SWR test. Even when connected to a dummy load the readings were around 2.7 to 1 across all bands. I removed and re-wound T507 (twice) but could not resolve the problem. So I removed T507 for a third time and started to check component values around the bridge circuit. I found that R520, although marked as 68X (49.9 R) , actually measured as 124.5 K. Has anyone else seen this problem. Regards Stephen
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RIT in N1MM
7
I still use TS 480 for the setup of N1MM. When I am in Run and press the up or down key the QMX + changes to RIT .- .030 but cannot be modified then. I have to exit from that on the QMX+. It would have been perfect, if the QMx+ would follow the RIT in run. any suggestions ? -- Martin DK3UW
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I'm in the midst of assembling my 2nd QMX+ and I just busted one of the Shiny Black T37-10 Toroid Cores... DAGNABBIT!!!! So, where's the best place to by only one or two Toroid cores in the US? 73, -Ed, WG5F- Tulsa, OK
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I'll start by saying I think if this as a "nice to have" change: I use a manual antenna tuner and the built in SWR bridge is great for checking the state-of-tune. In a (my) "perfect world", the "Tune SWR" would present a full width, bottom line, bar graph of the VSWR, rather than a single number. It's hard (for me) to spin the tuning knobs looking a flickering numbers. Just a thought. Thank you Hans for producing such a great radio! -- 73, Brent DeWitt, AB1LF Milford, MA
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I need to order some parts from Digikey. I though it would be good to order some backup parts for the QMX+. Besides BS170's what are the components that fail most frequently? Also if you have specific digikey part numbers or names that would be great, ss some of the part names match multiple items.
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QMX CW bandwidth
3
Hi, my QCX has been modified for a passband of around 900Hz and has found more use after the modification. I have a half-built QMX+ and the specs say that cw filter is adjustable from 50-500Hz. Many seasoned cw operators prefer much wider bandwidths for general cw working. I usually listen with around 1,2kHz BW, in tougher conditions the narrower BWs are a blessing. As my QMX+ still awaits to get on the air I want to ask if it?s possible to make the bandwith wider tha 500Hz in CW mode? If that is not the case, I would like to add this to the list of changes in the software of the QMX. 72 Ari OH9VL G-QRP 2068
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Assembled my QMX+ and it's working. I had a couple of issues related to enameled wire not making good connections that were resolved. I know it's working, I've made contacts on several bands successfully, including some decent DX, all on FT8. What bothers me is that the output power seems to jump around wildly. If I go to the diagnostics screen and key the transmitter, the Bias SMPS shows fluctuations in current that correspond to the fluctuations in the output power. The Duty cycle on the Bias SMPS always shows 0%, even as the current jumps around in the red. I suspect I've managed to damage one (or more) of the surface mount semiconductors. At least that's what my reading on the subject would seem to suggest. What I need is a test that can be done with a multi-meter that would shed some light on the problem. I can probably resurrect an oscilloscope if I need it, but I'm hoping someone can lead me to a simple voltage or resistance test that could help isolate the problem. My last problem was related to soldering and enameled wire which was easily resolved. I'm hoping this issue can be resolved without major surgery as well. Thanks in advance for all of the good advice I'm about to receive. Andy WB9YXA
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After a few days of work I completed my new QRP-Labs Xcvr after having built several years ago a Hi Band QDX. It was a real pleasure, no surprise due to an excellent manual and the adjustement and alignment were done today without dificulty. Next step will be to connect it to my Alexloop antenna. To be sure the 6 aft connectors whould slide nicely into the holes of the back plate I had screwed this plate to the lower enclosure and slid the main PCB each time I added a connector to check its position before finishing to solder it. The first difficulties I faced were to fit the LCD module and the front panel PCB to the Front panel of the enclosure : I had to cut slightly the nylon nut close to the potentiometer and I could not put in place the other nylon nut close to the encoder, I just left it near the hole in order to keep the good distance between the LCD board and the front PCB. The Last difficulties happened when I wanted to slid the main PCB inside the enclosure after having put in place the four 12MM spacers which hold the dev kit, the nylon screws below did not slide easily and I had to push quite strongly the PCB inside the enclosure. WELL I'M HAPPY WITH THIS WONDERFUL KIT AND I'M GRATEFUL TO HANS FOR THIS NICE DESIGN.
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SSB Cal problems with QMX (not +)
4
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
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Hello everyone! I think this is my first post in the forums and I wanted it to be a good one. I've been thinking about a good cover for the QMX+ since i pack very compact, but don't want my QMX+ frontpanel to be destroyed. So i came up with the 3D-model below. I'd love if you like the model and come with suggestions. I am open to modify or add versions as needed! https://www.printables.com/model/1300629-qmx-frontcover-stand-and-storage The panels are all dual-sided and can be put on the front or back of the QMX+. Below are some photos:
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