Re: Observing CW sidebands?
Hello Bogdan
I think there are several possibilities. Some kind of measurement artifact is one. Who knows. But on QMX, CW is transmitted as a single carrier. It isn't produced by modulating a sidetone to RF. The sidetone is produced separately purely for operator convenience, it has no involvement at all in the RF production. I think the main two possibilities if the spurs are really there, would be: - supply noise of some kind. Try a different power supply and see if the spurs are still present. Maybe they are. There could be a possibility of supply noise inside the QMX too, leaking into the PA supply. These spurs you noticed are very low level. So it isn't valid to say oh there's a choke here, an inductor over there, or a capacitor or few here. Capacitors and chokes don't delete?anything absolutely, they just attenuate it to a certain degree.?
- Some kind of spur inherent in the RF synthesis process in the '5351 Synth chip. If that was the case I think it would alter markedly depending on the operating frequency. So moving the operating frequency say, a few kHz, would move the spur. And it would not be in the same place on different bands. These signatures could be used to confirm or reject this possibility.?
Thank you all, I'm happy to hear that there is a general acceptance that they can exist and it's not only a misunderstanding on my part. What could be the reason though? And why such a large difference? i.e. at 1.5 kHz on QMX and +/-100 Hz on the Yaesu. Is there any audio modulation of some sort?
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@Evan I was under the impression that your points about the IF, sampling and downconveting only apply to RX not to TX. I did notice those spurs on the Icom as well, you are right, and I added a footnote comment on the chart. However, I believe I did not see the spurs on the Icom at all at a frequency span of 300 Hz which is a more zoomed in view.
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@Chris I can check if I see these spurs when transmitting via the terminal diagnostic mode and come back with an update tomorrow.
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QMX CW keyer & message memory glitch.
I have a pre-built QMX low band that I received a couple months ago. I made a few contacts from my home QTH before taking it out to do a POTA activation. Every worked perfect at home and the memory message also worked as designed.
When I was in the field, the first few contacts went well. Then in the middle of a contact my keyer (VK3IL pressure paddle), just quit working. Thinking it was the paddle, I unplugged it and plugged in my SP4 paddle and it would not work either.
Next I powered cycled the QMX and tried the keyer again and it was working.
After the power cycle, I tried using my memory message and it would loop the message nonstop until I intervened. I powered off the QMX, disconnected/ reconnected the battery, and powered the QMX back on. The memory message continued to loop nonstop. At
this point I was done trying to troubleshoot it in the field and just put it away and used my FT-891 to finish the activation.
Has anyone had a similar experience?
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QMX CW keyer & message memory glitch
I have a pre-built QMX low band that I received a couple months ago. I made a few contacts from my home QTH before taking it out to do a POTA activation. Every worked perfect at home and the memory message also worked as designed.
?
When I was in the field, the first few contacts went well. Then in the middle of a contact my keyer (VK3IL pressure paddle), just quit working. Thinking it was the paddle, I unplugged it and plugged in my SP4 paddle and it would not work either. Next I powered cycled the QMX and tried the keyer again and it was working.
After the power cycle, I tried using my memory message and it would loop the message nonstop until I intervened. I powered off the QMX, disconnected/ reconnected the battery, and powered the QMX back on. The memory message continued to loop nonstop. At this point I was done trying to troubleshoot it in the field and just put it away and used my FT-891 to finish the activation.
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Has anyone had a similar experience?
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Jerry, my LiFePo4 cells have already a battery management system. About the voltage, I guess I will power the QMX+ with 9V since the 4xLiFePo4 give between 14.2V fully charged and 12V discharged, 9V would be nice. Thanks for the idea to find the connections inside the box and attache the cells to the enclosure.
73 - Pierre - FK8IH
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Pierre, as you probably know, you probably want to include a battery
management system?to balance cells and avoid over-discharging or over-charging.
LiFePO4 is not as forgiving of overcharging as some chemistries.
This means can't overcharge some cells in a string of four to restore balance
while the remaining cells not yet fully charged catch up.
Do a web search for "4S LiFePO4 BMS".
?
Alternately, you could pop the four individual cells out of the battery pack
and put them into a commercial battery charger.
?
Jerry, KE7ER
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Re: Large blank QCX+/QMX+ style enclosures
On Mon, Nov 11, 2024 at 03:38 AM, Hans Summers wrote:
also have small size blank front/rear panels which would suit a blank version of the QDX, QCX-mini, QMX and 50W PA enclosures. However, due to my own mistake, these items were not immediately assigned an internal QRP Labs stock code and have therefore?misplaced themselves, hiding very well somewhere in our stockroom, and my colleague has not yet managed to locate them.?
Hans, were these ever located and/or listed??
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-Nate
N8BTR
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You can make the necessary connections directly to the dev board, by installing standard male and female connectors to the QMX+ board.? Hans put footprints on the QMX+ for audio, all voltage busses, etc.? Sardar used these for his ABS (ATU-Battery-Speaker) design that several of us built.
Stan
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Pierre,
?
Sounds like four 26650 cells, side by side.
Could work out well.
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I see slightly over 31mm above the dev board to the inside of the top cover, almost 32mm.
Mounting the LiFePO4's to the dev board should work fine.
?
You might consider attaching the LiFePO4's to the top cover,
keeping weight off the main QMX board in case of a sudden shock.
?
Could also mount stuff to a new board that slides into the top rails,?
just like the main board slides into the bottom rails.
Your LiFePO4's would fit, but perhaps touch the top of some toroids.
Would definitely fit if you cut holes in the new board that the LiFePO4's sink down into.
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Jerry, KE7ER
?
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On Wed, Mar 12, 2025 at 05:02 PM, Pierre - FK8IH wrote:
What is the usable height above the dev board once installed in the QMX+ standard enclosure? I plan to build a complete QMX+ and use the dev board to install:
- a set of four LiFePo4 batteries (105x65x26mm);
- a DC-DC 12V 24V to 9V 4A 36W Converter DC Voltage Reduction and Stabilization Waterproof Voltage Reduction Module Suitable for Various 9V Equipment to generate a stabilized 9V voltage to power the QMX+. (https://www.amazon.com/Converter-Reduction-stabilization-Waterproof-Equipment/dp/B0C179FLV3/ref=sr_1_1_sspa?dib=eyJ2IjoiMSJ9.xqzM 2Hf03dOzy2nwqMax7Qf4sJEp_zLLnwUGQY-uK66l12Hz3NDHnJAtg5CKDuO1Gv6cJpWSPdPM--7-OKOI9LueaAjCLUhr_nMp32NVSTGR8H4bASlSvuoWmzrtD9MQnpgJuaW 9RiEoLtvPrcrjc3o4umJlOuxhySJ_seF1oQNPFv86sfw_SiUxu983cpfXdj5typRCWbYQXZzjHi4Md0Snoxj94pgdX4_LB6sVs_g.-juE80eVb5RbLMEfZu7Nk-jkFn7Fu tPixjGIfHq44EE&dib_tag=se&keywords=12v%2Bto%2B9v%2Bdc%2Bconverter&qid=1734408845&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&th=1);
- an audio amp and speaker.
Connections would be made through additional connectors soldered to the dev board aft line and accessible through holes drilled in the rear face of the enclosure.
73 - Pierre - FK8IH
?
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What is the usable height above the dev board once installed in the QMX+ standard enclosure? I plan to build a complete QMX+ and use the dev board to install:
- a set of four LiFePo4 batteries (105x65x26mm);
- a DC-DC 12V 24V to 9V 4A 36W Converter DC Voltage Reduction and Stabilization Waterproof Voltage Reduction Module Suitable for Various 9V Equipment to generate a stabilized 9V voltage to power the QMX+. (https://www.amazon.com/Converter-Reduction-stabilization-Waterproof-Equipment/dp/B0C179FLV3/ref=sr_1_1_sspa?dib=eyJ2IjoiMSJ9.xqzM 2Hf03dOzy2nwqMax7Qf4sJEp_zLLnwUGQY-uK66l12Hz3NDHnJAtg5CKDuO1Gv6cJpWSPdPM--7-OKOI9LueaAjCLUhr_nMp32NVSTGR8H4bASlSvuoWmzrtD9MQnpgJuaW 9RiEoLtvPrcrjc3o4umJlOuxhySJ_seF1oQNPFv86sfw_SiUxu983cpfXdj5typRCWbYQXZzjHi4Md0Snoxj94pgdX4_LB6sVs_g.-juE80eVb5RbLMEfZu7Nk-jkFn7Fu tPixjGIfHq44EE&dib_tag=se&keywords=12v%2Bto%2B9v%2Bdc%2Bconverter&qid=1734408845&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&th=1);
- an audio amp and speaker.
Connections would be made through additional connectors soldered to the dev board aft line and accessible through holes drilled in the rear face of the enclosure.
73 - Pierre - FK8IH
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Hello,
Has anyone tried using a 11.1V battery on the QMX?? Fully charged the batter has12.7 volts.??
?
Thank you,
Brian K?BWH?
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Re: QMX VSWR indication
#qmx
I hope it is ok to revive an old thread, but I just stumbled upon it. Replacing the SS14 with 2 BAT54 in parallel solves this issue. See: /g/QRPLabs/message/139720Power levels read the same as before. Shielding the 1-turn windings had no effect. Gottfried oe1ira
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Re: Determine 9v/12v of QDX?
And the current it pulls, as mentioned. About 1A @ 9V for a 9V build. Would be less, like 0.7-0.75A on a 12V build, I believe.
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-Nate
N8BTR
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Down to $90 here now.
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-Nate
N8BTR?
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On Sat, Mar 8, 2025 at 02:27 PM, Nate Reik wrote:
$100 shipped within the lower 48. (through this group... priced a bit higher on QRZ)?
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Re: Observing CW sidebands?
Thank you all, I'm happy to hear that there is a general acceptance that they can exist and it's not only a misunderstanding on my part. What could be the reason though? And why such a large difference? i.e. at 1.5 kHz on QMX and +/-100 Hz on the Yaesu. Is there any audio modulation of some sort?
?
@Evan I was under the impression that your points about the IF, sampling and downconveting only apply to RX not to TX. I did notice those spurs on the Icom as well, you are right, and I added a footnote comment on the chart. However, I believe I did not see the spurs on the Icom at all at a frequency span of 300 Hz which is a more zoomed in view.
?
@Chris I can check if I see these spurs when transmitting via the terminal diagnostic mode and come back with an update tomorrow.
?
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Re: Determine 9v/12v of QDX?
I bought a used QMX, and the seller forgot if it was a 9V or 12V, he had built so many and lost track.? I opened it, took a picture of T501 from the side with my phone, and enlarged the picture.? Made it easy to count the number of turns and verify it was a 9V.??
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Then I hooked it up to a 9V source and got 4-5 Watts out at about 1 Amp into a dummy load, which confirmed 9V behavior.
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73
Mike N9OHW
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George,
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The NaP3 has good CAT control with QMX on CW, DIGI, and SAM modes.
The CW filters work very well with adjustable bandwidth from 1.0 kHz down to 50 Hz.
The NaP3 CAT Control tuning works in CWL, CWU, SAM, DIGL and DIGU modes.
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73, Carol KP4MD
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Re: Determine 9v/12v of QDX?
Guess I could do that...didn't process that it would work at 9v with the 12v winding just be low output. I'll have to figure out a way to hook it to a bench supply because I don't have another 9v source handy but that's much easier in a way XD
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Thanks for the suggestion Jim!
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Re: Determine 9v/12v of QDX?
Just a WAG here, and not a technical one - why not power it up with 9v and use PuTTY and a dummy load to see how much power it generates. Seems like if it was wound for 9v you should get full 4-5 watts. If wound for 12v, much less output.
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Show quoted text
On Mar 12, 2025, at 2:43?PM, CJ - WW0CJ via groups.io <cjtheham@...> wrote:
? I have an old QDX I started building years ago (Rev 3) and I wound the PA transformer...and promptly forgot if I wound it for 12v or 9v.
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I'm looking to work on finishing it now and reading the conventional winding docs is hurting my head, no idea how I managed to do it the first time. Is there an easy way to spot and tell if it's wired for 9v before I plug it up to a battery and fry it? Can I tell just off the number of turns on each side or do I have to do something else?
?
Apologies for the semi-simple question: brand new to kit builds and trying to get the old stuff I started and never finished on the air XD
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73,
CJ WW0CJ
-- Jim / K7TXA
Eagle, ID
SKCC 10447T
BUG 301
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I have an old QDX I started building years ago (Rev 3) and I wound the PA transformer...and promptly forgot if I wound it for 12v or 9v.
?
I'm looking to work on finishing it now and reading the conventional winding docs is hurting my head, no idea how I managed to do it the first time. Is there an easy way to spot and tell if it's wired for 9v before I plug it up to a battery and fry it? Can I tell just off the number of turns on each side or do I have to do something else?
?
Apologies for the semi-simple question: brand new to kit builds and trying to get the old stuff I started and never finished on the air XD
?
73,
CJ WW0CJ
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Re: PIN diode bias current unstable
#qmx
On Wed, Mar 12, 2025 at 05:07 PM, Stan Dye wrote:
FWIW, ?I just finished assembly of a new v3 QMX+, and it is working perfectly. ? So if there is a component issue, it is not on all units.
So far, all my v3 builds have had this problem. All my v2 builds never.
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Bob Peterson
Pierre - FK8IH
Carol KP4MD
CJ - WW0CJ