Re: QMX Feature Request - field “tune” mode
Is the "Hardware Tests" -> "Tune SWR" menu item sufficient for your use case? (%voltage settable in "Protection" menu)
On Wed, Feb 28, 2024 at 12:43?PM < w6csn@...> wrote: The SWR metering and protection are features that really make the QMX a field capable radio. However, from several outings now I’m finding that I would like a front panel means to activate a reduced power transmit setting so that I could make adjustments to the antenna tuning while monitoring SWR on the QMX.
Often my antenna is a rather high Q base loaded vertical in which small adjustment to the coil position can result in big swings in feed point impedance. I’ve been using an external SWR/Power meter which presents a 50 ohm load to the QMX while measuring SWR, but this meter is twice as big as the QMX itself and means an extra piece of equipment and coax jumper to carry into the field.
If I could, from the front panel menu enable, a “tune” voltage setting and corresponding tune mode SWR protection threshold, I could leave the external meter at home and dial in the the antenna tuning using just the QMX.
Stretch goal request: an SWR sweep around the operating frequency shown “graphically” on the LCD.
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Re: #qmx high band harmonics
#qmx
Thanks, Hans.? The tinySA has been on my list for a while.? Now I have a good reason to get one!
Eric
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QMX Feature Request - field “tune” mode
The SWR metering and protection are features that really make the QMX a field capable radio. However, from several outings now I’m finding that I would like a front panel means to activate a reduced power transmit setting so that I could make adjustments to the antenna tuning while monitoring SWR on the QMX.
Often my antenna is a rather high Q base loaded vertical in which small adjustment to the coil position can result in big swings in feed point impedance. I’ve been using an external SWR/Power meter which presents a 50 ohm load to the QMX while measuring SWR, but this meter is twice as big as the QMX itself and means an extra piece of equipment and coax jumper to carry into the field.
If I could, from the front panel menu enable, a “tune” voltage setting and corresponding tune mode SWR protection threshold, I could leave the external meter at home and dial in the the antenna tuning using just the QMX.
Stretch goal request: an SWR sweep around the operating frequency shown “graphically” on the LCD.
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Re: Magical smoke out of QDX, two leftmost BS170 very hot
On 28/02/2024 17:54, Volker Kerkhoff wrote: Should changing the 4 BS170 (I have been so cautionary to stock some) fix the issue or should I look at something else before, lest I burn them again straight away? Volker, Remove the BS170s. Test for 5 volts at the gate pads when in transmit. 0 volts receive. If good replace BS170s. Maybe consider a diode across L14, could protect against one failure mode. 73 Alan G4ZFQ
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Re: #qmx high band harmonics
#qmx
Hi Eric
I don't think 'scope FFTs are anywhere near good enough for HF transmitter harmonic testing, and get worse as the frequency goes up. The job needs a real spectrum analyzer. The TinySA is very good value, some 70dB dynamic range if I recall, which is plenty for transmitter testing, and in comparisons I did with my professional SA it was always within a dB. All for somewhere in the $50 ballpark..
73 Hans G0UPL
On Wed, Feb 28, 2024, 9:34?PM Eric W. Hansen < kb1vun@...> wrote: High-band QMX rev2 (2024), 9V version, Firmware 017.? Having fun learning about this radio. LPF cutoffs are good, though LPFs 1 and 2 show stopbands a little high, about –30dB.? I get 4W out on 20m and 17m, less than 3W on 15m, 12m, and 10m.??
I thought I'd take a look at the output spectra, after reading several posts here about harmonics.? I don't have a tinySA, but I do have a 200MHz oscilloscope with good FFT capabilities.? I made the following setup:? QMX --> Dummy load --> 10X probe --> Scope.? The second harmonics on 15m, 12m, and 10m are higher than what I would expect, between 39dB and 42dB below the fundamental.? 20m and 17m are OK, 63dB and 52dB down, respectively.
My understanding is that the push-pull Class D amplifier is effective at suppressing even harmonics, prior to any filtering, so I'd like some ideas about where the high levels might be coming from and what I might be able to do to reduce them.
Thanks!
Eric
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#qmx high band harmonics
#qmx
High-band QMX rev2 (2024), 9V version, Firmware 017.? Having fun learning about this radio. LPF cutoffs are good, though LPFs 1 and 2 show stopbands a little high, about –30dB.? I get 4W out on 20m and 17m, less than 3W on 15m, 12m, and 10m.??
I thought I'd take a look at the output spectra, after reading several posts here about harmonics.? I don't have a tinySA, but I do have a 200MHz oscilloscope with good FFT capabilities.? I made the following setup:? QMX --> Dummy load --> 10X probe --> Scope.? The second harmonics on 15m, 12m, and 10m are higher than what I would expect, between 39dB and 42dB below the fundamental.? 20m and 17m are OK, 63dB and 52dB down, respectively.
My understanding is that the push-pull Class D amplifier is effective at suppressing even harmonics, prior to any filtering, so I'd like some ideas about where the high levels might be coming from and what I might be able to do to reduce them.
Thanks!
Eric
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Correct! In my case I smoked out two of the BS170 and ended up with one heathy BS170. QDX is ?still alive and kicking with that one!:)
3x BS170 is absolutely a better option to distribute output power.
So to summarize here is my QDX QRPp setup:
- removed IC2 - 78M05 from pcb.?
- USB socket 5V pin goes to IC2 - 78M05 5V output pin
- In my case one BS170 is active but 3xBS170 is better.
- No 12V connection.
- The whole rig is powered by PC USB. RF power output around 500 mw to 700 mw band dependent.
The advantage of this setup is I carry only my laptop, ebd fed half wave antenna and ?QDX to Park. No PSU. PC supplies at least two hours of continus fun. My laptop is a microsoft surface laptop.
--
?
73, Barb
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Re: Magical smoke out of QDX, two leftmost BS170 very hot
Ah, yes. more data. This happened on 40m, 7074 KHz. I was transmitting sucessfully right before, couple of POTA QSOs, tuned antenna to SWR 1,2:1 (with NanoVNA)?
73 de EA7KLK Volker
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Magical smoke out of QDX, two leftmost BS170 very hot
Hello,?
'fraid my QDX let out the magic smoke today.?
I had one of these rare moments when it would not transmit after changing band / frequency. I unplugged from both PC and power, plugged pwer back in and it started smoking and stinking immediately. Two leftmost BS17o get very hot and smoke.?
12V build, latest Firmware 1_10, being run at 11,3V - first thing I checked was if my downconvertar had gone nuts - no, it hasn't, it's outputting wonderful 11,3V, under load and without.?
Should changing the 4 BS170 (I have been so cautionary to stock some) fix the issue or should I look at something else before, lest I burn them again straight away??
73 de EA7KLK, Volker
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Low Band Rev1 QMX for sale
Hello, I am offering my fully built low band Rev1 QMX for sale. I am a J-STD soldering instructor and experienced kit builder. My QMX worked fine first time with no issues. I am very happy with the rig but enjoyed building it so much I wanted to build another. I am asking $115 for the radio and enclosure + shipping. Please contact me via my email listed on QRZ under my call N9DXP.
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Just to make sure I understand the theory...? 3x BS-170's @ 5v would still result in the same QRPp power out as Barb's 1x BS-170 @ 5v?
Thanks
Jon n0wl
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Re: Brainstorm question: How to "view" QDX LED status remotely?
Hi Donald.? Quite true about the voltage acquisition timing issues.? One solution is to get the voltage before the limiting resistor for the LED.? Then just buffer (if necessary) and low pass the pulsating voltage.
Glory to God in the highest, and on earth peace, good will toward men. Luke 2:14
On Wednesday, February 28, 2024 at 10:26:31 AM EST, Donald S Brant Jr <dsbrantjr@...> wrote:
Watch the update rate on the meter, as well as the ability to disable the auto range.? With a flashing/pulsing LED the auto ranging might get stuck trying to chase the varying signal.
I have seen this happen, the meter just ranges up and down forever and never settles to a reading.
73, Don N2VGU
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Re: QMX on Inovato Quadra
Awesome, glad to hear this.
How are you finding wsjtx on the Quadra? I got it working before (though with a different radio) but to me it seemed it was barely able to keep up with the decodes and many times was too late causing a reply tx to get skipped till the next frame. I eventually dropped it in favor of the pi 0-2 which has a bump up in horsepower over the Quadra and never misses. But it's been a while and maybe I just need to repave it.
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Re: Faulty Progrock2 - no response to ticket
#progrock2
Thanks, but now the PC no longer opens the Progrock programming page, probably because the pic has broken down and is therefore no longer usable.
73 iw2gg Enrico
I have used numerous ProgRock2's without any problems -- I install them in old receivers and transmitters to replace faulty/drifted crystal-based heterodyne oscillators.? What are you trying to do and what went wrong?? Possibly I can help.
73 - Steve, KW4H
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Re: Brainstorm question: How to "view" QDX LED status remotely?
Watch the update rate on the meter, as well as the ability to disable the auto range.? With a flashing/pulsing LED the auto ranging might get stuck trying to chase the varying signal.
I have seen this happen, the meter just ranges up and down forever and never settles to a reading.
73, Don N2VGU
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Re: Did I fry my QMX SMPS or is it likely worse?
#qmx
Sorry to hear that it’s dead.
No consolation, but it could be worse. I saw an ad a few weeks ago here in UK, for a week old Yaesu FTDX10 that the owner had given 55 Volts… Spares or repairs!
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Re: Did I fry my QMX SMPS or is it likely worse?
#qmx
Thanks for the help everyone. It was a fun build so when budget loosens up a bit I'll give it another go. Maybe by then the QMS will be out.
73 all
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Re: QMX on Inovato Quadra
She lives! It was plain, old, uncomplicated, simple RFI. Clipped two ferrite beads onto the coax, and another two onto the USB cable, et voila, JS8 and WSJT-X work just fine. Thank you to everyone who contributed help and hints, and I apologize...an Extra really should have known better!
Side note to anyone who wants to use JS8Call, reduce minimum samples to 1 from 480. I don't know if the rise and fall thresholds really make a difference, but 10 minutes of playing around this morning before work led the to reduce those numbers from 80 and 60 to 60 and 40, respectively...it seemed to make the radio "hear" what had previously been a blank waterfall. Made a few contacts after that before my paycheck called to me...
73, see you on the air!
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Would Q204 be as sensitive to ESD? Being connected to an external jack (PTT) isn't it sort of hanging out there like an antenna?
--
Tisha, AA4HA
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Re: Brainstorm question: How to "view" QDX LED status remotely?
Thinking about this some more, a Trinket M0 could monitor the voltage of the LED with a GPIO and output it while emulating a USB keyboard. I use trinkets as keyboards all the time. I have a rotary encoder that outputs the AV keyboard codes for volume up and down on my headless pi as an example. They are cheap. Then you need some PC code to read the keyboard and get you the data. It could be done in a web browser to make a status display you could read via VNC.?
--
Colin - K6JTH?
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Barb WB2CBA
Donald S Brant Jr
Tisha Hayes, AA4HA
Colin Kaminski