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As others have reported, I have lost half of the previous output power on my QMX+ after running the calibration.?
I am beginning to suspect that I lost one or more of the transistors in the final power amplifier.? I will do some more testing to verify.? I ordered some replacement BS170s just in case.
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The calibration routine appears to stress the finals and sort out the weak from the strong MOSFETs.
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Steve KA0SM
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I noticed when I have EQ turned on, that I get choppy audio.? This happens when "Use EQ" is set to yes.? It persists while I am using the terminal or when I am out of the terminal or even when usb is disconnected completely, and after a reboot of the transceiver.? I am not sure if it is setting related or just an issue with the EQ functionality.
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With those settings turned on, you will be getting about 20dB lower of a signal from your mic to the audio path (compared to when the setting is turned off) - so it may be reacting with other downstream settings that require a minimum amplitude.
Crank up that 'global gain' parameter so the output of the EQ when 'on' will be similar to when 'off', and the choppiness should go away.
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On Mon, Mar 24, 2025 at 06:31 PM, Stan Dye wrote:
With those settings turned on, you will be getting about 20dB lower of a signal from your mic to the audio path (compared to when the setting is turned off) - so it may be reacting with other downstream settings that require a minimum amplitude.
Crank up that 'global gain' parameter so the output of the EQ when 'on' will be similar to when 'off', and the choppiness should go away.
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What is the factory default?? I must have fat fingered something.
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On Sat, Mar 22, 2025 at 11:37 PM, <adam@...> wrote:
Hans,
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I have been having a similar issues on 20m. (20M to 10M QMX). When first running calibration, I used "R" run mode to do everything via the console.? On both 20m and 11m the Phase Error vs DAC plots finished very quickly and looked strange.? SSB effectively did not work and was just distortion on Tx.?? I re-ran BOTH Phase and USB for 20m using "O" once mode and while the Phase plot still looks strange it did change. Tx improved and I have been making contacts.?? The Phase plot changed when I ran it in "O" mode.?
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Adam,? I had a similar wierd short plot on 20m (see earlier post on earlier beta thread with audio clips) which resulted in distorted transmit audio on 20m only (the other bands were good).? I found that going into the band configuration and changing the 20m centre frequency small amounts drastically changed the plot.? I settled on a 20m centre frequency of 14300000 which produced a smooth descending plot although not with as many points as say, 17m.
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Cheers,
Glenn VK3YY.
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I forgot to add that with the changed centre frequency and smoother plot on 20m, the transmitted audio sounds as good as the other bands now.
Cheers,
Glenn VK3YY.
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I'm still getting a weird phase error plot on 80m. It stops at 36%.? U shaped with near right angles at the corners. I tried adjusting the band config parameters, moving the centre Freq around. Still weird.? What band config settings are people using that gets a normal / full plot?
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73
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Simon?
VK3ELH?
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Jack,
? I have been having a similar issue, and found I got wider. smoother curves on 80 meters with my QMX+ if I configured the band edges closer to the actual legal band edged, then set the center frequency near the center of that, then used O to walk through each step of configuration. However, I don't know it the mathematical result is better because of that, because I didn't notice much real difference in the final SSB output, which is what this configuration is measuring. I lack proper test equipment for that and can only judge by ear. I think, at least in my case, I'm going to have to stop messing around and let people with the proper test equipment do the measurements and come up with conclusions.?
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73, Dan - W2DLC
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I had the same thing happen... QMX+ is on the bench with the BS170's removed, and one of them indeed tested bad. While waiting on my replacement BS170's I am carefully cleaning out the holes. I really don't want to deal with this again.
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Would reducing the operating voltage during the calibration help prevent it again? Does the calibration depend on the actual voltage used to be accurate. I normally operate at 12V with a low dropout precision regulator. If I calibrated at, say, 9V, would the calibration be accurate for use at the normal 12V?
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Just thinking out loud...trying hard not to do a second transistor transplant. Not sure the patient would survive lol...
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73,
Joel W9JFK
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Joel,
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I calibrated mine at 11.1 volts, battery voltage dropped with 3 diodes in series and it all went well. I continue to operate at that voltage and the output is slightly lower than it was at 12 volts, but it is not a significant difference. I am not worried about the last few mW.
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73,
Jim AC9YY
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IIRC, Hans already has stated that the calibration must be done at full power, which makes sense as it is a way of measuring, and compensating for, the non-linearity inherent in the final amplifier design. That would necessarily mean the calibration must be done at operating voltage. Hans has also suggested that the calibration isn't necessary, as he has included a set of constants that are pretty good in all of the cases he has tried, but that calibration will definitely improve the radio's performance.... Which for most hams means it is, well, essential... Hans has also stated that his QMX finals easily pass the engineer's calibrated finger test, which would seem to lend some credence to those whose measurements have shown the BS170 has a too low Vds to safely operate on the lower bands. Not to disparage those making such claims, but "measuring" is "changing", in the RF world.... but you gotta start somewhere. Transistor manufacture is still a variable enough process that most transistors manufactured will exceed the standards shown on the data sheets. Alas, most is not all. -Chuck Harris, WA3UQV On Tue, 25 Mar 2025 06:57:02 -0700 "Joel W9JFK via groups.io" <w9jfk@...> wrote: I had the same thing happen... QMX+ is on the bench with the BS170's
removed, and one of them indeed tested bad. While waiting on my
replacement BS170's I am carefully cleaning out the holes. I really
don't want to deal with this again.
Would reducing the operating voltage during the calibration help
prevent it again? Does the calibration depend on the actual voltage
used to be accurate. I normally operate at 12V with a low dropout
precision regulator. If I calibrated at, say, 9V, would the
calibration be accurate for use at the normal 12V?
Just thinking out loud...trying hard not to do a second transistor
transplant. Not sure the patient would survive lol...
73,
Joel W9JFK
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Rather than use the microphone input I have been running Fldigi into the USB and having some nice QSOs on Olivia. Olivia has amplitude modulation of the envelope (unlike wspr or ft8) due to how the individual tones are sent. It is not just a simple FM MFSK signal and really needs proper SSB modulation to work as designed. Looking at the time domain on my scope the envelope is just as it should be with fluctuations in amplitude during tone transitions.?
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When I run calibration of either the QMX and QMX+ using Putty I get a lot of flat lines and incomplete graphs. It does feel like the process is working as it should. I suggest adding some hand-holding messages to assure the user of proper completion. Based on comments above I will try doing the calibration stand alone.
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I have monitored the transmit signal using an SDRPlay RSP1A and Steve Andrews' free RSP Spectrum analyzer software. I used that to check both two-tone IMD and also unwanted sidebands on an Olivia signal. When I look at the two-tone IMD spectrum I see improvement with the phase compensation ON on some bands and improvement with it OFF on others. For now I am leaving it off and will wait to see how things develop. Amplitude compensation has only minor effect as expected. Unwanted energy from the transmitter is at acceptable levels for now.
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It's worth noting that using the same measurement methods I can see substantial improvement (~ 15 db) when using the Pure Signal feature of the Hermes Lite 2 through a linear amplifier so I know this technique can show a good effect.
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For right now I am thrilled to have SSB mode so I can transmit proper Olivia and will take the QMX with me to the UK for portable ops. Down the road it would be nice to set receiver bandwidth as with cw but for typical digital signal bandwidths.
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Thanks for all the hard work, Hans!
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Thank you for kindly answering my question... I truly appreciate it. I suppose I could have known that Hans already addressed this, but I admit that I have been unable to keep up with messages.
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I will run the calibration at the operating voltage. Might steal a few tenths though LOL...
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But I truly appreciate the information, fellowship, and helpfulness on this forum.
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73 & God bless,
Joel W9JFK
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No point to clean out the holes when replacing the BS170's, about all that does is damage the board with all the heat.
Just clip the new leads short and lay them flat across the top of the holes, solder them down.
Makes it easier to remove them next time you blow the finals.
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Jerry, KE7ER
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Those are plated through holes full of solder, and there is no chance the new BS170's are going to fall off the board.
What's the point of pushing the new leads through the holes?
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On Tue, Mar 25, 2025 at 07:35 AM, Chuck Harris wrote:
While waiting on my
replacement BS170's I am carefully cleaning out the holes. I really
don't want to deal with this again.
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On Tue, Mar 25, 2025 at 06:57 AM, Joel W9JFK wrote:
trying hard not to do a second transistor transplant. Not sure the patient would survive
Joel, when replacing the transistors 'next time' if there is one: just cut off the body of the bad transistors, leaving most of their lead-length in place and soldered to the board.? Then lay the new transistor in place, on top of the still-soldered leads, and solder the new transitor to the old leads.? Much easier, in my opinion, that cleaning out those vias.
Stan.
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Dear all.
on my QMX, Rev2, 80m-20m, the diagrams for the ‘phase error vs DAC’ do not correspond to Hans' example. I have performed a factory reset. I have adjusted the band configuration: start, end and centre. See screenshot. I have disabled ‘20/80 BPF TXswap’ in the menu.
I would be grateful if someone could post the band configuration for a QMX 80m-20m as an example in this forum.
Stephan, DD6DO
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Hi Guys!
I managed to install the 1_01_003 SSB Beta on the weekend and
just took a few screenshots to provide another data-point for a
High-Band QMX.
Calibration was ok, but 20m and 10m look a bit suspicious. I still
need to build / adapt an external microphone.
All snapshots of my initial build and the SSB calibration on my
Google drive:
If the link gets filtered out, i give you the 20m picture inline
here:
10m looks similar
17, 15, 12, 11m more normal, as there is a dip with a clear
minimum visible in the graph.
No idea if my results are good, bad, normal, abnormal. Just
providing another set of measurements for you and Hans.
73 de Tobias DL3MHT
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I wouldn't worry to much. Hans wrote regarding the calibration "The results are markedly different by band, this is normal. " and "Some phase error measurements do have weird glitches."
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73 Ludwig
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When I use my Hermes Lite 2 or a Tiny SA it appears that my audio goes way beyond 3 KHz on USB for example both above and below my center frequency. However checking on a remote WebSDR I see what looks like a clean well defined SSB/USB signal and all my audio reports have been good.
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73,
Jim AC9YY
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Glenn S
Daniel Conklin
Jim AJ8S
DD6DO
