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First attempt at WSJT-X failed

 

QMX
1_00_027 firmware
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WSJT-X would not work with the choice of the QMX as the transceiver. Kenwood 480 did work.
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CAT button works.
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I did select the QMX sound input and output in Ubuntu on my Dell.
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WSJT-X was set to full power as was the Ubuntu sound output.
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On TX there was a full bar under the A in the QMX display.
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The QMX was set to digital mode.
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I called CQ on 20 m, which was active at the time and also tried to answer CQs to no avail. I was using my EFHW in my shack. I have worked 131 countries with it and a Icom 7300.
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I thought maybe I might have blown my finals in some way.
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I connected to the QMX with Putty and went to the Hardware Test section.
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With supply voltage of 11.3V I tested every band by pressing the T key on my keyboard for TX and have the following results. A dummy load was attached.
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15m? ? ?5.2w
17m? ? ?4.2w
20m? ? ? 4.7w
30m? ? ? 4.1w
40m? ? ? 4.4w
60m? ? ? ?5.1w
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Since I have output on all bands with this test, I assume I didn't blow the finals. The QMX seems okay and I should just keep trying with WSJT-X.
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I do have a question about the display above. The status of the 3.3v SMPS says "SMPS" while the status of the 5v SMPS says "OK."
Should the 3.3v status also say "OK?"
 

On Mon, Apr 14, 2025 at 10:38 AM, Jim Brown wrote:
Should the 3.3v status also say "OK?"
No, it is fine.? When in linear mode it says 'LINEAR'.
 

Regarding failure to make contacts in WSTJ-X:
From your notes, it seems you have things set correctly for WSJT-X to transmit (full bar under the 'A') and it is decoding fine.
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So a few things to check:
1) Is QMX in practice mode?? (P in the display after the frequency) CW practice mode kills TX in all modes.
2) Are you getting SWR protect? (S in the display after the frequency) - that would kill TX
3) VFO mode: make sure you are set to ONLY VFO-A or ONLY VFO-B.? Don't try split mode; it confuses WSJT-X, and you may not be transmitting on the frequency you expect.? Make sure WSJT-X Radio 'mode' is set to 'none' and 'split operation' is set to 'none'.? And manually set DIGI mode and one VFO (not split) on the QMX.
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Stan KC7XE?

 

Stan,
There was an S after the frequency at one point but I have eliminated it.? I have disabled the B and Split VFO. Thank you for your suggestions!
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I removed a Heathkit Power Meter between the antenna tuner (LDG AT100proII). The antenna tuner was getting its power from my IC-7300 and there was a control cable from the 7300 as well. I disconnected the control cable. The auto tune of the antenna tuner can be activated by as little as 1w.?
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I tried to make WSJT-X contacts again. First contact was Nova Scotia and a second Georgia on 20m. So I guess I have things working now.
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I do have a question on the attached screenshot.
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The WSJT-X Rx max is about 50db. Normally I like to have that at about 70 db.
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Is there a setting on the QMX that I can increase that?
 

After making several contacts on WSJT-X, the S appeared after the frequency.
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I select Hardware tests/ Tune SWR and I get an SWR of 1.00 but when I transmit in WSJT-X, the S appears after the frequency and I get no output.
 

On Mon, Apr 14, 2025 at 01:59 PM, Jim Brown wrote:
The WSJT-X Rx max is about 50db. Normally I like to have that at about 70 db.
Is there a setting on the QMX that I can increase that?
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Yes, you can change it using the audio level control in the Band configuration screen (via the terminal interface). It is set on a per-band basis.
But I don't think you should.? WSJT-X authors recommend 60 or below, and raising it won't improve your receive performance.
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Stan KC7XE.
 

On Mon, Apr 14, 2025 at 02:30 PM, Jim Brown wrote:
After making several contacts on WSJT-X, the S appeared after the frequency.
I select Hardware tests/ Tune SWR and I get an SWR of 1.00 but when I transmit in WSJT-X, the S appears after the frequency and I get no output.
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This is likely due to your use of the antenna tuner while transmitting at full power.?
When that ATU switches its relays to find a match, it presents momentary 'high SWR' to the QMX, causing it to go into SWR protect.? [Depending on your ATU, this may also happen even if it doesn't 'tune', when it switches to its tune memory settings for the current frequency.]
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What I recommend doing is disabling the 'auto' on your ATU during normal operation, and when you change bands/frequencies and need to tune again, turn back on the 'auto', and use the QMX Hardware tests -> Tune SWR feature to give a reduced-power signal to activate the tuner auto-tune.? The SWR protect is automatically disabled in this mode, and the reduced power will remove risk of blowing your finals due to high SWR.? The default setting is 50% (voltage), 1/4 power.?? If this is too low for your tuner, turn it higher, maybe up to 75% (Protection menu -> Tune %).? This is how the QMX was designed to adjust tuning.
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Some others don't like to do that, so they disable SWR protection, or set its threshold very high, so it won't trip when the ATU switches.? But do this at your own risk: it will likely work fine for a good while - but the momentary high SWR events may eventually wear down your finals and blow them.? There have been a few posts in this forum in the past about blown finals due to ATU switching.
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Or just use an antenna that already has an SWR of about 1.7 or less - and don't use a tuner.? There is almost no functional difference in tuning an SWR of 1.7 down to 1.0 vs. not using a tuner.? The small loss in the tuner inductors is about the same penalty as a bit higher SWR.
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Stan KC7XE
 

Stan,
Thank you so much for your detailed reply. You are an important part of my education.
Jim W0RLD
 

On 14/04/2025 21:40, Stan Dye via groups.io wrote:
But I don't think you should.? WSJT-X authors recommend 60 or below, and raising it won't improve your receive performance.
Stan,

The current thinking is to run the ADC as high as possible without it actually being overloaded. (The bar goes red.)

I have the feeling that this is theoretical, I've not seen any research proving more decodes are made. (Not an easy task given the wide variations in band conditions.)

I'm fairly certain the difference is at best marginal.

73 Alan G4ZFQ
 

Just a quick comment: If You use Icom ATU such as AH-4, the tuner has a buildt-in attenuator that attenuates the RF signal something like 15 dB while?tuning. Hence?showing approx 50 Ohm impedance even while tuning.? The tuner is specified to have a 5-15w input signal, but in my experience it works also from 2-3w.?

A simple interface for starting the tune process with Icom ATUs can be buildt like this:?
image.png


Regards, Jonas


Den m?n 14 apr. 2025 kl 23:59 skrev Stan Dye via <standye=[email protected]>:

This is likely due to your use of the antenna tuner while transmitting at full power.?
When that ATU switches its relays to find a match, it presents momentary 'high SWR' to the QMX, causing it to go into SWR protect.? [Depending on your ATU, this may also happen even if it doesn't 'tune', when it switches to its tune memory settings for the current frequency.]
?
What I recommend doing is disabling the 'auto' on your ATU during normal operation, and when you change bands/frequencies and need to tune again, turn back on the 'auto', and use the QMX Hardware tests -> Tune SWR feature to give a reduced-power signal to activate the tuner auto-tune.? The SWR protect is automatically disabled in this mode, and the reduced power will remove risk of blowing your finals due to high SWR.? The default setting is 50% (voltage), 1/4 power.?? If this is too low for your tuner, turn it higher, maybe up to 75% (Protection menu -> Tune %).? This is how the QMX was designed to adjust tuning.
?
Some others don't like to do that, so they disable SWR protection, or set its threshold very high, so it won't trip when the ATU switches.? But do this at your own risk: it will likely work fine for a good while - but the momentary high SWR events may eventually wear down your finals and blow them.? There have been a few posts in this forum in the past about blown finals due to ATU switching.
?
Or just use an antenna that already has an SWR of about 1.7 or less - and don't use a tuner.? There is almost no functional difference in tuning an SWR of 1.7 down to 1.0 vs. not using a tuner.? The small loss in the tuner inductors is about the same penalty as a bit higher SWR.
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