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New QMX+ with a couple of issues? #160m #bpf #QMXplus

 

I have just finished building a Rev 2 QMX+. It was a fun build and all went smoothly ... with a couple of minor exceptions.
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1) For some reason, PuTTY refused to work on my Win10 desktop (it had worked in the past). It recognized the QMX on a serial port but then it just "hung". Luckily, my Win11 laptop worked perfectly and I moved on to the diagnostics.
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2) Power out ranged from a high of 5.0 watts on 160 to 2.3W on 6 metres. (This is quite acceptable for sure.)
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3) The biggest problem was the image rejection on 160M. Here's a table of the results:
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Band????? Image
160????????? -3.8 (no the decimal point is correct!)
? 80????????? -37
? 60????????? -41
? 40????????? -43
? 30????????? -46
? 20????????? -50
? 17????????? -58
? 15????????? -36
? 12????????? -35
? 10 ? ?????? -38
??? 6????????? -20
?
In an effort to resolve the 160M image problem I removed L401 and rewound it! Unfortunately nothing changed. I also went into the band configuration and changed the BPF from 0 to 1 just to see what happened. Nothing changed? So it looks like BPF 0 is not there for some reason?
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The chances of me using this rig on 160 with 2.3W are fairly remote, however, it would be nice to get the image numbers to a more reasonable level.
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Thoughts appreciated. Thanks!
--
73, Rick
VE7TK

Website:

Re: Clear SWR Protection "S" through the USB port?

 

FANTASTIC!
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It worked as advertised.
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Many THANKS!
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Sam,AC4OW
Re: QDX: Troubleshooting high output power

 

I should add that I built this for 9V per the rev 3 assembly manual (not the transformer manual).
I am still being amazed by the QMX I recently built

 

I activated #pota us-10658 with the #QMX mid-band I built this morning (5 watts). It was pretty windy so I didn't record any video since I forgot my wind sock. I started with 30 meters and moved through 40, 20, 60, 17 and 15. I got QSOs on all but one band (60). ?I got one or two ?on 30, 40 and 17, most were on 20 and 15. I managed a DX QSO with #sweden SM3NRY on 15 meters (21.062). The wind started getting so bad that my Chameleon #vertical was bowing. I got a total of 34 QSOs before I went QRT.
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Re: Clear SWR Protection "S" through the USB port?

 

THANKS!

Thanks,

Sam Hanie


623-219-8130


On Sun, Oct 13, 2024 at 11:05?AM Chris KB1NLW via <chrisrey1=[email protected]> wrote:
Sam
Be extremely careful using the auto tuner.? When it is seeking a match SWR can transiently exceed 10:1.? This causes high voltage at the BS170 PA transistors that does substantially exceed the manufacturers rating.? I recently recorded these transients at the PA transistors and posted the results.?
It is absolutely necessary to tune with an ATU a no more than 50% PA voltage or use an attenuator between the ATU and QMX while tuning (I use a QRPoMeter).
?
Notes:? From my testing it is high PA voltage that kills the BS170s and not temperature.?
? ? ? ? ? ? Also the ATU transient spikes are worse at 160m and 80m.
? ? ? ? ? ? A also operate the QMX remotely and am very careful to ensure I don't get ATU spikes.
?
Re: Clear SWR Protection "S" through the USB port?

 

Many THANKS!

Thanks,

Sam Hanie


623-219-8130


On Sun, Oct 13, 2024 at 12:27?PM Chris KB1NLW via <chrisrey1=[email protected]> wrote:
Can do it remotely using the terminal mode.? I just tried the following steps - may not need all of the steps:
  1. Exit WSJT-X?
  2. Enter terminal mode
  3. Select: Hardware-test/SWR-Sweep ( Should be crazy data since no RF)
  4. Select: Configurate/Protection/SWR (select Disable)
  5. Select: Hardware-test/SWR-Sweep ( Should be good data since there is RF)
  6. Select: Configurate/Protection/SWR (select Enable)
  7. Exit terminal
  8. Enter WSJT-X?
  9. Use PSK reporter to verify transmit.
It would be good to reset the SWR protection on a band change.
QDX: Troubleshooting high output power

 

Hello,
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Was hoping I could get some help on how to troubleshoot my QDX.? I looked through the list, but was having trouble finding quite the right thing.
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It is a QDX rev 3.? I updated it to the latest firmware, and then wanted to test the transmission before using.??
I have it powered by a benchtop power supply, limiting it to 9 volts and 1.3 Amps.
I have a dummy load fitted and am monitoring the signal across it with my oscilloscope.
Not transmitting, it is drawing 144mA at 9V according to my supply when connected to USB.
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I went into the console application, selected "Transmitter test", and pressed "t" to transmit (on 40M)
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On the oscilloscope I saw 40V peak-to-peak for about a second before it stopped transmitting.
The LED turns off while transmitting.? The QDX was still on and I was still connected to the terminal.
I can't quite catch what the power supply is doing (as it is happening too fast), but it *looks* like it is going up to about 850mA and not going into limiting.
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Similar on 60M and 80Mt, though slightly higher power.
On 20M/30M, the LED goes momentarily and I see the power supply current start to go up, but never see a signal on the scope.
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Other things I noticed
* The RF frequency sweep shows the pass bands being way off on all frequencies - the pass band looks way above where it should be (ie, 20M looks to peak a little under 15MHz, 40M is peaking around 8.5MHz, etc)
* Audio filter sweep looked fine.
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Could anyone help suggest what I might have done wrong and what steps I should follow in troubleshooting?
Thank you!
-Ben
?
Re: Clear SWR Protection "S" through the USB port?

 

Can do it remotely using the terminal mode.? I just tried the following steps - may not need all of the steps:
  1. Exit WSJT-X?
  2. Enter terminal mode
  3. Select: Hardware-test/SWR-Sweep ( Should be crazy data since no RF)
  4. Select: Configurate/Protection/SWR (select Disable)
  5. Select: Hardware-test/SWR-Sweep ( Should be good data since there is RF)
  6. Select: Configurate/Protection/SWR (select Enable)
  7. Exit terminal
  8. Enter WSJT-X?
  9. Use PSK reporter to verify transmit.
It would be good to reset the SWR protection on a band change.
Re: DX on my QMX-PLUS !

 

That was on Ten meters FT8. Ten is wide-open today !
72,
Bill, N4QA/QRP
Re: QMX+ Success, with One Nit Easily Resolved

 

Yeah, some lessons come the hard way. Like I said in my original post, I know better, frankly, but there you go!?
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Just had another really fun POTA activation yesterday with it, and am looking forward to lots more to come.
Re: Clear SWR Protection "S" through the USB port?

 

On Sun, Oct 13, 2024 at 06:11 AM, Sam Hanie wrote:
with the rig in another room, I would like to be able to reset the "S" remotely.
Great suggestion!? The "S" is a showstopper for remote operation.? Perhaps there will be a way to do it once Hans release his BASIC programmer interface.
?
73, Mike KK7ER
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Re: Clear SWR Protection "S" through the USB port?

 

Sam
Be extremely careful using the auto tuner.? When it is seeking a match SWR can transiently exceed 10:1.? This causes high voltage at the BS170 PA transistors that does substantially exceed the manufacturers rating.? I recently recorded these transients at the PA transistors and posted the results.?
It is absolutely necessary to tune with an ATU a no more than 50% PA voltage or use an attenuator between the ATU and QMX while tuning (I use a QRPoMeter).
?
Notes:? From my testing it is high PA voltage that kills the BS170s and not temperature.?
? ? ? ? ? ? Also the ATU transient spikes are worse at 160m and 80m.
? ? ? ? ? ? A also operate the QMX remotely and am very careful to ensure I don't get ATU spikes.
?
DX on my QMX-PLUS !

 

QRP-Labs QMX-PLUS at five watts to a forty meters long end-fed wire in the New River Valley of Virginia. Tnx QSO, Al, F5MYH . 72.
Bill, N4QA/QRP
Clear SWR Protection "S" through the USB port?

 

I have QMX+ bundled with a mini PC and I connect via remote desktop to run WSJT-X, etc.
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I have been using this setup with my QMX successfully for a few months.? It works well with my ATU-10 and Ultimax100 antenna .
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The QMX+ however, has gone into SWR Protection a few times.? And with the rig in another room, I would like to be able to reset the "S" remotely.
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Through the terminal connection, perhaps?
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Is that possible?
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Any info/advice appreciated .
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Tanks,
Sam Hanie, AC4OW
Re: QDX - Windows 10 help!

 

hi
on windows pls also try turning off the bluetooth, some times it messes up the COM ports
73 DE muhsin TA1MHS
Re: QDX rev 6 image freq problem

 

On Sat, Oct 12, 2024 at 06:12 PM, Jerry Gaffke wrote:
And be aware those binocular microscopes can tip over when swung to the side.
Not with this stand, the reach of which lets me cover most of my assembly bench. ?
73, Don N2VGU
Re: QDX - Windows 10 help!

 

Thanks Alan. I shall try that.
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73s
Roger G3XBM
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Re: QDX - Windows 10 help!

 

On 13/10/2024 09:24, Roger Lapthorn via groups.io wrote:
There is a known issue with Windows (not Linux) with the QDX not being recognised..
Roger,

The known issue is that the QDX has to be power-cycled.
When I reboot W10 I cycle the power of my permanently connected QDXs, then they are recognised.
If you remove the USB plug then a QDX power cycle is required to use it again.

73 Alan G4ZFQ
QMX+ Dev Kit

 

In the assembly_2_00.pdf manual I can read in the Para 4.Dev Kit option "if you wish to
make connections between the main PCB and Dev PCB (pin headers are available from the QRP
Labs shop spare parts section)."
I searched the shop.qrp-labs.com page "spare parts" and did not find these pin headers. Where can they be found?
73 - Pierre - FK8IH
QDX - Windows 10 help!

 

I have not used my QDX for some time and I have forgotten the sequence in which things have to be connected. Please can someone remind me? It worked in the past so I know the QDX is fine.

There is a known issue with Windows (not Linux) with the QDX not being recognised..

After struggling?for ages, I have given up.

I am sure this has been on before, but there are so many posts.

Cheers
Roger G3XBM

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