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Re: Severe QMX+ audio distortion

 

On Mon, Dec 23, 2024 at 03:37 AM, N4REE - Bob wrote:
It seems to me that "severe" and "awful" are extreme adjectives that deserve comparison.? "Awful" compared to what?? For example, Thomas Witherspoon often praises the audio quality of the Penntek TR-45 Lite. In comparison, I find my QMX (same audio circuits as QMX+) to sound better than my TR-45, and less tiring to operate.? To what field-portable QRP rig are you comparing the QMX+ ?? (Anans and Flexes are probably not fair comparisons.)
--
72 de N4REE, Bob Easton - QRP CW forever
I didn't realise the QMX+ would demodulate ssb, I thought with the great narrow filters it was optimised for cw.?
I must give it a try when I get back to my rig.
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Paul
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--
G0TXL (Paul)
Re: Qmx+ 3D printed case

 

Hi Dave, I am curious what type of RFI you experienced, I have not experienced any with my 3d printed top.

Re: New QMX build questions!

 

Nice work, Chris! Those NanoVNA traces are excellent, as is your 3D print case.?
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73, Dan? NM3A
Re: Power Source for 50 Watt Amp for QCX Series

 

On amazon I went with a linear power supply.
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It has adjustable current limit that trips if something goes wrong.
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I think you need a supply that can put out something approaching 5 amps @20vdc
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I have seen the readout show over 4.5 amps on transmit.
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KORAD KD3005D - Precision Variable Adjustable 30V, 5A DC Linear Power Supply Digital Regulated Lab Grade…
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Re: QMX and power bank PD

 

Hi,
A few features/quirks that I have noticed with several different PD compatible power banks.
? ? ?All power banks will automatically turn off after a time out period if the load is below a certain level. This is to prevent the battery draining when the power bank it not in use.
? ? ?On one of the PD power banks, it does not instantly negotiate to the trigger setting for its USB-C PD port when using the ON/OFF button on the power bank.
? ? ?On a different PD power bank, if set to 12V, it tends to shut off and restart if there is a high in-rush current when the target load it turned on.

The QMX should not present a high in-rush current, so I would not expect any issues with the power bank being at the trigger voltage before turning on the QMX.

Whilst USB PD and QC provides a handy solution for powering the QMX and other devices, its primary use case is for a charging technology, and the points noted above are not generally a problem.

73, Dave
Re: QMX Oscillating SWR

 

Chris,
Thank you for this post.? My QMX had the "dancing" SWR issue. A Factory reset calmed it. Where the SWR was varying 1+, it is now varying? 0.01.
Re: QMX+ with Macbook Air (Sonoma OS)

 

Hi Joe,
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I use my MacBook Pro with Sonoma to connect to my QRPLabs Radios.
The radios just connect with a USB cable and there is no need for Macports or any other software.
See below for my macOS use of the Terminal program for making sure you can see / connect to the radio.
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The N1MM+ equivalent for macOS is SkookumLogger (). It connects to the QMX and gets the frequency and mode but doesn't control it. It's an amazing program that has templates for all the contests and can also connect to antenna rotors, keyers, etc.
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I also have other logging software: SKCC Logger and NAQCC Logger.
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My main logging software is MacLoggerDX. Also connects to the radio and antenna rotor (if I had one!).
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For RTTY I use flrig and fldigi. Logging goes to MacLoggerDX.
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For WSJT-X I use WSJT-X for macOS along with JT-Bridge and GridTracker. This all work together nicely with autologging to MacLoggerDX.
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These are my notes on using the Terminal program:
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Select from Shell menu:
New Window/Pro
To enable Control-S and Control-Q?
(you need Control-Q to exit menus):
stty -ixon -ixoff
To show connected ports:
ls /dev/cu.* OR
ls /dev/cu.usb*
To connect:
screen /dev/cu.usbmodem1101
Then press enter to get Diagnostics menu.
And away you go. Works great.
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Happy to help if you have any issues...
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Cheers!
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Pierre
VE3HQZ
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QMX Oscillating SWR

 

While working on another problem I had a strange issue with bad QRM coming through the radio.? I tried a number of things, swapping around coax, adjusting location of things, but couldn't supress it.? Then I noticed that my SWR was oscillating between 1 & 2....; running an SWR sweep confirmed the strange behaviour.? A power off/on didn't sort it, and switching band didn't seem to make much difference.
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Eventually, on a whim, I did a factory reset..... and it was gone!? Has anyone seen this behavior?? A software gremlin?? Or a hardware issue with my build?

Later, I noticed that doing an audio filter sweep leaves the radio making a lot more noise, which a power-off will sort.
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I'm hoping these are just firmware/bugs!? In operation the radio seems to be operating perfectly....
Re: New QMX build questions!

 

Hi folks, I've enclosed a few photos of my fix for the SWR/EFHW problem.
The images show the choke I wired up (with -30dB suppression on the NanoVNA), and a little box I made to hold it all together.? When attached to the EFHW after a couple meters of coax, to form a counterpoise, it seems to work great, and I can successfully run all the tests.?
This was my first time using Fusion 360 to design a box; part of the reason I bought the 3D printer.
Anyway folks, that sorted one problem out!!? Thanks for the help...
Re: New QMX build questions!

 

Re: mission impossible? QRP labs QMX power supply boards

 

Hans,
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Thanks for the response.
These PCM1804 failures are puzzling.
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Jerry, KE7ER
Re: RF output power on 160 and 80 meters

 

It's normal to get slightly higher output power on the lower bands, for the same input voltage.?
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72/73 de Enzo M0KTZ
Re: QMX and power bank PD

 

Thank you Dan, your input is much appreciated.
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73 es dx.
Re: Severe QMX+ audio distortion

 

The Agency (TV Series 2024–)

On Mon, 23 Dec 2024, 15:38 Ted 2E0THH via , <qrp=[email protected]> wrote:
On Sun, Dec 22, 2024 at 04:35 PM, Chuck @ w8mqw wrote:
I've been annoyed by the audio quality of some earlier kits
Chuck, I would seek some common denominator in your rig. These kits sound great. Sounds to me like you have an inpendance mismatch in your external audio monitoring.?
Ted
2E0THH?
Re: QMX and power bank PD

 

You need a trigger board or cable. Just make sure to plug it in to your PD power bank first, so it will make the negotiation before plugging into the radio.
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73, Dan - W2DLC
Re: mission impossible? QRP labs QMX power supply boards

 

Hello Jerry
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Chris wrote:? "Are the PCM1804 failures down to momentay voltage spikes?"
Hans replied:? "There's nothing to indicate or suggest this."
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There are lots of PCM1804 failures though, would be nice to get to the bottom of that. My impression from following this forum is that PCM1804 failures are mostly on the QMX, not on the QDX which has linear regulators.? I could be wrong in that.? If true that at least indicates something, though is by no means definitive.

It's wrong. I also thought like you, however I was not informed by my team until recently, that QDX had been failing their pre-shipment testing. It seems that our testing of QDX and QMX+ Rev 2 picks up issues with PCM1804 but testing with QMX does not (needs improvement). So it appears that the PCM1804 problem is not caused by the SMPS on QMX, because it affects QDX also (which has linear supplies). This indicates PCM1804 is a separate unrelated issue.?

73 Hans G0UPL
QMX and power bank PD

 

Is the QMX itself in any way capable to negotiate the required voltage with the power bank PD?
In other words is a 12V trigger cable required or not?
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I feel more comfy with a trigger cable as it steers away from any negotiating.
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73 es dx
Re: Qmx+ 3D printed case

 

开云体育

Beautiful work on the 3D printed case BUT: ?I was doing some testing with my QMX+ outside of the case and with any transmission the RFI interference caused problems that disappeared when I put it back into the case. ?You might want to cover the inside of the case with copper foil if you find you have problems. ?The metal factory case is metal for a reason.

Be the REASON someone smiles today.

Dave K8WPE

On Dec 22, 2024, at 2:38?PM, Ivica - YU1QRP via groups.io <yu1qrp@...> wrote:

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Finished my QMX+ a while ago and finaly got time to designe and print the enclosure.
Case is designed with future expansions in mind presented with removable accesories platform to be used for battery atu etc.
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Small foldable legs, bigger vfo button and slightly larger af button for better ergonomics.
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Re: 50W Amp - no output #50w #problem

 

Hi Roland,
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I suggest starting with the YouTube video from NA5Y:
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Several tests can point you to the problem area, even if you do not have an oscilloscope.? An RF probe like this one can be used to verify RF presence:
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You can build one if you have the parts in our parts bin:
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A short between D1 and the R2/R3 junction would indicate a solder bridge problem around that area.? Verify that the parts are installed correctly and that there are no solder bridges in that board area.? Unfortunately, that means removing the board from the heatsink.? Be sure to do the short-circuit tests when reinstalling the board.
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73
Evan
AC9TU
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Re: Severe QMX+ audio distortion

 

It seems to me that "severe" and "awful" are extreme adjectives that deserve comparison.? "Awful" compared to what?? For example, Thomas Witherspoon often praises the audio quality of the Penntek TR-45 Lite. In comparison, I find my QMX (same audio circuits as QMX+) to sound better than my TR-45, and less tiring to operate.? To what field-portable QRP rig are you comparing the QMX+ ?? (Anans and Flexes are probably not fair comparisons.)
--
72 de N4REE, Bob Easton - QRP CW forever
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