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On Sat, Mar 29, 2025 at 01:17 PM, Brien - KE7WB wrote:

Plug in the USB cable from computer to QMX and then try to turn on QMX.? This yet to be fully understood scenario worked for me on a couple of occasions.

Brian, if this works when you can't switch on your QMX without the USB cable something is wrong with your setting / your QMX!!!

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73 Ludwig

Jindra,

Right now for the beta,

a) You need to use an external mic.? The internal mic is not currently supported.? While the internal mic does have some functionality, it won't work well for QSOs - it is currently being use for noise cancellation for the external mic.

b) An external PTT is currently required with an external mic.

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I'm not sure the internal mic will be supported in the first non-beta release.? Since there is an easy alternative (external mic), it may be a lower priority to fully support.? But when it is supported, Hans will let us know how to control PTT.? We may need to still plug a PTT button in the paddle jack to use it, and use VOX if we don't want the external PTT button.? He may also decide to change one of the current buttons to work for PTT, but I don't see a good combination without sacrificing something useful for SSB.

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Stan KC7XE

On Sat, Mar 29, 2025 at 06:12 PM, @Ludwig_DH8WN wrote:

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When the controller starts to use SMPS, the LCD goes all blocks so I guess the 5V rail is damaged.

Strange. In some failure situation going to Diagnostics may reduce input current. Do you know your supply voltage every time?

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Sorry, failure. It should be:

but if I try to access the hardware diagnosis function, QMX+ crashes and the USB connection is lost.

Strange. In some failure situation going to Diagnostics may reduce input current. Do you know your supply voltage every time?

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73 Ludwig

On Sat, Mar 29, 2025 at 04:19 PM, Zhenxing Han N6HAN wrote:

The steady power consumption after SMPS bootstrap is about 22W so something is probably shorted.

This would mean 1.8 A @12 V! To much and dangerous for the QMX.

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What do you mean by "normal"? Before SMPS is working the display should be blank and dark.

How do you know the controller is working and starts the SMPS in this state?

Strange. In some failure situation going to Diagnostics may reduce input current. Do you know your supply voltage every time?

When seeing a damage something very bad was happening.

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Could you tell a bit more about? Is it important it was USB-C? How did you feed your QMX by the USB-C PD power supply and how did you feed it later?

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73 Ludwig

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On Sat, Mar 29, 2025 at 08:19 AM, Zhenxing Han N6HAN wrote:

Long story short, I managed to damage my fresh built QMX+ by trusting a USB-C PD power supply too much...

If you use an external trigger module with a PD power bank, it is easy to accidentally let it switch to the 20V mode and break your QMX.? I know this from my sad experience.? But now I only use a fixed PD trigger cable, and it always works fine.

The symptoms are that I'm still able to power it up and the display is normal before SMPS kicks in. When the controller starts to use SMPS, the LCD goes all blocks so I guess the 5V rail is damaged.

I'm not sure your analysis is correct.? How are you determining when the SMPS kicks in?? The 5V supply is only an SMPS supply, and it is what powers the display LCD and backlight.? So if the LCD ever comes on, it is because the 5V SMPS is already going.? But it could still be damaged in some way

Visual inspection shows 74ACT08 is damaged as well.

So this could be from an over-voltage on your 5V rail.? Did the fault happen while transmitting, or receiving?? If transmitting, something that blows your finals could also blow this device.

The terminal application is still working (so 3.3V is fine?), but if I try to access the hardware diagnosis function, QMX+ crashes and the USB connection is lost.

Hmmm... this should hold a clue.? Ludwig, have you seen this?

The steady power consumption after SMPS bootstrap is about 22W so something is probably shorted.

Yes, that is way too high for any mode of QMX+ operation.? So something definitely is shorted.? Your receive mode power consumption should be about 1W.? Do you have a way to limit the current into QMX?? For further debugging, until you find the fault and get a successful power-on at normal current draw, you should limit the current to 250mA to avoid damaging additional circuits.? Also it is best to reduce the voltage to about 7V.? Since things are kinda-sorta working a bit, your 3V and 5V protection diodes seem to have saved you from extensive damage, and are not likely damaged themselves.

I have an unbuilt QMX+ board that I can take components from. Really appreciate anyone could help me narrow down the components to check/repair. I was trying to use QMX+ SSB to work some WPX SSB contest stations... Really wish I could still make it... ?Many thanks!

It is really hard to say what all is damaged.? It looks like you didn't hit it with 20V like I did to mine,? since yours isn't totally broken.? I blew Q108, D109, IC403 and the TVS input protection diode, D110.? But it seems your D108, D109 and D100 are probably fine, since all voltages still power on.? Maybe you are lucky and only IC503 is blown - and it could be shorting the 5V supply down after the receiver/transmitter are configured.?

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So my best shot-in-the-dark guess at an action plan is to remove IC503, and see if the short is gone, preferably by measuring the resistance between Vcc and gnd, which should be a few k-ohms.? Then powering up with a current-limited supply to see if it comes up, and things start working again in receive mode.? Then replace IC503 with a new one, and power-up with a current-limited supply, check the diagnostics, except LPF sweep and SWR sweep (which will return poor results until you increase the current limit).? Then if all looks good, increase the current limit and try an SWR sweep, LPF sweep and diagnostic mode Tx. ? You may find that your finals are also smoked and need replaced.

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Good luck.

Stan KC7XE

Hello, I tested the internal microphone in the menu microphone test. Nice. Now a question: once the beta firmware results in a release, what will be the way to transmit? All controls seem to have already a function and there seems to be nothing left for the PTT function.

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Jindra

Have in mind the change to daytime saving time this weekend.? ( at least in DL)

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Martin

DK3UW

On printing, I usually print 2 pages to a sheet and double sided and use 'draft' print quality. That makes the cost of paper and ink much lower - maybe about 1/5th the cost of full size, normal quality.?

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73, Dan? NM3A

Building from a screen works well, but I prefer to check off things as I go. However, the biggest reason to print things out for me, is to document any issues or changes that I make to that particular unit. I have built many QRP Labs kits and they are frequently different revisions. If I don't document each one , it is a nightmare figuring out what I did on each one when a later mod is needed or wanted.?

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73, Dan? NM3A

Paul, it sounds like you may have general audio and/or receiver problems in your QMX hardware.? Even with a simple end fed half wave antenna, unless it is laying on the ground, you should be able to hear lots of cw signals, from far away, at least at appropriate times of day for the band you are tuned to.

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Try this - put your rig in digi mode, and tune to 14.074, anytime mid-morning to about 9pm or so local time.? You should clearly hear the tons of FT8 operators with their slowly modulating tones.? You may need to turn the volume control a couple of revolutions to get the level up.? If you have any trouble getting a strong audio signal of the FT8, we need to debug something in your receiver/audio chain or overall setup.

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Stan KC7XE?

Delivering SSB for the QMX/+ is the big announcement for this year! ? ?

Order a QMX+, it is a great little radio.?

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Steve KA0SM

Long story short, I managed to damage my fresh built QMX+ by trusting a USB-C PD power supply too much... The symptoms are that I'm still able to power it up and the display is normal before SMPS kicks in. When the controller starts to use SMPS, the LCD goes all blocks so I guess the 5V rail is damaged. Visual inspection shows 74ACT08 is damaged as well. The terminal application is still working (so 3.3V is fine?), but if I try to access the hardware diagnosis function, QMX+ crashes and the USB connection is lost. The steady power consumption after SMPS bootstrap is about 22W so something is probably shorted.

?

I have an unbuilt QMX+ board that I can take components from. Really appreciate anyone could help me narrow down the components to check/repair. I was trying to use QMX+ SSB to work some WPX SSB contest stations... Really wish I could still make it... ?Many thanks!

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73 de N6HAN Zhenxing Han

Thanks for confirming what I thought. Looking through the manual, and as others have stated, I think I can probably get away with using a tablet I have here, or, as it's probably not going to be a 'couple of evenings' build maybe clear some space in front of the main PC monitor and use that area for the build instead.

Hi Hans,

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I spent a couple hours adjusting the 20m band edges and center frequencies. I even tried the example given by Ellis (/g/QRPLabs/message/141909) and used that as a reference point. It always goes just beyond the 500 mark on the x axis and no more.

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Mel. M0KMD

A puzzle resolved?

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I tried various bands and modes, but I failed to enable my QMX+ Tune SWR function for more than 1 second,

far less than this old duffer could work an "antenna tuner" in his best days.

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Hans, in a You Tube video, shows how that function works in the QMX, continuously keying tx and showing the resulting SWR,

for up to 1 minute; sufficient time for this Ol Geezer to "tune er up".

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Being slow in the head, and getting no better, after a couple of days I "discovered" that with my QMX+ connected to a PC, connected to? WSJT, the Tune SWR only keys up

my QMX+ for 1 second and does not time out after 1 minute. When WSJT-X is closed, the function works as advertised... Now, happy old dog.

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Da Ol' Dog/wa4hei

Hans aren't you on vacation!?

Enjoy

Chris

Plug in the USB cable from computer to QMX and then try to turn on QMX.? This yet to be fully understood scenario worked for me on a couple of occasions.

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Brien - KE7WB