Just when you thought this topic met a fateful end, I've attached images of an adhesive heat sink applied to the PA MOSFETs in my low band QMX.? Because the TN0110 MOSFET's have the flat side facing up, that arrangement lends itself nicely to a low-profile heat sink.? ?In addition to the self-adhesive compound, it's compressed against the MOSFETs by the quarter-twist plastic tab on the LCD display.? ?

I make no claim that it's any more effective than the existing steel washer configuration but decided to try it anyway.??

Paul, W9AC

? ??

Hey Rob - good thinking - it never occurred to me that the Arduino would not be ttyUSB0 as it always pops up on that, but I'll try that. And I am running the trials on my RPi obviously as if on the PC it would be like Com7 or whatever. Although I got different messages there (the famous "Yikes!"), lol.

Thanks again,

73, Rob KC4NYK

After I finished my QMX 10m-20m it worked fine on the bench before adding the housing.?(ie TX fine, RX fine)
After I reassembled into its housing the hardware tests were all fine except the FR filter scans dropped ~40 db.? The following troubleshoot steps may be useful for others:
(1) Normally? the R401, R402? divider should provide 2.5V bias that can be observed in many places including at all T401 leads.? With my failed case I measured close to zero.
(2) By lifting the T401 lead fed by IC402 if it is the cause of the failure then the 2.5v bias will return.

(3) A final proof is to directly couple from L401 to T401's lifted lead through a capacitor.? I chose the L401 end point and used a 56pF capacitor.? The QMX then received fine on 20m.

Replacement 74CBT3253 is due tomorrow.
(I don't know the failure cause, I had not done the Rev 2 mod - done now.? Could of been ESD)

Pictures:

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IIRC, Hans has said that semi QSK is not yet implemented...

Roy- and group

Thanks for sharing that.?

Maybe this can be resolved if enough reports come in?

I noticed also that the SEMI-QSK function?setting (off or on) makes no difference, and keying appears to be stuck in full QSK.??

Jay

W6CJ

On Thu, Jan 11, 2024 at 9:33?AM Roy - KI0ER via <ki0er=[email protected]> wrote:

Hi Jay.

I'm having the same issue on my low-band Rev 1 1.00.014 QMX. Sounds just like yours (mine was home built).

I didn't notice it until the last firmware update as I recall.

If I turn the volume down low, I can almost eliminate that clicking noise at end of each dah or dih. I get that noise on all bands, but on 80M it's the loudest. I have my sidetone set to a static volume, so I can turn the volume knob down and send which eliminates that annoying (and loud) click distortion ... but would then have to turn it back up to copy incoming signals.

I'm surprised others are not reporting this issue!

73

Roy- KI0ER
Littleton, Colorado, USA

-- 
Paul -- AI7JR

?Roman,

the problem is "hi RX current".
The diagnostics3.pdf was made when transmitting. Why transmitting?

" I found that D108 is broken"
At the old or at the new board?
This means VCC (5 V) was higher than around 5.6 V!
Look at the circuit diagram at the end of the .

"The second 3.3V SMPS board on the VDD terminal should have 3.3V, I measured 3.05V."
Where?
Could you check voltages on both sides of D103 (see circui diagram) and voltage across D103?

73, Ludwig

The QSX was banned by the ITU, who objected to the use for some reason
of that specific Q code designator.

Hans is still fighting a legal battle over this, but his recent appointment to the
UN Security Council is slowly moving things forward.

- 73 de Andy -

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Also, be aware that lead time on assembled units is WAY out there! ;-)

Paul -- AI7JR

There is no QSX, Bill.? It is a planned radio, it is not an in-production radio.? The QMX is available assembled and tested.? Just choose the option from the drop down on the order page.

Joshua

-- 
Paul -- AI7JR

For IR thermometers /thermal cameras you can standardise the temperature readings (or the emissive to be exact) by putting patches of black matt pvc electrical tape on any shiny or otherwise difficult to read surfaces?

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Danny--?

I think he's saying there's no QMX device when he connects the USB. That's a different kind of problem.

Paul

If you can still access the QMX then just re-create the QMX folder. No need to scrap it.?

Plug the QMX into a 12v supply and turn it on, plug it into a USB port on your computer and you should see it as a storage device.

Open it up and you'll just see a blank folder. Right click in the blank folder and some menu options will come up - click New and name the folder QMX.

Then download, unzip and copy across the firmware as others have said.?

No videos are really needed, the steps are very clear in the manual if you read them.?

Note I made exactly the same mistake as you and wondered why I had an apparently dead QMX until I read those last few steps in the manual.?

-- 
Paul -- AI7JR

Nice of you to blame the operator for a faulty product, Thomas!

As has been said several times in this thread:

Battery:
The QMX was tested on several different power sources, including regulated 12V desktop power supplies, 12V car batteries, and LiFEPO4 batteries. The results were identical in all cases. The problems with the dials not working correctly is not due to the power supply or voltage thereof.

Antenna:
As no transmission was ever made on a non-resonant antenna, Thomas' statement, "The antenna used by N3JF is for sure a horrible mismatch and not advisable: bad receive and no protection on transmit" is disingenuous at best. The telescoping antenna worked perfectly for a quick receiver test with a brand new, just out of the box QMX -- checking for loud FT8 signals. Regardless of how "horrible" the mismatch was, for receiving, it fit the task perfectly. For transmitting, a resonant antenna is a? must, and in all transmitting tests, that's exactly what was used.

Buttons:
On a pre-assembled QMX, one that supposedly passed a quality control check, the obvious malfunctioning of the two major control dials should have been obvious and either fixed at the factory, or the unit should not have passed the quality control check It is clear that this QMX was only ever checked by hooking it up to a computer, not by using the physical controls on the radio. Neither of the two previous QMX radios suffered from this problem, and BOTH were tested in exactly the same way (on different power sources, as described above, adjustment of settings for double-click delay). Additionally, the height of the dials on their shafts were tested and adjusted, and none of it made any difference. The dials on this QMX simply do not work reliably 80%, or more, of the time for single-click, double-clicks, or long-clicks, regardless of settings, button heights on the shaft, or power source used.

Thomas' final statement, "QMX can certainly operated on digital with close to no button interaction" would be correct if, there were no other problems with this particular QMX, but, unfortunately, there are other problems with this particular QMX (as Hans has been made aware of in email). And that's what this thread is about. The QMX that I have in my possession -- not about the QMX in general, though receiving three defective QMX radios in a row, each with different defects, is pretty bad. Thomas' statement fails because this QMX radio could not be used on digital modes. This QMX radio should be able to be used on both digital and non-digital modes, like CW, like all other QMX radios should. But this QMX radio cannot because of the dial problems. I will agree with Thomas when he says, "If you are only digital the QDX might be the better choice."

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Brian--

So sorry to hear that! :-( My first QMX was partially working, then I must've done something (don't know what) to fry the MCU. My second was more successful, but I ended up sending it to Jeff Moore to resolve some arcane issues. (He does very good, and reasonably priced work, BTW!)

Why did you decide to put it into the scrap bin? The MCU is about the only part that isn't fixable (yet), and Hans was looking at how to make that available... I'm sure he has other priorities to deal with first! (Do you know it's the MCU?)

73, Paul -- AI7JR

Paul,

The qmx directory no longer exists. There was something that went wrong in the initial power up. I did not have a variable power supply or the equivalent available so I used a 12 v cell phone battery supply.

?The qmx is now in the scrap bin.

Thank you for taking your time to clarify the procedure. I wish there was a video that shows the power up of a newly completed qmx. I will keep your responses and use them as a guide if I build another qmx. They give an accurate outline of the power up process.

Thank You
Brian
KF4TJK

-- 
Paul -- AI7JR

Thanks everyone for all the help! With IC5 replaced and new TN0110 finals installed I now have balance at the IC5 ins/outs and balance in the finals heating. I measure ~5W out on 20m (consistent with the previous TN0110 and the original BS170 configurations). I only made one QSO so far, but I'm happy.

For completeness: if you replace IC5 with a soldering iron, your finals might want some protection (temporary heatsinking?). I was pretty careful, but I still killed at least one TN0110. My guess is that this was due to heat at the gate?

Returning to heatsinking... I again installed the finals standing up, with short leads, and I removed the middle heatsink for now. Running WSJT-X tune at full power the finals go from 70F to 100F in about 25 seconds (just holding my multimeter temp probe against the body). Interesting to me, the bare metal on the board intended as the BS170 heatsink seems to heat similarly. I'll collect more data as I try different heatsinks; interested to hear other people's results. I'll try with a thermal camera too, although the bare metal has low emissivity.

Starting a new thread on this one, as it appears that the slight damage to the corner of the PS board causes no problems. So, my high band QMX, Rev 2, built for 12v powers up just fine. Using Putty, all controls are fully functional. But, I get no RF output and the SWR protection kicks in immediately. Using a verified, short cable of RG-8x to a 50 ohm dummy load.?

?Using Putty I did an SWR sweep and on 20 meters it isn't looking very pretty:

?--

?Other bands show similar, nasty results.

Back in Putty, the "P" button in the transmitter diagnostic portion gives me 30.6 ma current draw. When I press "T", I get red for RF output and 0.0 watts. Voltage goes from resting at 0.6 v up to 9.8 volts.

Where would be some good starting points to check? I've made sure there are no shorts anywhere, and I didn't see any missed or cold solder connections.

Jim / K7TXA
Eagle, ID

SKCC 10447C
BUG 301

Jim, look closely at the connections on the SWR transformer.? I've found they are the most difficult to get a good looking (and working!)? connections at those points, especially the one which goes to the ground plane.? Besides needing a lot of heat they are close to other surface mount components.? But this area is consistent with what you are seeing.
Good Luck,
73? Bruce KG8IW

Hans & Igor - thanks for the replies! I got brave last night and applied power. No smoke, flames, or any obnoxious burning smell! Unfortunately, no RF output, either. Got a 50 ohm dummy load connected. I instantly get the SWR protection “S” on the display when I send a CW character. Ran putty and did the hardware tests - looks OK, but I need to revisit and pay more attention to the transmitter part of it. All seems to work except no RF. Hmmmmm…..
--
Jim / K7TXA
Eagle, ID

SKCC 10447C
BUG 301

On Thu, Jan 11, 2024 at 05:33 PM, Roy - KI0ER wrote:

I'm surprised others are not reporting this issue!

The issue is well known and very much reported :)