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Hello Hans

I have translate into french the QLG2 Manual.

Many thanks for this new kit.

73 QRO
Gilles F1BFU

I completed assembling my QMX+ kit last week.? What a neat kit and apart from having to use strong glasses and a magnifier it was successfully put together.? Hans should be very proud of his quality products.?
So far testing has shown that I have some shortcomings with both the TX and RX which I hope someone may help with.?
After assembly, checking & rechecking soldering and parts placement I switched on and loaded the firmware, everthing appeared ok.? Voltages and current flow all good.? Noise in the headphones and power into the dummy load. After initial testing at 8V the voltage was increased to 11.5V with no ill effects.
I documented my findings below:
All filter sweeps (RF filter, LP filter) appear acceptable and similar to those published. (Using PUtty).
Receiver
The MDS ( minimum discernible signal) is 5uV which is not great and this is consistent across all bands 160m - 6m.? It is quite deaf.? Tested with my HP8656A Signal Generator.
There is a huge difference in audio output at the same volume setting between the CW and Digital modes taking about 3 complete turns of the audio gain to get around the same level of noise in the headphones.
On some bands there is a continuous low level audio tone of 700 to 800Hz which can mask the beat signal from the Signal Generator.
On switch on the unit defaults to 1.8382 MHz, which is fine but on turning the tuning knob in either direction the frequency jumps to 3.2000 MHz.? On pressing the band change switch it then performs normally and goes to the 80m frequency and so on.?
I have resoldered all the toroid leads and measured continuity to their pads.

Transmitter
Power output was measured with an oscilloscope across the dummy load and with PUtty.? They didn't differ much.
Band????????? Power????? Total current (@ 11.5V)
160m????????? 5.8W??????? .93A
80m??????????? 4.6W??????? .63A
60m??????????? 3.3W??????? .47A
40m???????????? .75W?????? .25A
30m???????????? .36W?????? .23A
20m???????????? .2W???????? .22A
17m??????????? <.1W??????? .19A
15m???????????? .1W????????? .16A
12m???????????? <.1W?????? .15A
11m??????????? <.1W??????? .14A
10m??????????????? 0?????????? .12A

I was unsure if I had wound T507 correctly so rewound it but it made no difference to the measurements.
The two main items that puzzle me are - 1. the decreasing output from the tx with increasing frequency and 2. the constant level of deafness of the receiver.? It appears it must be something common to all bands.
But if anyone can give me some tips on all the above items about how to proceed, I would appreciate it.
Regards
Greg, ZL4GW

Hi Ahmed
I have run the same tests in the last 2 days on my QMX+.? I found I had some weird pictures too.? Firstly I reloaded the firmware after reading an earlier blog.? This fixed the filter tests.? However the SWR test is still wrong and I believe it is because on the higher bands my QMX has a very low output power (one of my problems) and the SWR can't be properly measured.? There are quite a few examples of filter plots on this site to give you an idea of what others are finding.? I hope this helps.
Regards
Greg

My QMX had been working great. When listening on 40m during some qrn, but not actually thunderstorm at my qth, QMX shut down. Rebooted and rx on 80, 60 and 40 m has gone. -50db or so on audio sweeps. Very strong sigs still just audible
30m and 20m are not affected and signals coming through fine.
Reinstalled firmware, still no rx on the lower bands.
Transmit side working as before, full RF out on all bands.
What might have have failed??
The bandpass MUX?

Rich
G4PCE

Gwen,
Pretty neat stuff! I drooled over those kits. Unfortunately, we had even less money so all I got was a newsprint book of science experiments. I made do with one of those giant dry cells, wire and bulbs. I did make a working (sort of - only got the loudest local station) radio with pencil lead and a blue razor blade for a detector.?

The local TV repair man let me hang out in his shop, but I didn't learn very much.?
--
73, Dan? NM3A

I'm thinking of putting a small class D audio amp and tiny speaker/s in my build when I get that far (along with battery/charger and possibly ATU)
It looks as though I can pick the audio up from JP301 pins 3&4 which are labelled as switched so hopefully are the connections that get broken away when an audio jack is inserted into the earphone socket. Can anyone confirm that thats correct?

Thanks
Steve

I recently build my 6th kit from QRPLabs (2nd QMX, first QMX MB) and it is really a pleasure with those high quality kits and manuals.
There is one difference as I the first time experienced to much power on a band, even without teaking, at the last kits I had to fiddle/tweak and fight to get around 4,5Watts Pout.

Q: How huge is the risk on 20m, if the rig used in CW only and what would you suggest?

Details:
All toroids are wound according to the manual, everything worked as expected and the BPF and LPF sweeps are spot on.
The transformer has been wound in 12V RWTST style, PWR measurments are done by providing 12,0V using with lab power supply.
All Bands are around 5 Watts, only 20m is much higher and concerning me.
When I try to tweak the LPF to reduce the 20m Pout, 30m is affected as well and goes under 3W.

Power meassurements with an oszi at a QRPLabs dummy load showed following figures:


73 de
Alex, DK4FT

On Tue, Jun 18, 2024 at 12:03 AM, Barry VA7GEM wrote:

On Mon, Jun 17, 2024 at 01:54 PM, Danny Bower wrote:

On Sat, Jun 8, 2024 at 02:11 PM, Barry VA7GEM wrote:

Danny
Great amp. Have been using mine for 15yrs with FLEX1500, now replaced with QMX HB.
There is a mod to set the input power to 5W or 10W. With the QMX (9V) running at 8V
there is enough drive to realize full 50W out on bands 20 thru 10.?
GL de Barry

Many thanks Barry - so, do I set TX PTT to be Grounded? And how do I wire up the PTT plug for the QMX and DIN on the THP?

Have been having a play with the THP and my FT817 and it seems to be mighty good :)

Vy 73 de Danny M0SDB

Danny
QMX set PTT GND es wire tip(+) es sleeve(GND). Tip will ground when engaged.
On HL50B Wire QMX GND to ACC pin6 and wire QMX Tip to ACC pin 8.
Enjoy my friend
'Barry

FB indeed Barry es tnx fer your help. Really appreciated. And that's great news.

Just sometimes when I'm out and about I fancy a bit more poke. I was going to buy something like the Xiegu G90 but then this came up.?

It was a little pricey but I know how good THP stuff is and I figured it would be more versatile as I could use it with more radios.?

Will pair with the QMX+ just nicely I think :)?

Vy 73 de Danny M0SDB?

QMX 80-20, Rev 3, 12V

Got it to a point where swr and lpf sweeps look good for all bands.

Managed to do some test transmissions on 40 and 20m :-)

All my audio filter sweeps have a flat yellow line, but the red bit is only 10ish dB down, not 60 as shown in the operations manual.

Not getting anything? on rx other than static. Sounds the same on all the bands. I'm tuning to freq where can see strong signal on local sdr and also hear signals on my base radio.

Changed the audio setting to relative, and volume knob is increasing and decreasing sound ok.

Any suggestions on what to check next pls ?

Hi Matt N3AR,

You are correct that EN11-HSM1AF15 is just a close approximation of what is normally sourced from QRP Labs. However, I was able to make it work with some mechanical modifications. The center line of the shaft is offset from the original part towards the two-terminal end. The metallic body of the part will physically interfere with soldering these two contacts to the Control Board. I used a metal file to remove material at a 45 degree angle from the body edges. Once I had removed enough material to have enough clearance to solder the contacts to the Control Board, I used the file to round the sharp edges of the newly created 45 degree surface. I found that all of the leads were really too short and had to add length with some spare component leads I collect in a small envelope for just such purposes. Before soldering the part to the Control Board, I coated the body of the encoder with Kapton tape just to help to avoid shorts. It works, but its a pain.

I saw Hans G0UPL's response and found this on Amazon in the US. Looks the same except the shaft appears to be longer than the original part. That is easily remedied. I might order a handful of these and see if they are a better alternative.


73,
Doug - KG5OA

I had a look at the schematic and identified the toroids, capacitors, diodes and inductors related to 60/40m. Re-flowed 5he solder on all of those and the swr and lpf sweeps look normal now.

Still have weird audio filter and image sweeps, but will start a new topic on that.

if YOU were a YL you'd never being? those dates and ages.. .we can all add up ... .mostly.? :-))

Hi Geoff,

My QMX does the same thing.? The story with mine is that initially there was a short on between the fets on the plug in regulator board.? I fixed this short by heating up the fet and sliding it sideways.??
Unfortunately, while fixing the short I created a solder bridge on the regulator board between two very close tracks.??
I found the short after a quick power up but the damage was done.
The short damaged a port on the processor which controls the power off process.?
So while the QMX powers up by the pushbutton, it now won't power down.? I've decided to live with it the way it is now as replacing the processor would be a big job (if I could obtain one!).

Cheers,
Glenn VK3YY.

Hmm, well, that is working today... I'm confused because I'm 99.99999% sure I tried turning it off and back on again several times last night with no luck, but the first try today worked.? I also tried turning it on first and then connecting it today and sure enough, same error.? Turning it off and back on again immediately recognized the device correctly today.??

Super confused... but happy to be moving forward.? Thank you!

I brought my QMX back from the dead with 2 new buck supplies, and a firmware update. Things look good on the terminal session except for the control board buttons which don't do much except tune the 80m band, and sometimes says shut down. There is still trouble in "river city" and since this issue I have a new QMX that works just fine. I'd love to know what is wrong with this little fellow, so if any talented qrp'er out there, with a real lab bench, would like to take a shot at resurrecting it, it is theirs with the provision that I can follow the repair efforts vicariously. Say $20 for the parts including both old buck supplies (one works) plus priority shipping ????

cheers,

Barry

I did some quick searching and couldn't find anything like this in the messages. Before I get out the scope and schematic, I figured I would ask.

I just finished my first QMX+ build. All seems ok except that there is a screaming loud tone (guessing 1Khz ish)? from the headphones on all bands,
controllable with the volume. No antenna connected. RF and LPF sweeps look pretty good except for 12, 10, 6 meters RF. Knobs appear to work.
Display looks good. Draws 110ma in RX. I have not tried any TX yet. One thing at a time.

So, does this sound familiar to anyone??

Thanks,
Tony
AD0VC