开云体育

Thank's, 12v,power supply 13.8v, 1 ampere in tx, I read power with terminal prog of qmx and meter of display on qmx, John.?

Insufficient data.?
Voltage built for (9 or 12)?? Actual voltage used for measurements?? Current consumption?? How did you measure/calculate power?
73, Don N2VGU

I received them from QRP LAB. I had to bore out the housing hole with a needle file.
--
73, Oleh, UY2ZA

Bryan:? Use 10X probe setting whenever possible, most probes have lousy frequency response in the 1X position.? Compensate your probes to their 'scope channel prior to use.
73, Don N2VGU

Thanks Guiseppe,
I have been exploring
Its pretty informative.
I still have not learned what the bnc-cable with two alligator clips is for. Im guessing low voltage DC say 40v or less.
--
regards,
Bryan, N0LUF

I finally replaced my oscope which I foolishly sold years ago. but struggle to remember how to use it.

does anyone know agood online resource to study up on using one?? im not taking about how to use the buttons and features but rather it's practical common uses.? like when to user the 1x,10x, twin lead probes, tracing circuits, do's and don'ts,? e.t.c.?
--
regards,
Bryan, N0LUF

I don't think Hans will commit to the month or even quarter.

I am going on the basis that Q4 2024 is the earliest when such option might be available. Considering this, I am currently slowly building mid-band version. If you find my earlier post on the subject you will find detailed instructions by other group members on his build and parameters used.??

Personally, I would see SSB implemented first, but this is just my take on it.

---------------------------------
73 de Marek SP9TKW

Hi,
what you can always do is to add a 5W 3dB attenuator to the PA input to lower the worst VSWR to 2:1.
Or you can change the internal 3dB to a 6dB attenuator.
In both cases you will need a double power at the?PA?input to get the same PA output power as now.
In the first case you will also loose 3dB at the receive.
--
73 Bojan S53DZ

That said, after fixing my ground issue with the QDX - see my other newer message on this issue - I'm now operating FT8 from my Fire Tablet with FT8CN. Yay!?

Hi,

I am about to order a QMX Kit but I would love a Mid-Band (40-10 or 40-15m) version. I know that are some of you, who modified a QMX for mid-band usage but I will wait for an "official" mid-band version. Hans has a lot on his plate, but I have to figure out if I should wait for an "offical" mid-band kit.

Can anybody tell me, if an "official" mid-band version is on the horizon (so available within the next weeks or at least before summer)?

Best & 73

Hello Peter,
welcome and thanks for joining us. It was one of the busiest WARC Parties for long. I had 6 QCX/QMX and I think there were even more. Also tha band was quite open. I later worked VK2 on 30 m? And on 160 I heard HL2 with god signal and DU very weak. No, they did not hear me

What did I do wrong?

I built my 50W PA for 20M - This is my third QRPLabs kit, having successfully built two QMX first time 'round (high and low band versions) so I get the idea of how the manuals and instructions tend to be set up, and I think I got the PA completely right, except that the input SWR is a mess, hovering around 3.0 at 14 Mhz. This of course isn't going to work.? I don't want to smoke my QMX. I'm crazy about these little radios. They both work so brilliantly.?

(Note, I was manually keying the PA to test before the latest 1_00_016 firmware came out, thanks for that, PA key-up is working as expected with the new FW)

R5 is adjusted as per the manual, plus tried a few percentage points +/- either way - no improvement. My antenna is a meticulously trimmed-for-20 dipole with excellent performance. I've also tried a range of different voltages from 12-20, and there's no meaningful difference in the SWR sweep when I change that variable. Also, the nano-VNA more or less agrees with the SWR sweep that shows high SWR on 20M. And of course, I'm doing these sweeps with the power amp keyed.?

I'm not an expert in PA, or really analog anything design, so I'm at a loss here. Nothing really sticks out on the schematic at this point in my education.? I re-wound the trifilar T1 a second time just for fun with a brand new set of wires, but the outcome is identical. High input SWR.? What if I removed a turn from the T1 transformer? Would that shift this nice low SWR dip I see at 10 mhz? Or added MORE turns?
?
If I wanted to run at 30M, then of course it looks like I'd be in excellent shape here, but I need 20.? As I understand it, having a SWR of 2 into a PA isn't even unusual, but 3 is a whole other story.?

I would appreciate if the group could share their knowledge and help me better understand what's going on and suggest avenues I could pursue to correct this. And please be kind, remember I'm new to this and trying to get into the hobby.?

Thanks!
Andy KA1PLU

The power connector comes in different lengths.
The one available from QRP Labs is correct, but I also had some I bought from another supplier.
I made up a longer cable using one of these without realising.
It took me a few minutes of worrying that there was something wrong with my previously fully working QMX before I realised that the power connector was intermittent.
The short one is just too short.
Using the previous cable immediately restored correct operation.
Enlarging the hole in the case would allow it to go in further, but that is a solution to a self induced problem…
Ive bought some of the correct length plugs!

On 12/02/2024 20:13, Jim Bennett / K7TXA via groups.io wrote:

I was hoping to have the IQ stuff sent to the SDR software on receive and the QMX still function as a Tx device.

Jim,

IQ mode transforms the QMX into an experimental SDR receive front end so a 48KHz receive bandwidth may be shown and tuned using CAT.
Any mode may be received within the 48KHz bandwidth.

It is a completely separate function, not an addition.

73 Alan G4ZFQ

Hans-san;? thank you for the nice radio.?
I want to disable 5M-band on my QMX in accordance with the Japanese regulation, however, it is still activated even though I enabled Japanese Limit on the menu.
I can't operate QMX before disabling 5M band on which we are not allowed to operate.
If anyone can help me with fixing this issue, appreciate it!

the coax was 3m long, made of RG174 cable. So, may be this is the culprit. I had another 4m long hyper flex cable, but I did not tried it unfortunately. Yes, I can try to add a counterpoise, and see if this disappears. Hope it will, because QMX was again a joy to operate.

It does not seem ridiculously short to me but I would still try to play with lengths and counterpoises.

Yannig F4IUJ