Thanks John,

I just checked the voltage across the dummy load with my scope: only around 200mV peak-to-peak (but at the correct frequency) on all bands (with some variation between bands).

I will check toroid T507 as I am not super confident in its' joints. It is also inbetween the RF jack and rest of the circuit, so could conceivably be the culprit.

On Sun, Jul 30, 2023 at 02:44 PM, Bill, N4QA wrote:

Hopefully this is now correct and there won't be any more ! Sorry !
72,
Bill, N4QA

Actually I don't mind it.

I've seen your posts over the last year or two, and it's a good reminder
of how little power can be used, and ow you've put to to good use a busted
rig. (I think that's right ?).

Keep on having your fun, and the occasional post helps educate the QRP brigade.
?
--
- 73 de Andy -

Steve

--
Jginaz

Hi all. I received my QMX several days ago and started building it today (Yay!).? I have a question on the separating all the small boards. Per the assembly manual (assembly_1_00f.pdf, I broke off the cutaway tabs as described on page 7 and removed all the small boards np problem.. Page 8 shows the separated boards? However, on my PCB, there is a long and wide piece attached to the LCD board and the mail board. (See attached.)? This doesn't look like it would break off too easily.? Any suggestions on how to remove it?? It's not mentioned in the assembly manual and I want to be extremely careful not to damage anything. It doesn't look like it would break way too easily.

-Thanks, Steve K1RF

Tnx QRPpp QSO, K5DDT.
72,
Bill, N4QA

I think I found the culprit! There were bad solder joints on a number of toroids that I had not noticed.

The RF sweeps look much better now, but they look very different from those you linked (mine often have two peaks?). Do these look "good" or should I investigate?

Paul,
Think it's correct now.
Apologies.
72,
Bill, N4QA

开云体育

Willie,
My TD is acting up. Please forgive me.
Bill

Perhaps I didn't explain what I was reporting clearly enough...

I am aware of the "P" issue reported earlier in this thread, as I had read the entire thread.

I'm reporting that I'm not seeing the "P" in digital mode, even though in digital mode, if "Practice" mode is in effect, the transmitter also appears to be disabled. I can recheck this if needed, but I believe that's what I am seeing.

This is confusing right now and results in the QMX appearing to be broken in digital mode. I believe that this will eventually need to be resolved one way or the other - either show the P in digital mode as well, or make digital mode ignore it.

Obviously, this is not a high priority problem as there is a workaround, but I thought the information would be useful for Hans to have while he's working on that portion of the code...

thanks again,

M

Hopefully this is now correct and there won't be any more ! Sorry !
72,
Bill, N4QA

开云体育

No, you're not. ?Plonk.

That was supposed to read.../QRPpppp !
72,
Bill, N4QA

Had forgotten my QDX output on 80m. Sorry for new Topic!
Tnx QSO, K8BCL !
72,
Bill, N4QA

The sweeps in this post look pretty representative:
/g/QRPLabs/message/105619

JZ

On Sun, Jul 30, 2023 at 8:50?AM clansd via groups.io
<clansd@...> wrote:

Thank you both, I will go through and perform those checks.

Is there anywhere I can go to see what these sweeps should look like for the QMX? It would be nice to have at least from a knowledge perspective as at the moment I am going solely based off of a photo in the QDX manual.

Thank you both, I will go through and perform those checks.

Is there anywhere I can go to see what these sweeps should look like for the QMX? It would be nice to have at least from a knowledge perspective as at the moment I am going solely based off of a photo in the QDX manual.

Chris,

I would look at the LPF for 30/20 meters (The filter is shared between these bands).? I would suspect that one of the toroids has an open connection.? Maybe try reflowing the connections.? The sweep signal must pass through the LPF to reach the receiver circuits.

The others have enough gain to work, so messing with them is unnecessary.

73
Evan
AC9TU

Hi all,

I just finished re-running the tests, with a different set of connectors. I have tested the dummy load and know it, and its' connectors are good. Unfortunately, the results are essentially identical to the ones posted above :(

I believe the issue lies with the issue seen in the RF sweep. Assuming that the signal strenth values are comparable between bands (eg. a value of -40 in the 30m sweep corresponds to the same power of sensed signal in the 80m sweep for example), we see the following:

Only in the 60m and 40m band RF sweeps are the signals strong in what should be their passpands, relative to the values shown in graphs for other bands. This lines up with our findings in the audio sweeps, which look roughly correct for both 60m and 40m, but are significantly attenuated for all other bands. Assuming that the generated signal first passes through the respective band's bandpass filter before the detection is done in both the RF and audio sweeps, this makes sense.

As for what might be causing this? I am not sure. Perhaps this could be a result of bunching up of toroid windings during installation? It would help greatly to know if there are any further tests that could be performed to further locate the fault.