开云体育

Hi all,

Firstly, thanks Hans for a well designed kit, I've been waiting for a large qmx that I can actually build. I built this over the weekend, probably about 10-12 hours all in at a relaxed pace.

Most frustrating bits of the build were the 160m toroids. Kept losing count and then counting the turns was a challenge in and of itself. The 38 turn one must be at about the limit of turns possible? About 20cm of each enameled wire left over and 2324 capacitor cutoffs. The RWTS thingy wasn't necessarily difficult, but it was hard to feel confident in it. I think a few more pictures of it from a few angles would have inspired more confidence.

Only other point of note, my laptop track pad became very unresponsive when I plugged it into the QMX+ for the firmware install. It was connected USB c to USB c and it's an HP Envy X360.

Very very happy it turned on without issues.

Just wondering if I should be concerned about these power levels, specifically 40m and 30m. I.e. concerned enough to refrain from using the 40m band (or even tx in general) without fixing it.

160m 5.5w
80m 4.7w
60m 3.8w
40m 1.4w
30m 0.25w
20m 2.9w
17m 2.9w
15m 4.0w
12m 2.8w
11m 3.6w
10m 2.4w
6m 0w (my power meter isn't rated below 30MHz so hopefully that's why this is 0...)

What areas would I need to look at to check soldering, I assume the bands specific toroids, anything else?

Also are there any tips around the toroid spacings to increase power output? I know there was a tips and tricks for the QCX+ I built which got it from 4W to just a bit over 5W. I run a compromised antenna so every watt counts.

On Sun, Jul 14, 2024 at 01:41 PM, M0WAS wrote:

Hi all,

Firstly, thanks Hans for a well designed kit, I've been waiting for a large qmx that I can actually build. I built this over the weekend, probably about 10-12 hours all in at a relaxed pace.

Most frustrating bits of the build were the 160m toroids. Kept losing count and then counting the turns was a challenge in and of itself. The 38 turn one must be at about the limit of turns possible? About 20cm of each enameled wire left over and 2324 capacitor cutoffs. The RWTS thingy wasn't necessarily difficult, but it was hard to feel confident in it. I think a few more pictures of it from a few angles would have inspired more confidence.

Only other point of note, my laptop track pad became very unresponsive when I plugged it into the QMX+ for the firmware install. It was connected USB c to USB c and it's an HP Envy X360.

Very very happy it turned on without issues.

Just wondering if I should be concerned about these power levels, specifically 40m and 30m. I.e. concerned enough to refrain from using the 40m band (or even tx in general) without fixing it.

160m 5.5w
80m 4.7w
60m 3.8w
40m 1.4w
30m 0.25w
20m 2.9w
17m 2.9w
15m 4.0w
12m 2.8w
11m 3.6w
10m 2.4w
6m 0w (my power meter isn't rated below 30MHz so hopefully that's why this is 0...)

What areas would I need to look at to check soldering, I assume the bands specific toroids, anything else?

Also are there any tips around the toroid spacings to increase power output? I know there was a tips and tricks for the QCX+ I built which got it from 4W to just a bit over 5W. I run a compromised antenna so every watt counts.

Generally looks good. I would check the 40/30 m toroids for proper windings number. Ifthey are correct then play with turn spacing.

6m is more concerning- it should show something even if the meter is not designed for or accurate at 6m. There I would suspect a bad solder joint.
?
--
73, Dan? NM3A

Okay, resoldered the 6m toroids, got them nice and toasty, the solder flowed nicely. I'm now getting 2.6W output which is broadly in line with everything else. Must have been a bad joint before but they looked okay. 30m and 40m still a concern. I checked the number of toroid turns and they're exactly as the manual says, I shall give the toroids another resolder. They look okay too, but obviously that doesn't necessarily mean anything.

The burning off of the enamel was the bit of the build which I was always least happy with, very little positive feedback that it's been done correctly. I checked continuity after every toroid but who knows.

Anyway, finally got it hooked up to an antenna and got the following results:

CW CQ on RBN


FT8 CQ and QSO on PSKReporter


And little does he know it, but PD5DLB was my first FT8 contact on my QMX+, I was received at +5, and I gave him a +3 report, 500km away.

Interestingly when keying down on CW on 20m I get 2.7W, but when transmitting on FT8 the meter showed 3.2W.

Still working on my CW copy speed so a CW QSO will have to wait a few more weeks/months(/ever?) till I've built up enough confidence.

Both the maps above look quite normal to me, I will have a bit more time towards the end of the week to do a proper test and compare with my QCX+, and QDX (pre-assembled). I also have a Z-Match ATU in transit so I can shift from my attic 20m dipole to my attic G5RV-JR (jury is out on how well that is going to work...) to hopefully get on some different bands (although 40m not looking so promising at the moment).

On Mon, Jul 15, 2024 at 05:23 AM, M0WAS wrote:

The burning off of the enamel was the bit of the build which I was always least happy with

Get yourself one of these Knipex 15 11 120 strippers, happiness awaits.

Does anyone else remember Stripex/Strip-X? It was a foul-smalling brownish concoction of phenol etc. which was used to chemically strip enamel.
Dip it in, wait a second and wipe off the enamel cleanly. I am sure they pulled from the shelves for a reason but it worked great.
73, Don N2VGU

Up to 1.6W on 40m and 0.75W on 30m now. Resoldered and jiggled about the windings. I think next step is taking them out completely and just really tightening up the turns. The fact that doing that and nothing else has increased the power output on 30m from 0.25W to 0.75W means it's all to do with them I think.

Up to 1.6W on 40m and 0.75W on 30m now. Resoldered and jiggled about the windings. I think next step is taking them out completely and just really tightening up the turns. The fact that doing that and nothing else has increased the power output on 30m from 0.25W to 0.75W means it's all to do with them I think.