开云体育

Greetings! First post. I'm a seasoned electronics kit assembler with above average skills. That said, I have virtually NO skills with radios, but am a quick learner... I'm confident the electronics assembly is OK, but unsure about the coils and possibly enamel coating issues.?

This is a screen cap of the results from ADC I/Q test:


Based on the 1_00_027 operation guide, this should be a pair of sine waves slightly timed differently. All of the bands are pretty similar, and most tests are way off like this.?

I suspect the trifilar phase splitting is shorted and needs rebuilt, but wanted to make sure before I redo it. My concern is that when I twisted the 2 wires together, I used a drill and may have wrapped them so tightly the wire cut through the enamel coating.?

In the Operation guide, it seems to indicate this trifilar phase splitting transformer tends to be involved when multiple tests are not normal.?

What do you think?

And THANK YOU in advance!

I can’t claim to be an expert yet (just finished my own build today!) but have a few questions to help out where I can:

?

I would be surprised if just tight winding caused a short… but a bad solder joint or not-quite-melted enamel could certainly cause problems.

?

My main suggestion would be to not use IQ debug too soon in the testing. I think it depends on lots of things working right before it will even give valid results. For example, if there is no TX power, it won’t be sending much signal in during the test (your values seem much smaller than what I get on mine)

If you think that one part is wrong then look for tests that don't involve it.? For example the hardware diagnostics Tx test doesn't use the trifilar transformer because it is only in the Rx path.? Set a low voltage and low current limit (7V, 500mA) and try Tx.? You should see Tx power and? a low SWR.? And check the peak voltage across your dummy load, this should show roughly the same power as the QMX+ reports.

?

If there is no Tx power on any band check L502 and T501 for bad soldering.

If Tx power is indicated by the peak voltage across your dummy load but not shown in the QMX diagnostics check the soldering of T507.

If some bands give power but not others check the soldering for the toroids in the LPF used by the bands that don't work.

?

As for the trifilar toroid the only time it's practical to test for shorts is when it's not installed.? Your best option is to unsolder it and check that there are no shorts.

?

It's probably simpler to start with getting the Tx to work because the signal levels are higher so more easily detected.? Once Tx is working the simplest Rx test is to connect an antenna and listen.? You should be able to hear FT8 on 20m almost any time, maybe use your PC to decode it.

?

HTH

Chris

?

?

Yes, I meant 3 wires on the trifilar toroid. I twisted it 60 turns, while connected to a drill, with moderate tension to keep it straight. When measuring for shorts in-circuit, all the 6 wires appear to be shorted, but this is probably at least partially because it's still in-circuit...? I'll be taking it out today and checking for resistances again, just to make sure.?

You’ll need to fully remove the trifilar one to test it. Ensure the correct matching pairs are definitely in the right holes

--

Daniel ZL2DTL/ZL4YOTA?

?

?

Also, more importantly. Does it put out any power into an antenna or dummy load??

--

Daniel ZL2DTL/ZL4YOTA?

?

?

I think I found the issue. The trifilar toroid was fine, no shorts. That said, I started checking the other toroids for continuity - in-circuit. Now each of these was soldered at 800 degrees F for 10 seconds. Despite that, many of them do not have continuity, meaning the enamel coating was still present. My solution is to reheat each connection and rub the wire with the solder tip. This abrades the coating off. So far it works, but in the future, I will be hand sanding the ends of all wrapped enameled wire in the future...?

RE: Daniel ZL2DTL? ? "Also, more importantly. Does it put out any power into an antenna or dummy load?" ?I don't actually have an antenna yet. IU assembled the dummy load and have been using it for the tests, but still waiting on parts and wire for an actual antenna. The remaining parts to build an EFHW antenna should be here tomorrow, and I'll be able to test with an actual antenna then...?

I reheated every toroid/transformer connection that involved enameled wire and after aggressively rubbing the hot tip on the wire, all connections work through all the toroid coils! around 80% apparently still had enamel, even after being heated at 800 degrees F for 10 seconds! They now work and all of the tests look better, but there's still issues.?

RE: Andy Dawes N7LFO

"

1. What do the other tests look like (you mentioned multiple tests not being good, but how and which ones?)
2. Does it RX or TX as expected?
   1. For me, I had an issue with very low TX power that I traced to a bad solder joint on L502 and resoldering it resolved things
3. You said “two wires” but I assume you mean three… for the trifilar winding.

Yes, you can run T (TX) from diagnostics screen. SWR doesn't mean anything if there's no output power. I had a bad joint at the L502 (which all output goes through) and after fixing that, saw 3-5W on all bands into a dummy load. Good luck, sounds like you are on the right track!?

I've never had much luck with the "enamel will burn off when soldering" approach. Sometimes it works but just as often it doesn't. I always scrape with a razor blade and give it a few swipes with a folded scrap of sandpaper before wiping the wires clean and soldering. A little touch from a flux pen is not a bad idea either. It's satisfying to get it right and watch the molten solder wick into the PCB hole and adhere tightly to the copper wire.

?

On Mon, May 5, 2025 at 01:33 PM, Ahand59 wrote:

I agree 100% on your wire prep. With all the coil wire joints in the QMX and QMX+ this is critical for a successful build.

I strongly agree with your comment about use of a flux pen. For years I have a plastic syringe full of rosin core flux that I use on any larger than average solder joint. Another thing about flux is that if you don't like the solder "points" that are often left behind, coat the solder with flux and melt it. It'll go back to a round blob like we expect... Additional flux may make cleanup a PITA, but it really makes the soldering easier and look better...?