开云体育

It seems that some QMXs are OK and others not.? I get the impression that a QMX that is bad will consistently have problems and it would be nice to find out why.

?

My theory is that when a QMX starts to run at half power one bank of QMXs has failed and the other not.? Half the drive gives half the power.? It would help if someone could check this and ideally say which bank, the upper or lower.

?

A Component tester would be best, mine reports a goodish BS170 as a N-E-MOS Vt 2.57V, Cg 64pF, Rds 7.6 Ohm Diode V 711mV.

Measuring the resistance on each removed FET might give a clue, measure both ways - S to D and D to S.? I see infinity one way and 0.6 Mohm the other way.? If it's the same both ways it's failed.? (This isn't an infallible test, all it's doing is checking the parasitic diode.)

?

Chris

?

?

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

?

?

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)

Just finished my QMX+ build today, and after tracking down one bad solder joint on L502 I’m up and running with good TX power. I do see RF Filter scan that shows both 40m and 20m peaking off-screen to the right (high freq side). It’s like the whole curve shown in the manual is shifted about +3-4 MHz. The on-band level is about -10 for both 40m and 20m… but I don’t see any change when spreading or compressing coils on L403 (that should be the RX filter for 40/20 right?).

?

Not sure what to try next or if it even matters much. Other performance seems good and tests report results as expected.

?

Thanks!

Andy

I have brought the rig back to pre-calibration RF output levels. Not knowing what D-G-S terminals to test for what voltages, I replaced all four of the BS170 modules. Re-ran the PA-Mod test (it looked just like the example in the doc) and now my RF out is what it used to be.

?

SOMETHING in that calibration process is killing the finals, and I'm not the only one having the problem. I won't be doing that procedure again, until it is proven to have been fixed.

--

Jim / K7TXA
Eagle, ID

SKCC 10447T
BUG 301

I'll take one if still available.? Sounds like just the safe p.s needed.

73,

Ron K0OXB Liberty Hill, Tx

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!

Epilog:

?

The new finals arrived and I'm pleased to announce that my QMX+ is on the air!

?

I tried the "lay across the holes technique" for mounting the finals and decided it was too messy.

?

I want to thank everyone who provided helpful comments.? I never would have guessed that the pinouts were reversed on my Chinese bs170's.? I filed the remaining transistors appropriately.

?

Special thanks to Jerry, KE7ER, and Chris, G5CTH for leading me to the correct solution.

?

?

Well remember we can swing the power from there to 4 watts just by moving the windings. Try that first to see if more power is available. If a solder joint opened that’s another potential cause. I am hopeful it’s a small issue. Remember solder joints can look good and be open. Not sure the likelihood of damaging just one final. If bs170 were that easy to damage all my rigs would be broken.?

Hi Bruce

I have the same issue.? I have 2 X QMX+'s and they both perform the same on VOX.? Just as you describe.

Greg ZL4GW

Yeah, I am getting 1.6 into a dummy load.

?

Bob

Bob

?

time to pause. 1.3 watts is better than zero.?

a QRP dummy load is useful to have. Need to confirm issue is within the rig. If problem is real see if something lost its connection. I always suspect something I soldered.?

I don’t readily sense anything you said caused this. But best to be cautious. My favorite rig is in sickbay just now.?

curt

?

Looks like one of those fickle Windows mysteries, all back to normal now.

de VK6XT?

I waited for and yesterday installed the 1_02_000 firmware.? I did a bit of tinkering

with the EQ to get some more emphasis in the mid-range (and worth noting that

when I do live sound at folk dance events, I always cut back the bass and emphasize,

not too much, mids and highs to improve intelligibility of the dance leader, just as Hans suggests).

?

And I made 4 SSB contacts on 20 meters with some Italian stations in a contest setting ....

running about 75 watts with the QMX+ and my HR-50+ amplifier.? Worked great.

Thank you, Hans ... you are a wizard!

?

One glitch ... I cannot get VOX to work.? I'm using one of Erik Larsen's microphones, which

clearly works fine in PTT mode and sounds OK.? I set microphone gain using the built-in

Mic Test ... goes red on just the loudest peaks.? On USB, speaking into the microphone

apparently triggers the VOX,? but it then cycles on and off until I manage to get QMX+ mode

out of USB over to LSB.? LSB doesn't work at all ... speaking into the microphone does not

trigger VOX.

?

Input device is set to "External Microphone".? And I'm using TRS (stereo) 1/8" mini cable

between the microphone and the QMX+.

?

Any hints will be much appreciated!

?

Thanks -

?

Bruce K1FFX

?

?

No,? thank you.? I agree it will work, so it is up to Hans now ?

I fired up my QCX 20M for the first time in over a year.? I didn't tune the antenna.? I sent a few dits and dahs, then when I checked I was at 2:1.? I am not transmitting into a darn near 1:1 and only seeing about 1.3 watts.? I know the QDX is very sensitive to SWR.? is the QCX also, did I likely blow my finals?? or is there a alignment that may need to be done since it has been so long since it was powered up?

?

Bob

1_002 working well here. First DX QSOs last night - Auckland NZ to Portland OR and Italy!

Upgraded to the latest 1_02_000 firmware from the 1_01_003 beta with no issues yesterday.? Calibration ran fine.?

?

Today had the first QMX+ to QMX+ message exchange using the FreeDATA protocol, between Ohio and Maine on 20m.

?

What a great little radio!

?

-Dj

?

Thanks George for testing the internal mic yourself. The audio quality might not be the best in this way, but could be enough for making quick and short QSOs.

?

73,

Yoon KM6KJI

I bit the bullet and went back to the previous firmware version: xxx.027, without the SSB support. Sad to report that the RF output power has not changed - still about half of what it was before running that *&*^^%$ calibration procedure. I certainly won't be doing that ever again. :-(

?

Hans - any idea what has happened and how to resolve it?

?

I've got a handful of spare BS170 FETs in my parts box. Is it possible that the calibration thing clobbered one or two of the installed ones? What can I measure to check?

--

Jim / K7TXA
Eagle, ID

SKCC 10447T
BUG 301