Thank you Stan,

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This is so obvious I am not sure why I did not think about it!

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Sure, I loose autonomy but I will get my 5W till the end. I just hope that it isn't going to be noisy (was my thinking behind the linear regulator).

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73,

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Yannig - F4IUJ

Hello Alan,

thank you for the quick answer.?

I did the search for bad soldering already. Without finding anything.?
I kind of know how to solder but I don¡¯t know how to find a problem on a board.?

So I think I¡¯ve produced about 100,-€ of garbage, I¡¯m afraid ?.?
73 and merry Christmas?

Rico, DG5BQ

It would just shut down. I would have to disconnect the power to get it to reset. ?In the case no problem. I was testing the RF power output on all bands. Just the normal cables connected between the rig and various RF output meters with a dummy load attached to it, morse key, battery and Drok voltage controller set at 11.9 v.

In the case it seems to work as the manual says. Power out was between 4 w on 40 meters and 5 w on other bands. 6 w on 160 and 80 meters.?

Hi John,

Glad you're nearly sorted. I don't use sma fittings on the relay board, I just solder coax direct, there are 3 large pads next to the sma placement. It also allows plenty of clearance should a gps board be fitted to the stack.

Andy

--

The universe is made up of Protons, Neutrons, Electrons but contains only one M0RON.

Hello experts ?

I just finished my build of the QMX 10-20m. During the first tests I found that the device is absolutely deaf on all bands. Measuring the board I figured that I have a short over all contacts of the antenna jack. I removed the jack. But still I do have continuity over all connection point.

Does anyone have an idea where to look next?

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Vy73 de Rico, DG5BQ

Just received my qmx 20-10 ... really the best Xmas gift ever ?

thanks Hans and team, wish a very nice Xmas and a happy new year....?

vy 73 de Udo DF4BJ?

I use a talent cell 12/3000 without any problems... in home shack I use the loading adapter of this powerbank.. works great since months

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vy 73 de Udo DF4BJ?

Hi Roland,

Is the resistance between R2/R3 and D1 still ¡°zero¡± after you have reinstalled C3? If so, as suggested by Evan, please check if there is any solder bridge/whisker. Please check both sides of the PCB. A whisker can be very thin.

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There should not be a short there. If no bridge/whisker, then (1) either R2 and or R3, and (2) BS170 at Q6 need to fail as short circuit to create that status, I think. Is the resistance from R2/R3 to GND about 21.0 ohms?

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Hi Evan,

Thank you for stepping in. I really appreciate it. This gentleman¡¯s amp worked fine one day (25W at 14V), but no output the next. His troubleshooting found incorrect voltages at L10, R13, the first step after checking of supply and 5V regulator voltages in the NA5Y¡¯s video. We traced it to abnormal resistance at C3 and are stuck there now.

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73 de Aki, JO4MTH

Thanks Nick. How many PA transistors do you have? I thought I'd fitted three in mine but I see there's only one. I bought extra BS170s at the time.

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I'm now looking at housing the transmitter. I fitted a right-angle SMA socket last night so now it won't fit the original box. If I'm changing to a bigger box it opens up more possibilities; antenna switching relay, relay-switched attenuator, bigger front panel and so on. I'll feed the box from the station power supply or its own 12v supply and have linear regulators in the box for 5v and perhaps 8v or 9v for the PA.

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Turning the assembly over (yet again) last night I ripped the ground pad off the board. The corner mounting holes are plated through and at ground, so I'll use one of those in future.

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73,

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John G4EDX

I killed my QDX running off of a fully charged lifepo4.?
?Reached out to Jeff and now I have a working QDX again.?

Awesome work Jeff.?

thanks?

--

73s,
AA6ST
Sameer

I had a similar temperature-related issue with my QMX.? It would have loud 'digital' noise for several seconds, then be perfect.? And I took it out on a POTA activation, and the noise lasted longer at startup, then was fine.? But after the sun went down and it got cold outside, the noise returned and didn't go away, and I had to qrt.

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Such noise can be caused by a cold solder joint somewhere.? So at home I took the bottom cover off, and turned it on and let it warm up to proper operation.? Then I tested it a bit by using canned air to briefly spray different parts of the bottom of the circuit card, hoping to find the location of a cold solder joint by getting it cold. [Canned air is very cold when it first comes out; at work we used to use a freeze spray for this purpose].? When I sprayed the PCM1804 chip, the noise immediately returned, and it would go away quickly if I warmed it up with a hot air gun (set to a moderately low heat).? I repeated this several times, trying to reduce the area I was cooling/heating to determine the source of the error.?? After a few tests, I could cause the noise to come with a short blast of air right on the PCM1804, and it would go away again if I touched the chip with my finger for a few seconds to warm it back up.? So in this case indeed it was the PCM1804 chip.? I replaced it, and the problem completely disappeared.

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After I replaced the chip, I realized that I never tried to just reflow the solder on it, in case one of the pins had a cold solder joint.? I should have done that, so I don't really know whether it was a failed chip or a soldering issue.? Could have been either thing.

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Stan KC7XE

Surprisingly enough, Ikea makes some decent cables.?

Those 1956 eyeballs still have lotsa miles left in them. But after 11PM they seem to go a bit haywire.

--

Jim

VE4BWG

Essager is good brand with good quality for the price. Combine it with usb isolator modul and you are safe.

On Mon, Dec 23, 2024 at 12:41 PM, David Wilcox K8WPE wrote:

You might want to cover the inside of the case with copper foil

No RFI problems both in or out at my shack at current setup. Power is low enough, all ground loops eliminated, usb isolated, single point grounding, coax cables cut to lenght to avoid any accidental resonace with used bands. Noise that i have are mostly the things everyone living in the city have and we cant help it.?

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Good idea for anyone who is willing to try copper tape or similar just for the piece of mind.

Having the same issue. Got it working for several days straight. Then turned it on a few days later and it can't find the microphone again!

Some more on the QMX mid band high noise.

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First let me describe the issue. Turn on the QMX. Very loud static/noise. After about 10 seconds, the noise becomes intermittent, and then goes away entirely.? At that point the QMX works perfectly.? The noise is about 20 dB louder than the ambient band noise. Until today, I was just going to live with it.

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Today, I did a SOTA activation with my QMX. The noise continued for several minutes. I thought, uh-oh, I'm screwed. The noise then stopped, and all was well. I did a few on/off cycles to see what would happen. The noise would last about 10 seconds.? There is one key difference between today, and all previous uses of the QMX. The QMX was in my backpack for about 2 hours. The outdoor temperature was 45-50 degrees. This is the coldest I have used the QMX.

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Questions:

1) Is this the same noise others have been hearing ?

2) Has anyone found it to be something other than the PCM1804 ?

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73,

Steve, N2IC