Re: Help for QMX in Germany
resoldered the wire, but still no difference. Step 7 page 34.
If I hold a wire(end of a resistor for example) at any of the solder point, or the wire-bridge, the receiption and noisefloor improve.
73 de Harry, DK2GZ
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Re: Help for QMX in Germany
If i put my fingers, or touch the bridge with a paper clip, much more "noise" in the RX an weaker singals also a bit louder(just checked in 10112):
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Re: QMX and WKmini problem-Not sending after OS v 9...
QMX & WKmini Set Up
Terry
I am interested in how you handled the wiring set up?
Could you send a sketch of how your inserted the WKmini between the computer and WKmini module.
I have tried several set ups to no avail.
Mike
K2OI
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Re: Help for QMX in Germany
Hello
got the info.
It was build by the seller and is a Rev Lev 2 board.
IC407 is now replaced, also the diode protection is on now. See also my first post.
a) will check L401 and T401 now
d) a cracked capacitor C526---> I have output
73 de Harry
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I agree that a mid-band variant would be better for me as well. I already have one kit I assembled myself and am #10 on the list for another unit that is currently awaiting the GPS module. Once that gets here I may take my original kit and attempt any mods to make it mid-band.
I hate giving up on the 15 and 17 meter band.
For a digital-modes radio to not use more of the WARC bands where the predominant modes are CW or digital.; IDK.
10 and 11 don't mean much to me. I would happily give up on 80.
--
Tisha Hayes, AA4HA
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Re: Help for QMX in Germany
Harry, one more thing. If IC407 should become damaged, that could also create a deaf condition. That stereo ADC chip is the most vulnerable to overvoltage of all the chips on the 5V distribution. A failure there is often accompanied by heating of the chip. I note all that here for completeness, though I think your problem is elsewhere.
JZ
Harry,
I have seen the following cause a "deaf on all bands" condition:
In order of declining likelihood:
a) a bad connection at either L401 or T401. This is absolutely the first thing to check. Wire enamel can be difficult to properly remove.
b) a failed 3253 mux chip. There was a rash of this early on in Rev 2. It was corrected in Rev 3 with the addition of a diode. I have seen only one failure of a corrected board, and it was due to an open circuit created at L503, voiding the T/R switch function. Checking for the correct bias voltage of 2.5V at C406 is usually a good test for the mux.
c) a short at the BNC connector. This is not so easy to determine, as by design an ohmmeter will show a DC short at that point while all is OK for RF. Only close inspection can help.
c) a failed T/R switch transistor. Rare, but it has happened. With power off, an ohmmeter check of resistance from each terminal to every other terminal should yield very high resistances for a good transistor.
d) a cracked capacitor C526. This will generally be accompanied by zero output power.
GL JZ
May I have to ask the seller, if it was an assembled unit, I do not know.
But how about the general deaf RX on all bands?
Winding L401 a thought? Mine have the older winding.
73 de Harry, DK2GZ
?
?
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Re: Help for QMX in Germany
Harry,
I have seen the following cause a "deaf on all bands" condition:
In order of declining likelihood:
a) a bad connection at either L401 or T401. This is absolutely the first thing to check. Wire enamel can be difficult to properly remove.
b) a failed 3253 mux chip. There was a rash of this early on in Rev 2. It was corrected in Rev 3 with the addition of a diode. I have seen only one failure of a corrected board, and it was due to an open circuit created at L503, voiding the T/R switch function. Checking for the correct bias voltage of 2.5V at C406 is usually a good test for the mux.
c) a short at the BNC connector. This is not so easy to determine, as by design an ohmmeter will show a DC short at that point while all is OK for RF. Only close inspection can help.
c) a failed T/R switch transistor. Rare, but it has happened. With power off, an ohmmeter check of resistance from each terminal to every other terminal should yield very high resistances for a good transistor.
d) a cracked capacitor C526. This will generally be accompanied by zero output power.
GL JZ
May I have to ask the seller, if it was an assembled unit, I do not know.
But how about the general deaf RX on all bands?
Winding L401 a thought? Mine have the older winding.
73 de Harry, DK2GZ
?
?
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Re: Help for QMX in Germany
May I have to ask the seller, if it was an assembled unit, I do not know.
But how about the general deaf RX on all bands?
Winding L401 a thought? Mine have the older winding.
73 de Harry, DK2GZ
?
?
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Re: Help for QMX in Germany
A reading of 1310 Ohms (1.31KOhms) is plausible and makes much more sense.
Regarding capacitors, as the manual says on pages 24 and 25, capacitor color may be yellow or blue, depending on availability. If you can see and read the values printed on the caps (difficult!), do so. It is easy to make a placement mistake.
Do you know if this was a factory assembled unit?
JZ
Page 31:
if I checked in the "piep-mode" the value was 1310 not 1.310 between A and B.
About the capacitors placement.
I am still not sure about mine (look to the main board above here in the post). There are only two blue of them on mine.
I do not know abot the Rev level, bought it used, sorry.
73 de Harry, DK2GZ
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Marek, Thank you for the search idea. I don¡¯t know why I didn¡¯t think of that.? From what I read, that would be the best band combinations that I would prefer.? I¡¯m also planning on buying an assembled unit so I have to just decide if I want to wait or not.? Thanks again. Ken -K9ZI
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Show quoted text
On Mar 21, 2024, at 4:48?AM, Marek SP9TKW <sp9tkw@...> wrote:
?Ken,?
if you type mid-band in top-right corner search box, you will get several articles on the subject.
Hans has such version in his plans but not at the high priority, so in the mean time there are few conversions around being done. I am just in the middle of such project based on document prepared by Bill N6MTB. Search articles as I enclosed it in one of the posts.
I just had a first power up and my Rev.2 9V QMX is alive. Output power on 60-40 is 4.5W but other bands need some tuning.
---------------------------------
73 de Marek SP9TKW
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Re: Help for QMX in Germany
Page 31:
if I checked in the "piep-mode" the value was 1310 not 1.310 between A and B.
About the capacitors placement.
I am still not sure about mine (look to the main board above here in the post). There are only two blue of them on mine.
I do not know abot the Rev level, bought it used, sorry.
73 de Harry, DK2GZ
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Re: Help for QMX in Germany
Measurement is *not OK*. Page 31 is clear: there should be no connection between A and B. A reading of 1.31 ohms is almost a short circuit. Something is wrong.
What is the Rev level of your QMX?
The picture on page 27 (Rev 2, 3 manual) is showing the capacitor placement for a? 20m-10m unit.
Note the differences in highlighted capacitors, page 23 and 24.
JZ
Hello
did inspect the board now.
Checking page 31, measuring are o.k.
A<-->A connection(piep)
A<-->B 1.310 ohm
On my QMX the blue and organge Cs not on the same place as in the manual page 27.
The main problem is not the low output on 30 and 20 Meter.
The RX on all bands is a little deaf.
73 de Harry, DK2GZ
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Re: Help for QMX in Germany
Also according to page 43.
A, B, C and pin 9 of IC402 are all connected.(piep)
73 de Harry, DK2GZ
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Re: Help for QMX in Germany
Hello
did inspect the board now.
Checking page 31, measuring are o.k.
A<-->A connection(piep)
A<-->B 1.310 ohm
On my QMX the blue and organge Cs not on the same place as in the manual page 27.
The main problem is not the low output on 30 and 20 Meter.
The RX on all bands is a little deaf.
73 de Harry, DK2GZ
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Re: QMX 5V SMPS not working
Regarding the survival of the capacitor, I think the current limit and resulting boot loop saved it. I measured the capacity with my cheap LC meter, it showed 480uF, so all good.
All final checks with th QMX went well, fired it up, and was spotted by RBN, so I guess everything works.?
Let's see if I can activate a park with it next week on my holiday in 9A. :)
Agn mni tnx fer support, cu on the bands.
73 de OE3RLV Robert
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Ken,?
if you type mid-band in top-right corner search box, you will get several articles on the subject.
Hans has such version in his plans but not at the high priority, so in the mean time there are few conversions around being done. I am just in the middle of such project based on document prepared by Bill N6MTB. Search articles as I enclosed it in one of the posts.
I just had a first power up and my Rev.2 9V QMX is alive. Output power on 60-40 is 4.5W but other bands need some tuning.
---------------------------------
73 de Marek SP9TKW
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Re: QMX 5V SMPS not working
Was an easy fix, and the QMX started up, so its not necessary to send a new one.
Tnx!
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Re: #qdxm #QDX-M QDX-M, searching for information about coils and transformers winding data for 2200m and 630m
#qdxm
#QDX-M
Thanks for the proposal. But I do not want to use transverter, I want to be more compact and portable.?
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Re: QMX 5V SMPS not working
Hi Roebi
Yes, that capacitor is the wrong way around. First time I've ever seen that. Wow. I don't even know how that could happen because?the SMD factory is all automated and the capacitors come off a reel, where they are all the same way around. So either all 1,000 in the batch have to be wrong, or none of them. But I just checked loads here and they are all correct. Very strange...?
Also strange that if connected in reverse, it didn't just blow up...?
Do you want to try changing it around? Or shall I send you a new one??
Ok my measurements confirm C107 is wrong, D108 correct.
Anyway, can anybody confirm this please? And please also take a look if there are obvious other problems.
Mni tnx!
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Re: QMX 5V SMPS not working
Ok my measurements confirm C107 is wrong, D108 correct.
Anyway, can anybody confirm this please? And please also take a look if there are obvious other problems.
Mni tnx!
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Tisha Hayes, AA4HA
Marek SP9TKW