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Hi all
The QRP Labs QMX Multimode Multiband QRP transceiver kit is an amazing combination of performance, features and low price in a very compact package. We have at the time of this video production, assembled something like 60-70 QMX transceivers here at QRP Labs Towers. This video contains my observations of some common pitfalls to avoid, and tips for successful assembly.
Some of the 52 tips may be obvious to you, many are in the assembly manual (which of course you will read word to word, cover to cover); but I suspect the majority of constructors will find at least something useful in the video. QMX is a compact build. With care and attention to detail, you should achieve a functioning, high performance transceiver.
I also created a Playlist of official QMX videos (though there are lots of other QMX videos too):
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good afternoon Hans, I am enjoying watching your very informative and helpful video.? A thousand thanks. Giuseppe iu8eun
Hi all
The QRP Labs QMX Multimode Multiband QRP transceiver kit is an amazing combination of performance, features and low price in a very compact package. We have at the time of this video production, assembled something like 60-70 QMX transceivers here at QRP Labs Towers. This video contains my observations of some common pitfalls to avoid, and tips for successful assembly.
Some of the 52 tips may be obvious to you, many are in the assembly manual (which of course you will read word to word, cover to cover); but I suspect the majority of constructors will find at least something useful in the video. QMX is a compact build. With care and attention to detail, you should achieve a functioning, high performance transceiver.
I also created a Playlist of official QMX videos (though there are lots of other QMX videos too):
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Excellent video, Hans!
73, Randy, KS4L?
Hi all
The QRP Labs QMX Multimode Multiband QRP transceiver kit is an amazing combination of performance, features and low price in a very compact package. We have at the time of this video production, assembled something like 60-70 QMX transceivers here at QRP Labs Towers. This video contains my observations of some common pitfalls to avoid, and tips for successful assembly.
Some of the 52 tips may be obvious to you, many are in the assembly manual (which of course you will read word to word, cover to cover); but I suspect the majority of constructors will find at least something useful in the video. QMX is a compact build. With care and attention to detail, you should achieve a functioning, high performance transceiver.
I also created a Playlist of official QMX videos (though there are lots of other QMX videos too):
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Hans, I can add one tips:
When installing the input power connector, push it towards the board edge.
This will increase the very small clearance to the left encoder on the control board.
Nevertheless I put kapton tape on the encoder body facing the power connector
73 de SM5EIE /Gunnar
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I agree about pushing the power
connection to the board edge. I did that and there's enough
clearance not to need adding insulation.
Otherwise what I did was to wind the
toroids first and do a dry assembly of everything in the LPF area
to make sure that everything fitted.
Then solder everything more or less
from the outside in, finishing with the toroids.
A few other thoughts:-
When fitting the connectors between the
boards I fit the boards together with the connectors then solder a
couple of pins on each connector while fitted together so they jig
each other.
I squeezed the pins for the PSU boards
together slightly so they touched the board.
When soldering the BNC fit the display
and main boards together in the top of the case with the BNC
attached to the end plate and the plate fitted to the top half of
the case. Maybe the other end plate also fitted.? This holds the
BNC and main board in the correct orientation while you solder it.
Chris, G5CTH
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Hans, I can add one tips:
When installing the input power connector, push it towards the
board edge.
This will increase the very small clearance to the left encoder on
the control board.
Nevertheless I put kapton tape on the encoder body facing the
power connector
73 de SM5EIE /Gunnar
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Hello Hans,
Thank you for the excellent Video. I think I can use it for the building of the QMX, which arrived me yesterday without any problems.
Vy 73 de Dc4kjs?
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So to clarify - The manual at Rev H currently says to burn or drill out the center of the spacer nuts on the power board - That is no longer recommended according to the video?
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Hans says it’s best to do it as he shows in the video to keep the boards properly oriented. Looked really easy to do the way he demonstrated. It’s an ongoing process of finding the best solutions and updating the manual.?
Ron
So to clarify - The manual at Rev H currently says to burn or drill out the center of the spacer nuts on the power board - That is no longer recommended according to the video?
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Here we found it easier to achieve precise alignment of the SMPS boards if the spacer nuts are NOT drilled out. The reason is that drilling them out, or shoving a soldering iron through them, either way distorts the shape of the nut so it no longer sits precisely. This is based on experience trying both ways here. So I will update the manual to remove the bit about drilling out nuts.?
So to clarify - The manual at Rev H currently says to burn or drill out the center of the spacer nuts on the power board - That is no longer recommended according to the video?
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Here we found it easier to achieve precise alignment of the SMPS boards if the spacer nuts are NOT drilled out. The reason is that drilling them out, or shoving a soldering iron through them, either way distorts the shape of the nut so it no longer sits precisely. This is based on experience trying both ways here. So I will update the manual to remove the bit about drilling out nuts.?
73 Hans G0UPL
Now, you tell me! Har, har! No trouble here with reaming the threads but the method here is just as good and reduces one operation.
Watched/listened to 52 tips on the youtube link and all I can say is: GOOD SHOW! Very well done production and I have tennis elbow from patting my own back for getting several tips all by myself! The example was that BNC 90° just did not look straight and testing with the end plate before soldering confirmed it. That video will help all the next group of builders immensely.
73
Karl
KI4ZUQ
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Just one more comment on the excellent "52 tips for building your QMX successfully" youTube video: With regard to the BNC connector, if you test its output to ground, you will see a short even though there is no actual short on the BNC.? That's because T507, the VSWR Stockton bridge transformer, has a winding that goes directly from the output to ground.? Either just inspect the BNC connections carefully for any shorts or mount the BNC before mounting T507.? Note that the pad from the hot side of the alternate SMA pads is very close to one of the ground pads of the BNC so this is good to carefully inspect.
-Steve K1RF
------ Original Message ------
Date 8/27/2023 10:14:59 AM
Subject Re: [QRPLabs] #qmx video: 52 tips for building your QMX successfully
Hans says it’s best to do it as he shows in the video to keep the boards properly oriented. Looked really easy to do the way he demonstrated. It’s an ongoing process of finding the best solutions and updating the manual.?
Ron So to clarify - The manual at Rev H currently says to burn or drill out the center of the spacer nuts on the power board - That is no longer recommended according to the video?
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This was a challenging kit due to the density on the PCB, but the instructions were very thorough and I was able to complete it successfully. I've made a dozen or so QSOs with it and the performance is outstanding. I've been able to work stations up to 2,500 miles away. Amazing! Thank you for making this kit available.?
--
Marty Mueller, N7AAE
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Any video on QMX is a good video!
Thank you Hans, that you do this work.
( But you still have to work on your acting skills).
I had already written elsewhere. EVERYONE who proceeds normally carefully and adheres to the building instructions will have success.
I had bought a new side cutter to separate the wires just above the solder.
With the 0.6mm wires I have then applied to the fresh separation point again solder, so is in any case 100% contact.
Meanwhile, you can already see many pictures of finished soldered QMX boards, it strikes me that very often much too much solder is applied.
It is completely sufficient if the soldering eye is closed by the solder.
A solder hill over each soldering eye is not necessary.
The path is the goal! I also soldered this kit with pleasure.
The degree of prefabrication is high, you can take your time and it still goes fast.
Thanks again to Hans for putting so much work into the build documentation.
Greetings from Germany,
Axel, DL5GT
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The tip about not tightening the PA retaining screw too tightly due to a 5v trace running underneath it, triggered my inner doubt monster so I went back in and fitted a small mica shim under that screw head.?
Mine is built for 12v and, after a bit of toroid bothering, it puts out between 4.5 and 5 Watts on all bands.?
Another excellent kit and incredible value for money. Mine has already made CW contacts into Brazil from here in Scotland.?
Cheers,
Ronan
MM0IVR?
??
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Hi Axel,
Yes, a hill of solder is not necessary on a thru-hole solder joint. But your recommendation to just fill the hole is not sufficient. How do you know if there is wetting between the solder and the pin in the hole? The characteristic of a good quality thru-hole solder joint is that you can see a concave shaped minimum amount of solder wetting both, the PCB solder pad and the pin protruding the hole, on both sides of the PCB.
See also?
73 Jakob
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Randy
Stefan
Ronald Taylor
Karl