Re: Release of version 1.2 of ABS solution for QMX+ (Automatic internal antenna tuner, internal battery and internal speaker with audio amp)
#ABS
#ATU
#PSU
#QMXplus
Stan ?
likely my fault , but?
I want to add my name to the ABS kit list for one kit
KC1TXA
Richard Perry
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I had believed that I had done this atlas once before , but don't't seem yo find a record of it.
Groups ?newly and dummy
regards Richard KC1TXA
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Pleased to advise?I?am now on air with the QDX. Was a solid 8 hour construction?job. Thankfully it fired up on the first go. Had a bit of trouble connecting with the PC...had to use the TS480 setting and 8 n1 to get a connection.. ? ? ? ? ? ? ? Couple of things I found useful...Got? receive audio out of my PC into headphones.....on Win 11 use the command line" mmsys.cpl " and tick "listen to this Device". ?I wanted an easy way to tune the receiver in order to do some general?coverage listening . I eventually found a very basic CAT tuner app called "Rig Resident". this is by UU0JC and was just what is needed to easily move around the bands and just outside?to listen to WWV or the CW beacons,?19mB shortwave etc. ?Thanks Hans.I am amazed once more ! ? ? ? ? ? ? ? ??
-- Rick Hill
VK6XT
Ph 0493 413 761
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Re: Using WSJT-X 27.7.0-rc8 "FYI"
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QCX + stopped transmitting
My QCX+ worked great for more than 2 years. It stopped transmitting step by step. Sometimes 1 Watt output , after switching off and on for a few seconds again 3 Watts (12.6V). Than only 0.5 Watt during transmission.?
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And now no output anymore. Sometimes the trx is switching of, when trying to transmit. I removed the 3 BS170 transistors .? Seems to be that there is one of the FEDs damaged . Im not shure, if my SN74AC00N is still ok.?
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I can still receive, no problem. After removing the 3 Transistors the trx is stable, even when pressing the key.?
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Values during trx without BS170 Pins of? SN74AC00N, DMV Measurement
Pin?
1? ? ? ? ? ? ? ?2.46V
2? ? ? ? ? ? ? ?2.46V
3? ? ? ? ? ? ? ?2.51V
4? ? ? ? ? ? ? ?1.71V
5? ? ? ? ? ? ? ?4.97V
6? ? ? ? ? ? ? ?2.46V
7? ? ? ? ? ? ? ?0V
8? ? ? ? ? ? ? ?2.46V
9? ? ? ? ? ? ? ?0.10V
10? ? ? ? ? ? ?1.71V
11? ? ? ? ? ? ?4.97V
12? ? ? ? ? ? ?0.02V
13? ? ? ? ? ? ?0.02V
14? ? ? ? ? ? ?4.98V
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Im not sure, if this values are good.?
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Any Idea ?
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72 de Matt, DL1SER
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? Yoon,
Thank you for your reply. ?I had some time to waste yesterday (my XYL was driving) and I found the key on sale at eBay and Amazon, between $22 and $28 USD depending on the little accessories.?
?I went to the reviews and there was only one review from a very dissatisfied owner. I added another review more positive.?
?It’s a neat little key for backpacking or just learning, well built for the cost, only has two adjustments so it’s easy to set up. Magnetic base so it will stick to many rigs. I own many keys from a low cost White Rook MK-44 plastic thingy (that I love and grab for testing something new…. No adjustments at all) up to expensive Begali ones but this little key works and if lost or something breaks one is not out much. ?I would recommend one for anybody’s go bag.
Dave K8WPE
PS ?Now I understand…… He who dies with the most toys has probably forgotten much what he has and why……. So true!
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On Feb 22, 2025, at 12:15?PM, Yoon KM6KJI via groups.io <yoonh.choi@...> wrote:
? On Sat, Feb 22, 2025 at 03:26 AM, David Wilcox K8WPE wrote:
Where did you get that neat key in this photo?
You can search QU-7025 to find it. It's cheap and not any fancy, but works. I added the guardrail to prevent the levers from being derailed accidentally.
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73,
Yoon KM6KJI
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Re: Any hope left for the repair of this ?
On Sun, Feb 23, 2025 at 07:43 AM, Daniel ZL2DTL wrote:
still a short between pin 7+8, and another crossing 10-13 remain.
Daniel, that's fine. Please check the schematics for IC407. Pin numbers 1 to 14 are going at the left side top down und 15 to 28 at the right side bottom-up. Pins 7, 8 and 10 to 13 are all connected to GND.
You should find also a GND at pin 23 and 27 and a connection between pin 6, 9 and 22 all connected to VCC via L402.
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73 Ludwig
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Re: Any hope left for the repair of this ?
Hi,?
Cleaned with flux/solder braid but still a short between pin 7+8, and another crossing 10-13 remain. I imagine this was damaged when the chip was removed and scratched the board. However, and do correct me if I am mistaken, all of these pins are just grounded anyways so it should not be problematic??
I've never seen a QMX in quite this state, every time I have previously replaced these chips they have arrived to me with no repair attempted and it is time consuming but not beyond my ability to change. This definitely threw me off seeing the damage on the board.?
Thanks for the help all.?
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Daniel ZL2DTL/ZL4YOTA?
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Re: Testing for a dead QMX board
I’m more than happy to fix this. ?I get rigs from all over the world to bring back to life. ?Tariffs and expensive postage is a pain. ?But at least it’s an option.
Also, I’ll be at Hamvention in Dayton most likely if that helps.
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--
73
Jeff Moore
W1NC
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Re: Any hope left for the repair of this ?
This can be fixed. ?The missing pad is no problem. ? Pin 21 has no connection. ?
Clean with flux and solder braid carefully. ?Inspect everything else under magnification and solder in a new pcm1804. ?This looks daunting but if you have good magnification and solder skills, it can be done. ?I’ve fixed far worse for other hams.
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good luck.
--
73
Jeff Moore
W1NC
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Re: QMX Mid-band L401 Mux allocation?
15M is BPF0
17/20M is BPF1
30M is BPF2
60/40M is BPF3
It's shown on page 78 of the 1_00_026 operations manual
72 de va3rr
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QMX Mid-band L401 Mux allocation?
I neglected to check enable lines while my radio was open. Does anyone happen to know which bands correspond to which IC402 inputs?
I know that 15/17/20 go to 0 or 1, and 30/40/60 go to 2 or 3. But in both cases that's three bands but only two inputs.
Sketch from the manual:
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Re: ABS for QMX+ v1.2 speaker issues
Stan,
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Thank you for taking the time to explain how to troubleshoot my speaker issue.? Following your instructions, I sampled pin(3) and pin(5) of the LM386 with my scope.? I don't have much experience using a scope, so this exercise was a good learning experience for me.
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I settled on setting the sidetone volume at 80 while using the speaker.? The volume is perfect with the case covers in place.? I set the sidetone volume at 50 when using my headphones.
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I am really enjoying the portability and flexibility having a QMX+ with an ATU, self-contained battery and speaker.
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Howard N8HO
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Stan,
Absolutely you can eliminate 6 m and put 20 m (or 15 m) by itself. I was more thinking Hans could add one more LPF space so you wouldn't have to eliminate a band. There certainly is PCB real estate to do that. However, I am not that worried about it. I am perfectly happy the way it is. A half (or less) S unit down is NBD. In fact, I often deliberately run my 12 V rigs at 9-10 V anyway.?
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73, Dan? NM3A
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Hi Yoon,
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I really like your design!
It always makes me feel nervous to see a long antenna attached directly to the rig (imagining the stress on the circuit board).
The boot and hat arrangement could be made very strong and easy/cheap to repair/replace if it breaks.
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73, Mike KK7ER
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T501 can be left as is, but I don't think we can use the primary center tap when going for CMCD.
Need two L502's to power the two sets of BS170 drains.
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From ?
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And this brings us to current-switching class D amplifiers. These actually?need?separate RF chokes that conduct a constant current over the RF cycle, and they?need?the drains?being completely decoupled from each other! So, using current-mode class D turns a very difficult design problem into a very easily implemented design feature!
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Jerry, KE7ER
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On Sat, Feb 22, 2025 at 10:33 AM, Jerry Gaffke wrote:
Could take the QMX+, redesign T501 and the LPF"s for CMCD with the tank placed out beyond T501.
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Re: Any hope left for the repair of this ?
Hello Daniel,
cleaning the existent pads using flux and desolder braid should be easy. Than check if the yellow capacitors are well connected, solder if not. (C431 looks like desolderd.) The ripped pad is for pin 21 and regarding to the schematics not connected to anything. So this should be no problem. Solder a new IC and it should be ok (if no other problem exists).
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73 Ludwig
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Any hope left for the repair of this ?
Got the unit of someone who attempted to replace IC407 on their own. The board isn’t looking great. Just wanted the opinions of potential repair people better than myself
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the unit still turns on but of course gets stuck at initialising audio
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Daniel ZL2DTL/ZL4YOTA?
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Matti,
Very unfortunate problems you are having. The voltages you measured with the button pressed show that you have something shorting in your QMX+, on both the Vcc and Vdd lines.? It is not easy to say exactly what is shorted without further measurements, but most commonly there are issues with connections and solder flakes.? Or something external.??
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And if you shorted your Vdd to Vcc while probing, if you didn't have a current limit of 250mA or less set on your power supply, you likely blew one of the protection diodes, probably D109.?
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But it is not accurate nor fair to blame these issues on the QMX+ v2 or v3 SMPS design. Shorting without a fuse or current limit would damage some component in almost any design, yes, even with linear regulators.
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Perhaps QMX+ should have been designed with a 250mA fuse on the Vdd line, then assembly or handing issues that cause shorts would blow the fuse rather than the protection diode - then instead of placing blame on a power supply design,? ?we would be looking for what is shorting and fix it.
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Also note that a double long-press of the power button shouldn't have caused any issue.? I have done that before without consequences. Similar with a very long press, which first powers down then powers back up.
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Stan KC7XE?
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That is another great idea.?
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Mark
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David Wilcox K8WPE
Daniel ZL2DTL
va3rr