Joel,
I had a similar incident on a QRP Labs built QMX+. ?It had lower power output from the factory (3 watts or so which is within spec) and then it had no power output. ?I checked T501 and it didn’t look like the wires had taken up solder completely like I want to see. So I reheated that transformer with high heat and longer application. Now I have even higher power output. ?So trusting the soldering procedure to burn off the lacquer coating on the wire is a not so good an idea in my opinion. ?I would at least scrape some of the coating off before soldering. ?And apply more heat for a longer period of time to complete the connection. ?
Just my humble opinion, but with 65 years of learning from my mistakes my method works for me.?
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Be the REASON someone smiles today.
Dave K8WPE
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On Jan 2, 2025, at 7:48?PM, Joel Macneill via groups.io <joelmacneill1977@...> wrote:
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Hello Chris, hello Ludwig! Wow I've got some interesting news this evening. Those voltages that I said weren't present yesterday, are present today. I can't explain it but I set the radio up on the workbench again this evening and confirmed that there was no voltage at t401 like yesterday, but I did have voltage this evening. And I have the voltage that I need at pins 7 and 9 of IC 403 and at pin 9 of IC 402. I'm not quite sure how to explain this because I didn't do anything to it. When I noticed the voltages were there, I connected the antenna to the BNC and right away I heard a crackle in my headphones. Now I'm getting signal meter deflection and I'm listening to CW on 80 m. I'm going to listen to the other bands as well but I'm also going to go into the area where I last was yesterday and make absolutely sure I do not have a loose connection. Obviously when I was poking around with the meter, something happened. Maybe my trifilar coil could have an intermittent short? I don't know but I'm hoping to find out and I will let you all know. Thanks very much for all of your input!
73s
VY2KW
On Wed, Jan 1, 2025 at 06:14 PM, Joel Macneill wrote:
1) I have continuity from C526 to the anode of each 1N4007 diodes closest to the rear of the radio and from the cathode of?each.?
Joel, thank you very much for your wishes.
I don't understand the thing with the cathodes. To the anode is ok but to the cathode the same time?
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All the five points are related to the LPF section. If TX is working well the LPF section should be also ok.
IC408 pin#5 only has 2.5v. ?(idle receive)
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Sorry, my mistake. 2.5 V is ok.
IC402 pin#9 is 0v,?
IC403 pin#7 is ?0v, pin#9 is 0v
Like Chris wrote: 2.5 V from the voltage devider R401 R402 would be ok.
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IC402 pin#1 0v and pin#3 0v.?
Ok both connected to GND.
That voltage should also be present at the trifilar toroid coil. Perhaps I am not making sufficient connection there or perhaps it's a short?
Later you found this by yourselfe. I think no short. In case of a short it should be close to 0 V AND the same voltage across R402, C406. It's strange to find 0 V at all the three pins to C402 / C403. It means all three windings are affected. It looks like more than one bad connection and / or connecting the windings in a wrong way.
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I hope fixing T401 will be the solution.
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73 Ludwig
David Wilcox K8WPE