Re: New QMX Rev3 build - no power out...
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For what it¡¯s worth, my mistake was AFTER probing the pads I clipped a little bit off a few of the connections with the diagonal cutters. Probing should have been the LAST step! ? 73, -Lloyd (wa4efs) ?
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From: [email protected] [mailto:[email protected]] On Behalf Of C R Murrell via groups.io
Sent: Saturday, March 23, 2024 10:07 AM
To: [email protected]; [email protected]
Subject: Re: [QRPLabs] New QMX Rev3 build - no power out...? The "52 Tips" video by Hans does specifically call out doing continuity checks by probing? the pad rather than the component lead wire. ?
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On Saturday, March 23, 2024 at 07:48:40 AM CDT, Greg McCain via groups.io <gamccain50@...> wrote: Hi Mike, Did you do continuity checks on all the toroids by making sure you were probing on the pads of the wire ends or the sides of the solder fillet beads and not the actual wire ends that may be sticking up through the solder fillets? There weren't any specific instructions to do checks? ?in the assembly manual for T507, but you should see 0 ohms between each of the 4 pairs, A-A, B-B, C-C, and? D-D.? ? ? On Sat, Mar 23, 2024 at 12:49 AM, Michael LaBlanc Fellow QRP'ers,
I just completed a rev 3 QMX build.? I am VERY impressed with level of sophistication of this very small piece of kit.
I'm afraid I have made an error in my assembly and I need to ask this forum for a bit of help in sorting it out.
I am happy to say that I was able to flash the firmware and boot up the radio without a problem.? Also, when attached to an antenna I can clearly hear the sounds from the FT8 frequencies (my unit is the 20-10m model) so the receive parts of the circuit seem like they are functioning.? I am also able to connect to WSJT-X and get good decodes at least on 20m (the other bands may have little traffic right now).
However, I have no power output on the transmit side.? I will attach screen shots from the SWR sweep menu utility, but the measurements are erratic and VERY high (all run on a dummy load capable of 25W).? Also, when I go into the Diagnostics screen and press the "t" button, I get 0 power out, about 9.5 volts and the SWR bounces around between 6 and 10.? This behavior is similar on all bands.
My initial theory is that I have somehow messed up the SWR transformer (T507) and this is causing the high SWR protection software to keep the radio from producing any output.? Before I break out the soldering iron again to pull T507 out of circuit and possibly rewire it, I wanted to get some feedback from those with more experience ?
Thank you in advance for any ideas for further troubleshooting steps or alternate theories about what I have done wrong.
73
Mike
KC2EHR
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