开云体育

Hi Everyone,

I just built a 20/17/15/12/11/10 QMX kit (Rev 3, shipped after February 2024).? The good news is that it boots up perfectly, installs firmware, and interacts with PuTTy on my Windows laptop.? Whew.

The so-so news is that when I start it up without tuning to a station the audio is a bit scratchy and more white noise than it should have.

The bad news is when I hook it up with a 50 ohm QRP Labs dummy load, I get nothing for voltage when I check across the dummy load.? I know the dummy load works fine because I get good voltage with it on my QCX+ I built.

I checked the BNC connector, the center terminal (+) has continuity with the outside of the connect (ground)(-).? That can't be good.? I checked the solder connections, it looks good there.? And there is a decent gap between the BNC connector and the PCB.

Just for fun, I ran diagnostics on the laptop.? I see 7.9 Watts for power when I transmit in the terminal mode.? The LPF sweep looks fairly normal as far as I can tell, the rest of the sweeps look bad.? I uploaded the images to my cloud storage website:?

I double-checked T501 (RWTST), and I get proper A-A-A and B-B continuity, but not A-B continuity (normal indication)(page 31 of assembly manual).? I reviewed the instructions for the RWTST, and I really do believe I built this correctly.

I checked L401 for continuity as described on page 37, this checks good.? T401 gets proper continuity as described on page 43.

I spent about 3 hours under a digital microscope looking for solder shorts, etc.? I am using Kester 44 0.020" RMA 63/37 with a Weller WE1010NA 70W set at 725F with ETS 1/64" fine tip.

Any ideas for further troubleshooting?? Thanks!

73, Frank Goeddeke
K8FXG

Hi All,

I think I found the problem.? I believe I would T507 incorrectly, I get continuity on 6 of the wires together and on the other two wires together.? The instructions on page 44 say to wind the 0.6mm wire "ONE time through the hole".? I was previously under the impression that one time through means one time through.? But if we want a B-B wire as in the hole locations as in PCB diagram on page 44, that is technically TWO times through the hole, although I would probably describe it as ONE AND A HALF times through the hole.? I removed the T507 and will re-wind and re-install, I bet that solves at least one of my problems, the center pin on the BNC connector having continuity with the ground.? Once that is solved I'll re-check and see if other problems persist.

By the way, I forgot to mention in my original post I am using a 12V battery, it was measured at 11.9V when I started.

Thanks!? 73,

Frank
K8FXG