Just as an end to this, in case anyone does a search, gets the same symptoms, and wonders how it went:
Turns out I also had a tiny solder bridge between ground on the BNC socket, and the hole for RF on a SMA connector.
Fixed that, messed with Win11/WSJT settings a few times, disabled something called "allow an application to take exclusive control" buried deep in a config screen, that might have been critical, and made my first QSO (1400 miles with a garden fence EFHW at R-10, so it's not pulling any punches...).
I'll put the case back on, and do a proper check over all the various bands/etc, a little later, but for now, success!?
Thanks to Evan, Steve, Hans, and the community. Been building myself up to this project for a couple of months, and I'm well chuffed now!
73 Tom? M7EUT
On Mon, Dec 11, 2023 at 10:29?PM Tom Garnett via <garnett.tom= [email protected]> wrote: Back home, and I've made some progress - but I'm not there yet...
Re-flowed solder to all LPF toroids and also T401+L401, verified continuity to the 9 points that are correct for rev2. No way to verify correctness of T401, alas - but I'm sure I triple-checked it when installing.?
Repeated hardware tests, still no joy on any band. Set to receive on a resonant antenna at 40m, and was getting... well... *some* reception, but nothing like the usual FT8 moans. Put a DVM on the diodes, and got the expected values from all 6 (40mv on D509 and D512, 8v on the rest (built a 9v version, running with 9v input by this point).
One interesting oddity - the *first* time I ran any AF or Image test on a band, it failed (or rather, ran but gave very poor results), then if I tuned up or down a band, and back again, it worked, as did every subsequent test before I exited back to menu.
Tried a factory reset, as per Steve's suggestion... and the hardware tests all suddenly worked! (RF values aren't amazing at 80m, but hey, problem for later...)
Hooked up to WSJT in a fit of optimism, and I've got CAT control, but I'm not getting any audio into my tablet (which I assume is a configuration problem), and I also can't get anything that sounds like more than the vaguest suggestion of FT8 noise out of the headphone socket either. DIGI mode not CW mode. I'm also getting a tested SWR of 5 from a dummy load, and from an antenna I'm pretty sure is resonant.
So... yeah. Going to go over all the connections around the general area of the RF connections next, see if I've got a bad solder joint around there somewhere - but I mostly wanted to give feedback on the RF sweep issue, mention the weird symptom with failing the first sweep, and say that the factory reset turned out to be a significant help.
Cheers for your help so far, and I'll keep you posted!
73 Tom M7EUT
On Fri, Dec 8, 2023 at 12:16?AM Steve Beckman < n3sb@...> wrote: Hi Tom;
Try a software reset.
73, Steve, N3SB?
-------- Original message -------- Date: 12/7/23 2:26 PM (GMT-05:00) Subject: [QRPLabs] QMX - all RF filter sweeps bad, no continuity from IC402 to T401
Hi, first time building something as complex as this, very much pushing my limits here.
?
I've built and powered up a QMX - rev 2 - firmware loaded,?screen and controls operating fine, terminal access acquired, diagnostic screen looks okay when idle. Audio and image sweeps look good, but all 5 RF filter sweeps are just showing a line of noise around -60, which I'm pretty sure is bad.
Some of the comments on this group pointed me to the T401/L401 area, so I went back to those with a DVM, and noticed that when it comes to the continuity check on page 43 (end of section 2.13) I've got continuity between?all 6 A/B/C points, and over to pins 7 and 9 on IC403, as expected, but I do *not* have continuity to pin 7 on IC402.
?
I rather hope that will let someone suggest where I might look for bad joints/components, since I can't for the life of me figure out from any of the diagrams how it might be *supposed* to have continuity there!
(Looking again at the schematic, I can see that it "ought" to have continuity with pin 9 of IC402, and testing that with a DVM, it does.)
?
73
Tom
M7EUT
|
