Did something break, and what should I check?


I'd been having some trouble receiving SSB signals on my µBITX that my old Grundig YB400PE receiver was picking up (My QTH is really radio-noisy.  Really, really noisy. I'm right next to a freeway and across a hospital in San Francisco), so I've mostly started experimenting with digital modes while I learn the quirks of the v5 µBITX (and the CEC 1.200 firmware I put on it) before moving on to some antenna improvement work.   I'd made a few successful tests and my first contact (FT8) on the µBITX a couple days ago using audible connections (meaning, "Play the audio out of the speaker into the computer's mic, and hold the radio mic over the computer's output") on 20m.

So yesterday, I finally got all the connections I needed (and time to fiddle) to connect the radio properly via a USB audio input.  Hooray!  I made a few actual contacts, and my signal was definitely getting out according to pskreporter.info .  I then started playing with WSPR (using WSJT-X).  I was getting out pretty wide  (spots from over 11000km away!  wow.), but  I never actually *received* any WSPR transmissions.  Huh.  (To be clear, I was able to receive FT8, though it felt like others could hear me better than I could hear them)  I didn't think too much of it - never played with WSPR before yesterday, and I'm definitely still learning how it should behave.  Before turning in for the night, I set things so WSPR was transmitting and receiving so I could learn a little more in the morning.  This morning, however, no new spots all night.  None, when I had been getting a bunch earlier.  Hmm.

The µBITX seems to definitely be transmitting - it draws from 15-19 watts when doing so (same as when it was "working"), and I can hear myself on the Grunding YB400PE when transmitting into a dummy load, and I hear the FT8 I've been trying to transmit this morning.  To my ear, however, the signal sounds... weird.  The FT8 sounds are not as sine-wave-y as I'd expect, and my voice on the SSB tests seem a little muddy.   The antenna is still connected (first thing I checked), so I'm at a loss why I was getting such good reports yesterday and NONE overnight and today.   Does anyone have any suggestions of tests to do to isolate a specific problem?  I have multimeters, an oscilloscope, and a function generator, but not much else in the way of test gear.  Halp!

This was going to be my first actual weekend of playing with this radio - I'd love any suggestions to help me salvage it!


Join BITX20@groups.io to automatically receive all group messages.