Continuing the saga of my homebrew direct conversion receiver, I rebuilt it on copper clad with some minor changes. I added an LM317T voltage regulator so I could power the RF amp and audio amp with 12 volts while the arduino and mixer can be powered with 5 volts.
I ran into some problems with the regulator and while I was measuring the output, a slip of the DMM probe sent 12 volts into the arduino, popping one of the capacitors on its internal regulator.
After messing around with it and replacing the blown cap, I still couldn’t get the arduino back in working order, so I just ordered another batch of pro minis to replace it.
Once I got the replacement pro mini loaded up and on the board, I found that the screen wasn’t working. I figured it was blown as well and replaced it with another 16×2 lcd. (I later found out that the screen was fine. It must have been a loose connection or something.)
Now that my vfo was working, I was able to solder everything together in a big frankenstein board and power it up.
The audio amp worked much better than the lm386 from the last post, but in this configuration, I was getting overwhelmed with the holy roller shortwave broadcasts. I added a band pass filter that knocked it down a little, but not much. Either the filter is too wide or I am picking up the station on some of the leads on the board. In my next post, I’ll most likely rebuild that filter and see if that helps any. Then hopefully I can get this monster in a case.