Progress continues on my WSPR direct conversion receiver. The Colpitts oscillator is working nicely and is very stable. Yesterday I glued an SBL-3 diode ring to the board and hooked it up. With my ‘scope and sig generator I can see it turning 30 meter RF into audio. So far so good.
Now it is time to build the AF amp. Here’s my question: How many db do I need? The standard 100 db DC RX AF Amp seems like a bit of overkill — this thing won’t drive a speaker or a headphone, but instead, a computer soundcard. What do you guys think? How many db?
