My weekend project: Ultra-simple W1AW Receiver
Okay, I’ve been wanting to actually do a little radio project for a while. So, instead of cleaning and organizing my home office some more, I decided to go ahead and tack something together. So, the project I settled on was N1TEV’s “Ultra Simple W1AW Reciever” from the May 1997 QST. I had most of the parts lying around, so I got a piece of copper clad and went to work.
Along the way I learned a few lessons:
- When I first assembled it, the LM386 did what comes naturally: sounded like a motorboat. In discussing it with the the people on the freenode #hamradio channel (thanks especially to Aegis) I moved the power supply cap directly to pin six on the LM386 and the motorboating ceased.
- I then hooked it an antenna, and was treated to a local FM broadcast station (106.7 FM). More discussions suggested that I could add a lowpass filter, but then I realized that I had forgotten to install the 1K emitter resistor for Q1. When I installed that, I stopped hearing the FM station.
- I can hear the oscillator running. As I adjust the regeneration, the background noise starts low, and gets louder like I’d expect. I can also hear the signal from my FT-817 with just a short antenna hooked up.
- As yet, I haven’t heard any live signals. Then again, I haven’t heard much on my FT-817 either, so maybe it’s just because there has been nothing to hear. W1AW broadcasts on 3.5815 Mhz, so I’ll hopefully get a chance to check it out tomorrow.
Using my RFSpace SDR-IQ receiver also shows the oscillator working:
This shows the oscillator at 3.5795, and as I adjusted the regeneration, it the frequency of the oscillator does shift. Interesting.
I’ll be testing it and playing with it some more over the next few days.