Robbie builds a Pixie 2 Transceiver
First, I would like to thank K9TIE (Frank) for supplying me with the XTALs for this project. He also sent me some cool pictures of his friend's antenna that was being erected. I've been talking with Frank for quite some time about programming microcontrollers, and we somehow got on the topic of amateur radios. He has given me a quite a bit of inspiration to get into the amateur radio hobby.
This project was really easy. The part that took the longest was making the circuit board. I hadn't used my CNC router in a while, so I forgot what to do. I also didn't have Eagle installed on that particular computer, and I had some strange settings that ruined my first two boards. It was related to tool changes, and resulted in the router dragging a bit across the face of the circuit boards, which wouldn't have been so bad except that it cut a few traces. Since this was an RF product, I decided to scrap it instead of just making a jumper.
My final board also had a mistake, but I didn't notice it until I had most of the parts soldered. I didn't have a trace from the capacitor divider to the emitter of the first transistor. This has been fixed in the current board and PDF files. I used a screw driver to scrape a trace on my board.
Step one of this project is to find a circuit board. I use mechanically etched PCBs, but you can use toner transfer and chemical etched PCBs, order PCBs from a manufacturer, or you could use perfboard or other prototype board. If you choose to use prototype board, it would be wise to mark a layout before beginning.
The next step is to solder the parts to the board. If you use my board layout, just follow the PDF for parts positions. I found that even though I drew the boards up I still had to cross reference with the schematic. That's how I discovered the mistake in my PCB.
Once the parts are soldered to the PCB, you need to find a layout position in your project box. I used an Altoids can, and my layout is a little tight since my PCB is a little larger than others that I've seen. I made it work, though, and I am happy with it. Do a dry layout before punching your first hole. Make sure that everything will fit. There's nothing more aggravating than when you drill a few holes to find that a switch bumps into a capacitor.
If everything fits, drill your holes. Then fit the parts in and complete the circuit. Once all of the connections are made, you should be ready to operate. Assuming you already have an antenna, headphones, and a key, you can begin testing your Pixie2. I had to make an antenna, and I used a piece of coax and two 25' phone cords. I stripped the ends of my phone cords and soldered all the wires together to make one big wire. Then I used heat shrink to seal the ends. I used two pieces of wire to connect my key to a 1/8" phone plug.
- I used female SIP headers for the LM386, the XTAL, and the L3 inductor. This gives me the option of trying out different configurations.
- I did not use a stereo jack for the headphones
- I think that the LM386 better drives an 8ohm load than a pair of headphones
- Someday, the bullet before this one should be tested
- BOM - Jameco is listed, but unfortunately at build time they did not have two parts.