I started building up the RockMite 20 m CW transceiver yesterday. This is a great little kit and a great little project. I've been working in the logic design industry for the last fourteen years on projects like the Pentium, and the K5 and K6 processors. My part of these projects was done completely in simulation. Consequently, I haven't built a real board project in all that time. So, even though I suppose it should seem commonplace to me, I'm floored that for about $25 you can get a radio with an integrated receiver, transmitter, and a micro-controller that all fits on a board that's maybe 3" x 2"! The first component I installed was the NXP SA612A double balanced mixer and oscillator shown below. Here's the datasheet for this little guy [pdf]. It's used in the receiver section to strip the carrier from the received RF signal leaving only the audio to be amplified and sent to the headphones. You can read more about the heterodyne and demodu...