I have built a MMR-40 pocket size QRP 40 meter ham radio, it transmits between 5-7 watts but can reach around the world. It is one of the few tiny sets that does both sideband voice and morse code. I have stuck the FreqMite and NorCal keyer add on boards to add memory keyer and audio frequency reporting outputs. I have also added a earphone jack and will add a serial port for computer data. The whole field kit including the NorCal BLT tuner, wire dipole, and feedline fits inside a Case Logic CD player bag.

I decided to switch to a paddles setup for camping, which to me is easier than a straight Morse code key away from a desk. THe cheapest I could find a paddles set was $25, so why not try to make my own.

I visited a Jerusalem hardware store and decided basic nuts and bolts would be the easiest. Two cut off stainless steel rulers two cm wide were the basis of the paddles, they are mounted to a pressed board base with small 90 degree steel brackets. A second set of brackets holds the swing adjust screws which are just two machine screws held in with regular hex nuts. Between the paddles is a larger stainless machine screw which is the common ground, electrical contact is against the round screw head. Two small stainless machine screws are the electrical contact points on the paddles, these screws also hold about 4cm of scavenged kitchen counter edge panneling rounded off to make for a more comfortable finger contact area. I used a chopped off earphone cord for the connector, soldered the wire into some solid copper wire which connected to the paddles where they attached at the far end between the bolt and a washer, the center pole was also just a wire wrap and compressed between two washers. To protect everything I sandwiched the wires between a second piece of press board and added rubber feet for use on solid surfaces.

Labels: DIY, ham radio, morse code, QRP

  ¶ 8:44 AM