Friday, February 3, 2012
Winter Field Day 30 - 10 Meter Loop
The main loop is made of 1/4 inch annealed copper tube 8.51 feet long. Half inch pipe would have been better but quarter inch was easier to work .. and it was what I had. Both ends of the loop terminate at the tuning capacitor with soldered connections for the lowest loss possible.
The coupling loop has a circumference that is 1/5 that of the main loop. In this case it is 1.7 feet. It is located opposite the tuning capacitor and can be moved or squashed slightly to adjust for best SWR.
The one improvement that immediately comes to mind would be to terminate the connection to the coupling loop in a SO-239 connector rather than the short length of coax I used.
A short length of heavy wire is used to connect one side of the tuning capacitor to the loop, the other was bolted and soldered to the body of the capacitor. As the tuning cap had been sitting for several decades a shot of Deoxit restored the connection between sliding contacts after I noticed that tuning was erratic while using an antenna analyser.
The supports for the loop are made from the ham's best friends : white pvc pipe and zip ties. Holes were drilled to keep parts from moving.