4 July 2019 – This year’s club project

Richard, G3NII explained the main purpose of the latest club project, an HF choke, is to stop common mode currents flowing on the outer skin of coax feeder thereby stopping radiation from the feeder, stopping RF from getting back into the shack and also to lessen QRM pick up on the coax feeder. Thoughts of where if should be placed indicated that since this was adding impedance to the circuit, then positioning in the shack would be worth considering – BUT, make sure the feeder is not an odd number of 1/4 wavelengths long, any number of 1/2 wavelengths long would be ideal.

Richard pointed out that the project required 12 turns of coax on the toroid. You have the choice of 5 turns then cross-over then 6 turns, alternatively 6 turns then cross-over then 5 turns. The cross-over counts as one more turn.

The kits, which included all materials required, including the box,  were handed out and members started the winding and fixing. The evening ended with a Q&A session about the choke and other antenna configurations.

The kits were supplied to members only

Winding details