Quadrifilar wound toroids (and Coax Cable stub filters)

quadrifilar wound toroidJames (M3YOM) has just emailed me after discovering something worse than fitting 90 or so PL259s last week; it’s winding quadrifilar wound toroids. Pictured is a completed L1 winding for the 40m filter. He says that it’s a T130-0 core with 7 quadrifilar windings which should give around 3.96uH and there are two in the filter box he’s making from a kit supplied by Bob Henderson.

Since James took on the job of producing a fully filtered Multi-Two station, he’s soldered nearly 100 PL259s and not one of them was faulty on the day. Good job OM!

James, the wire looks like that stuff we made the MegLoop with, is it?

James says:

“It’s not the megaloop wire, the Lo-Z winding (yellow wire) is 1.25mm solderable enamelled wire and the Hi-Z winding (Red wire) is 1mm solderable enamelled wire. The enamel is designed to burn away at low temperature so you can solder it directly without the need for striping it back first.

Incidentally, Bob’s callsign is 5B4AGN (he used to be a G3 before he moved) “

Bob, I’m sorry you used to be a G3. You should know that I’m forever poking serious fun at G3s, as they poke fun at M3s. Maybe you and I can form a truce and make the world a happier place?

73 all, particularly my new G3 friends.