I’ve always had, what some people might call, antenna envy for an end-fed half-wave 20m vertical built by Peter G8BLS. It comprised a simple coil and capacitor housed inside an old fizzy drink bottle. On one end it had a connector for the wire antenna and at the other it has an SO-239 for the coax. It required no further tuner – what could be simpler? I wanted one.
In my library I have a copy of Stealth Antennas by Steve Nichols, G0KYA and on page 115 he talks about a mono band end-fed half-wave vertical built using a T200-2 toroid and fixed length of coaxial cable acting as a capacitor. I decided that this was the design for me although I’d replace the fixed capacitance with a variable capacitor.
The build is shown below. It was built into a cardboard box to allow easy access and if it didn’t work as expected then I’d could simply bin the box and recycle the parts.
I started off with the number of turns outlined in the book but found that it gave better performance, with the tuning mid-range on the capacitor (100pf), with two removed. I now have a simple 20m end-fed half-wave vertical antenna tuner that I’m confident in and have used many times. Tuning is a simple job of adjusting the capacitor for maximum noise and then fine tuning with a signal while looking for a dip in the SWR. I’ve never had to use a counterpoise.
I need to find a better box!