I was looking through some old PW “Antennas to Go” suppliments and noticed the W3EDP antenna. This looks promising for SOTA use and I am thinking of trying it. To save time (I’ve got to knock up a tuner by Wednesday as I’m heading for the Gower on Thursday if the WX is OK) has anybody tried this and if so what is the best length for the counterpoise on 5 megs?
Not used a W3EDP “in the field”, but it’s what I’ve used for my home HF aerial for a good many years and it seems to do very well on 5 megs. I use the “standard” 84’ top with 17’ counterpoise draped round the shack. Make up a tuner using the original arrangement of a parallel tuned circuit and link coil - seems to work much better than trying to use a T-match or similar ATU, as some do. For 5 megs I use a 26 turn coil about 75mm long on a 50mm dia. former, tuned by a 250pF variable and with a 5 turn link over the cold end - you might want to scale that down for portable use! (Don’t know what the PW article says, so if this is gibberish let me know and I’ll try and send you more detail!)
In reply to G4MD:
Thanks, Paul, it will be useful not having to switch counterpoises for 5 megs. The PW article emphasises that a small value of capacitance gives the best result, which will help keep the size down. I already have a suitable coil - it’s even silver plated courtesy of the WD! - so construction should be fairly painless.
It’s always worth consulting the Cebik antenna site. Since Cebik died a few months back the site has changed and you now have to register. However, registration is free. http://www.cebik.com