Yet Another G/WB Activation

In reply to MM0GYX:

Sorry missed it Ian. It all has to fit on a 5m pole which is why I don’t have a GP antenna. You need a 7m pole for a 20m GP, well maybe you can make something work on a smaller pole. So I copied the business parts of a Buddistick. I think the radiation section is about 11ft6 (sorry it was an American design so it came in old money measurements and I never converted them to metric!) including a 7 turn coil about 2-3ft up from the feed. The coil is used on 20m but for 17/15m it is shorted out. The counterpoise is probably 2ft off the ground and the lenth is varied to tune for 20/17/15m. I think it’s 25ft for 20m but I’d need to check. I have some tiewraps on the counterpoise marking the lengths.

At the far end I have two sections of tent pole to hole the counterpoise up. This is light but stiff. It folds in half and sits by the pole on the side of the rucksack for carrying. The end has a metal point which is good for pushing into the ground.

The only downside is it’s not an unroll and go antenna. I set it for what should be OK and have to check the match. This means tweaking the length of the counterpoise slightly. So it takes a few minutes to physically install and a few minutes of faffing. It’s more affected by ground on 20m that higher bands. It doesn’t like snow underneathe the counterpoise, that really throws it off tune. Also when I was on Madeira last October, the ground was so different to Scottish ground the tuning points were vastly different. I happened to have a few hours free one afternoon and went and setup the antenna and had a devil of a job finding the match points. But once I knew y how much I needed to shorten the counterpoise, I was able to go straight to a match on both summits I activated.

There’s an article on here about the antenna somewhere but I can’t find the link right now!

Andy
MM0FMF

In reply to MM0FMF:

You need a 7m pole for a 20m GP, well maybe
you can make something work on a smaller pole.

Maybe a 20m version of the VK7JJ squid pole would work.

http://www.perite.com/vk7jj/squidpoles.html

I’ve built one and it works well on 40m and other bands as noted. It requires a 9m pole which can be a bit big/heavy for the higher summits.

Colin G8TMV

In reply to MM0FMF:

Thanks for the info Andy, I’ll look into a vertical I think. Maybe in the summer time though, this time of the year it’s up and back down without faff if possible.

Ian MM0GYX

In reply to G8TMV:

That’s just an end fed half wave on 20m. So you need 10m of wire. And a 10m pole. Or 9m if you wind around the pole a bit. I guess you missed the bit where I said I only had a 5m pole. :wink: I used a 10m EFHW with some good results on 10m/12m & 15m before I mislaid the matching unit. They’re nice as you don’t need significant radial or counterpoise wires. I did have one on 20m but it was a pain to use due to its size. The match unit is probably on the top of Torlum Hill somewhere.

Andy
MM0FMF