Tuesday, May 16, 2023

Building another YU7EF duoband antenna (3)

   Slow progress is made. I wish I had this antenna ready before the ES season. But unfortunately it takes time to build and time is a precious thing. I can't help experimenting with this design as well. I had no angle aluminium to mount on the boom to fit the (6m) dipole elements on. So I thought of angled weather resistant plastic. Side effect is that it probabely prevents disturbance from the boom. I really don't know how much and of course I don't know how this plastic behaves over time. I decided to take the risk. The material is also used for cladding on buildings.

Of course this gave me a mechanical challenge. The plastic looks solid but it isn't. The outside is solid 1mm thick plastic but the inside is a kind of foam. When you mount it on the boom with the bolts and nuts, like I did, the long end will move downward along with the pressure of the nuts. I needed to invent something to push it back to a straight position. I used tiny pieces of angled aluminium for that and bend it up a little. It worked out very well so far. I could nicely tune the plastic parts till they were flat with the boom.

When writing this post I just thought about the plastic foam. I think I need to protect the sides with a rubber like coating. I have some liquid gasket material in stock. I think that would be perfect.

Update 18-5-2023

I abandon this experimental plastic dipole mount. I tried it today but it did not work out like I had thought. Searching for angled aluminium thick enough to use now.


VE9KK said...

Good morning Bas, very nice and professional looking job on the antenna. When making something from scratch it always seems that with each new idea or plan come a line up of challenges. Very good idea with the brackets for support. We have here liquid rubber tape which I use for many applications around the shack.
Looks good and waiting to see updates and how in the end it works.

PE4BAS, Bas said...

Tnx for the comment Mike. This is a antenna build for PB7Z Bernard. He's about 50km south of me. I will not have it in my tower myself. But have made one before and that one is working very well. ES season is already there and I should have my VHF beam into the tower soon. And finish this one for Bernard. See his tower here: https://cdn-bio.qrz.com/z/pb7z/IMG_20220629_114240_727.jpg. He is currently using a 3 element version. 73, Bas