Topband: Building a practical vertical from Al tubing

[ac7a@cox.net]

Hello Topbanders,

My current 160 meter antenna, a 45’ top loaded affair, has served me pretty well, but I wish to replace it with something taller; preferably, for aesthetic reasons, one not involving a tower. I think for my urban lot a reasonable height limit is probably about 75’. One of the European verticals probably isn’t a realistic option for me, so that has left me pondering a homemade vertical antenna, which would be constructed of aluminum tubing from the common amateur radio sources. I’d love to use irrigation pipe, but I don’t find any distributors listed in the local yellow pages. So that may not be an option for me. Also, I am not sure how I one goes about transporting the pipe to their house?

A few years ago, a ham on the list sent me his design for a 70’ vertical built from 6’ or 8’ tubing sections. The base sections started with something like 2 ¼” tubing and were progressively smaller in diameter to the top. It must have been a challenge to erect the lengthy noodle, but he said he had built and phased 2 of them together. I never asked him, but I suspect he used a gin pole to orient them vertical.

Although I had the usual ME classes in college years ago, I only have a general feeling for what constitutes practical diameters and lengths for the vertical sections. I’ve thought about starting with three, 6’ sections of 2 ½” tubing, coupled together using smaller internal pieces of tubing and then following that with progressively smaller diameter sections. Like my current vertical, I plan to use a wire capacity hat to top load the antenna. Therefore, the upper sections would have to support the wire weight.

If you have experience successfully building such an antenna I would appreciate hearing how you did it - and of any pitfalls you encountered!

Thanks & ’73, Thomas – AC7A