Something that’s been bothering me

For a little while I’ve been pondering a problem on, or rather mostly off.

My SOTAbeams SB270 is a 2m & 70cm antenna that used a fairly unique way of holding the antenna elements. There are a set of elements for 2m and a set for 70cm. Each element had a hollow nylon cap head screw with a knurled end that was screwed into the plastic antenna boom. Unfortunately Richard can’t supply these as spares.

My SB270 is useful for, well SOTA, and the occasional VHF contest but what is makes up for in portability it lacks in gain. So I’ve thought about making a single boom version that covers 6m, 2m and 7ocm. The idea seems reasonable but the crucial aspect of mounting the antenna elements is a sticking point. Here’s a brief design brief.




1. Doesn’t need tools to assemble in the field

2. Must stay in place once installed

3. Must be easy to replicate (Just in case anyone else wants a go). So no need for specialist fabrication skills.

4. Must keep with the ‘elements live in the tube when not in use’ principle, So no big bulky parts

I have used standard pipe clamps and they get knocked about and blown around in our strong winds. Stauff type clamps need tools so they’re out. Some 3D printed parts are available on thingiverse but they look like they are for permanent installations or don’t really float my boat.

So, here’s the plea. Any ideas other than the one below?

The current thinking is to use some thicker walled ABS pipe (like durapipe which is cheap and easily found) and some threaded inserts for the parasitic elements. Only feeding the driven element is making me think a bit. May need a cut out or permanent part which has feeder and (ugly) balun.

Thinking caps on!


Alex Hill, G7KSE, is a regular contributor to and writes from Cumbria, UK. Contact him at [email protected].

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