This job is not for the feint-hearted. You will need a natural tendency for engineering, be accurate and be comfortable with knots. However, there’s no reason that most small teams of keen amateur radio operators can’t build this as a project for field day use.
Let me explain how I built the one shown in the pictures, then I’ll cover the learnings with you later along with my own do’s and don’ts. Continue reading
I’m gradually swapping out any aluminium antenna poles for steel. Clearly these are very heavy, particularly with an antenna on top.
The trick is to use V bolts (like U clamps but in a V shape) and not to use saddle clamps because the pole will not slide easily past the U bolt saddle clamp.
Most radio amateur operators look at a pole* and immediately wonder how they might use it in their hobby. It becomes a weird past time and can become somewhat of a burden when passing for instance, a section of tubing in a handy-man store. I have to stop and work out if they nest together – or will they go inside some other tube I might have.
However, I have solved one riddle which is what diameter pole can I slip inside a standard steel scaffold tube?
Until recently, I had a) a 40m triangular loop in the back garden which I called a “micro-mega-loop” and b) a 60m loaded loop that allowed me to get on 80m. The two loops looked a bit horrendous not only because of the wire in the air, but because I used halyards to lift them in the air to the top of wooden stair rails. It was all very messy. They were also extremely close together along the back of the garden which meant some of my RF was absorbed by the other loop. See here: http://www.m0mcx.co.uk/sg-230-feeding-60m-skyloop-deltaloop/
I like loops for two reasons, a) for my small garden plot, I can achieve in half the size, what other do with a full size dipole and b) a resonant loop will also resonate on every harmonic, that means tuning a 40m loop at 7.1 Mhz means I also get 14.2, 12.3 and 28.4 Mhz.
(This article contains an animation)
(Note, this product is at the “enquiry” level, it is not a stock part from Barenco)
If you haven’t heard of them, then you should. Barenco make the finest brackets and supply other amazing stuff for the amateur radio hobby. Here’s Brian’s link:
I dropped an email last month to Brian asking him for some custom work but explaining something in writing that will produce a piece of engineering can cause spurious results. I therefore used my new (free) toy, a 3D modelling program called SketchUp to show Brian what I was after.
Essentially, it’s an off-set, side-mount rotator bracket that is also tilt-over. Since the bottom of this mast will only be about 2.5 above the ground, I’ll easily be able to secure the rotator bearing, undo the bolts at the top and carefully lower the mast down with a 6:1 pulley set I have.
Here’s the walk-through as an animation:
A 10k generator and a lighting tower; the ultimate toy for a radio amateur. You get a generator, a hydraulic 10m tower and big, big lights – all in one package. It’s heavy but with a braked trailer and the right vehicle, it’s breeze.
Picture shows tower at about half-height and Barry has kindly offered to make a rotator housing for the very top of the unit which we’ll sort out this winter.
It’s easy to climb on top to make adjustments (mandatory at a field day with rotator housing fitting etc) and only 20 seconds to “wind” the tower up. Fair dinkum, it’s not a 100 foot tower but horses for courses, a great little easy-to-use package.
We should be operational for next Spring (2008) where we can enjoy some lazy days out in the Cotswold Hills on VHF – as well as HF Field Day (which was the initial reason for getting it!).