Hello! Been working on getting a more “masculine” mast to hold up the 160m Inv L / Marconi T antenna / Doublet. One end is held up by an enormous Chestnut Tree, but the support at the house end has been a bit more of a challenge. So far, everything I have tried has resulted in a banana-shaped mast, either when the wind blows, or when I put a lot of tension on the halyard. There’s certainly nothing more annoying than getting some height above ground, then having a saggy top wire because the mast isn’t up to the job. So, I wanted to beef up the house end support. As usual, I had the massive G7KLJ radio budget to pool my resources from: zero! (situation normal). Here’s what I ended up with… So, with my massive budget of zero, the base of a Rohn H-50, a load of busted up clamps, old masts, a SpiderBeam telescopic pole and some steel and ally tubing, plus a lovely tilt over base that has been languishing in the shed forever, and a winch I picked up on Ebay a couple of years ago for a tenner, I set to work. Since I’d previously been using the thicker parts of a spiderbeam 12m glass fibre mast as the very top sections on the original, bendy mast, I decided this should be the first thing to go — no bendy poles, please! I’m sure Spiderbeam’s poles are great for self-supporting verticals, but they certainly can’t handle a lot of side strain for holding up one end of an Inverted L, or doublet. I would require metal all the way up, then…
Before I get a flood of emails: yes, the crosstree is SUPPOSED to be off-centre — I only have trouble guying in one direction (the direction of the longest part of the cross-tree). That’s what’s always troubled a mast in this position: all guying angles are great from its position (going out 80% of the tower’s height) except one — and sod’s law has it that the one direction I can’t guy properly are the very guys I need most — the ones pulling against the prevailing wind! So, taking a leaf from the pirate radio ships’ book, I’m trying this crosstree idea here at home. I always feel better if I can lower and raise the mast on my own, without straining my (bad) back, rather than having to rely on a helper. That’s where the winch and the hinge base came in! It really is very easy now to raise and lower the whole thing, and ZERO strength is required to do it; just a steady hand on the winch!
I have yet to see how it stands up to a full blown gale, but first impressions are good. The cross tree seems to take up the slack for the “missing” guys. If I pull as hard as I can in the “bad” direction, whereas formerly I was able to put quite a bend in the mast, now, with the cross tree, I can’t do anything no matter how hard I pull. Hey, its just an experiment, I’ll probably change it next week, but I thought you might be interested in some more ‘KLJ recycling! Here’s a shot of the other sky-hook: a very tall Chestnut Tree 50+ metres away from my home-brew mast:
And finally, a profile of the winch arrangement I made, using a steel washing-line pole, mounted parallel to the mast in its ‘up’ position, with a pulley. The Winch has huge steel rope that goes through the pulley, and is attached about 8 feet up, via a chain and bracket, to the main mast. In the end, I settled for using some of the SpiderBeam pole for the cross-tree itself (the second, third and fifth, from memory) once I was satisfied that it wasn’t too flimsy in its new role (it certainly was before!). I actually used one section (the biggest) as a coupler between the 2 inch aluminium sections near the top, as this was MUCH lighter than a 2 inch coupling sleeve.