Bent Gainmaster

[NightProwler]

So after yet another storm my 11 year old GM has a bend in it half way up. Im going to take it down on the weekend and see whats happened. Could this be due to a crack or can fibreglass antennas just bend? Bloody British weather

[Transwarp]

Yep, the recent storms one after the other we've just had will have no doubt damaged or even wrecked a fair few base antenna installations.

As for your FG Siro, if it's not suffered tearing or crack damage then at a guess if enough constant force is supplied for a long enough period to keep it arched in one direction it could end up with a bend, and as fibreglass is a non memory material it won't return to its original position when that force is eventually removed. A bit like plastic pipe that if you heat it up and flex and hold it like that until it cools it will stay in the shape you held it at.

[NightProwler]

Well its coming down on the weekend so I can see whats happened. Its not a bad bend but its got me worried. I will not let my GM die as I have worked the world on it. Hopefully the weather is ok on the weekend

[Buick Mackane]

I took my end fed down before the storm hit, Just as well as it would have been took out by the airborne trampoline that landed in my neighbours garden

[Transwarp]

Well its coming down on the weekend so I can see whats happened. Its not a bad bend but its got me worried. I will not let my GM die as I have worked the world on it. Hopefully the weather is ok on the weekend

If it's a case of just some sections that have been strained into a slight bend then it may be possible to make them straight again. To do that will take some time and patience though. You'd need to first roll each section of the antenna on something perfectly flat, like a sheet of glass example, then you'll be able to see any bend on each section and mark its position. Then you'd have to knock up a simple jig, two pieces of straight and true thick angle iron screwed onto a length of flat surface timber and then placed on a known flat surface like a smooth concrete floor, then place each section needing attention into the jig (the sections need to be a tight fit between the two lengths of angle iron with the bend facing one side of the angle iron) and carefully heat up the section with a heat gun until it all feels very warm then leave it to cool completely.

What trying to achieve is to introduce some slight elasticity in the fibreglass with the heat, the jig is providing the holding force to keep it in a straight position until it cools down when hopefully its removed it will stay in that position.

Without getting into chemistry it depends if the sections were made with a thermoplastic type resin or matrix type, thermoplastic will respond to heat manipulation better than matrix type will, just go carefully, heating up slowly and not too much otherwise you'll weaken and maybe deform the structure of the material, if it starts to discolour you've applied way too much heat.

Hope you can salvage your antenna and good luck.

[NightProwler]

Cheers for the advice If there is a split or crack then I have loads of different size plastic pipes in work that I can use to repair it by putting a sleeve over the damaged part, I was watching some youtube videos last night about it. Well if it's nice this weekend ( ) I will get it down and take a look. I will keep you updated.

Hey Jason I thought you had an old stair bannister wrapped in tin foil nailed to your garden fence

[Buick Mackane]

Hey Jason I thought you had an old stair bannister wrapped in tin foil nailed to your garden fence

I do Richie but its not wrapped in tin foil My EFHW runs from the drain pipe just above my bathroom window out to the pole (Bannister) Which is approx 16ft high, The recent storm brought part of the fence down but not the part the pole is attached too,

[NightProwler]

Well I took it down and yes it has a crack at the top of the second section. I repaired it and now have guy wires on it. How long it will last I dont know so I might end up replacing it at some point. Cheers for the advice dudes

[Transwarp]

Yes I've seen a couple of YT vids about guying them. Do they come in two flavours, a 1/2 and a 5/8 wave? Think the vids were for a 5/8 one.

Judging by the design of them l'd have thought it possible to replace all the sections completely with more robust fibre glass rods and lessen the amount of separate sections required and also improve upon joining each section together rather then having them slits at the top of each section.

I've not seen a GM in the flesh myself, only fibreglass h'base antenna l ever owned was a Shakespeare big stick and it lasted years, in fact when l moved home back in the day and took it down l sold it to a friend who was after it and he had for quite a few years as well.

[NightProwler]

Mine is the 5/8 version, Had it about 10 or 11 years now. It seems a hell of a lot better now it has guy wires on it, Just wish I put them on ages ago. A mate of mine has one and it snapped at the bottom in the last storm we had. The best fibreglass antenna I owned was my imax 2000. It out performed my GM but when I moved house I could not get it apart, Tried everything. It wouldent fit in the van we used for moving so I had no choice but to cut it up with a saw and throw it out

[Transwarp]

Sad end to the imax after years of faithful service then eh? Never mind, sometimes when there's no other options you have to do what you have to do.

Hope your GM stands up to the elements better now with the guy lines

[NightProwler]

I was crying like a baby when I was cutting it up. I want another one but im not paying almost £200 for a pile of fibreglass.

[k40]

I put up one of those Shakespeare ABS1600 in about 2000, still there faded from what it was, but still holding up after 24 years.
Not as good as an Imax or A99 on paper but a lot tougher so worth it to me.
Even though the swr is highish on 10M I still got Brazil fairly easily.
It whips about in the wind, I've not taken it down and checked it in a long time.