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Salve amici,
partendo dalla conosciuta e pluritestata M0PLK ho pensato di raddoppiare le dimensioni per poter raggiungere anche i 40m.
Ovviamente ho subito optato per le canne in fibra di vetro, l'alluminio troppo pesante e "pericoloso". Conoscevo i tubi della spiderbeam, ho scambiato un paio di email con Rick DJ0IP:
You don't have to double the size to get it to work effectively on 40m.
Mounting the poles like this is about the worst possible thing you can do with them.
If you make it just 9m per leg and feed it with openwire all the way to the shack, then place a 1:1 Guanella balun and then a tuner, it will work all bands as well. And it will be a lot stronger than having them 11m long.
You will need some pretty hefty support for the arms.
the most critical point is the point where the poles exit the support structure. That will be the point of most stress on The arms.
the supports will need to be about 1.1m long, length adjusted exactly such that the fiberglass pole exits the support in the middle of the overlap between the first and second segment. At that point, which is about 10 cm long, the pole has double thickness since there are two segments.
It is probably a good idea to cushion the poles inside of the support struts, which can be done with thin rubber strips. We have this stuff in 3mm thickness:
http://www.spiderbeam.com/product_info.php?info=p190
I cannot predict how well it will hold up.
This is how I would do it.
It uses the lower 9m of our 12m mast.
Notice where the supports end. Exactly at the point of overlap...some of the overlap must be above the support.
This is where it is strongest.
But it is going to be a monster.
Actually I would just build our 20m quad loop, run openwire all the way to the and be done with it.
Much lighter and cheaper.
Match as I said earlier.
Loops are indeed great performers.
I love them!
partendo dalla conosciuta e pluritestata M0PLK ho pensato di raddoppiare le dimensioni per poter raggiungere anche i 40m.
Ovviamente ho subito optato per le canne in fibra di vetro, l'alluminio troppo pesante e "pericoloso". Conoscevo i tubi della spiderbeam, ho scambiato un paio di email con Rick DJ0IP:
You don't have to double the size to get it to work effectively on 40m.
Mounting the poles like this is about the worst possible thing you can do with them.
If you make it just 9m per leg and feed it with openwire all the way to the shack, then place a 1:1 Guanella balun and then a tuner, it will work all bands as well. And it will be a lot stronger than having them 11m long.
You will need some pretty hefty support for the arms.
the most critical point is the point where the poles exit the support structure. That will be the point of most stress on The arms.
the supports will need to be about 1.1m long, length adjusted exactly such that the fiberglass pole exits the support in the middle of the overlap between the first and second segment. At that point, which is about 10 cm long, the pole has double thickness since there are two segments.
It is probably a good idea to cushion the poles inside of the support struts, which can be done with thin rubber strips. We have this stuff in 3mm thickness:
http://www.spiderbeam.com/product_info.php?info=p190
I cannot predict how well it will hold up.
This is how I would do it.
It uses the lower 9m of our 12m mast.
Notice where the supports end. Exactly at the point of overlap...some of the overlap must be above the support.
This is where it is strongest.
But it is going to be a monster.
Actually I would just build our 20m quad loop, run openwire all the way to the and be done with it.
Much lighter and cheaper.
Match as I said earlier.
Loops are indeed great performers.
I love them!
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