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15m Beam by Colin G4ERO

May 3rd, 2013 | Posted by Gavin, M1BXF in General

In 2012 I built a 10M beam to a YU7EF design which worked very well, it was just about manageable to mount on a SCAM mast single handed. Thoughts then turned to the possibility of building a 15M beam similarly design by Pop YU7EF. This would be a greater challenge as it would need to be light weight and be constructed in such a way that it could be safely mounted and dismounted by one person.

It was decided that it should be designed to be assembled on the mast. To boom was made in four sections. A short support boom was made with a hinge at either end to which the two centre sections were attached.

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Mounting

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This was then mounted on the mast with two “U” bolts, this pole has a couple of pulley wheels, which were homemade, and are mounted at the top of the pole, you’ll see why later.

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The mast mounting pole also has a “flat” edge ground on it at one end where it fits into the SCAM12 mast to prevent it form turning when in the socket.

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The two other boom sections are now connected to the two centre sections.

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Parachord from the ends of the boom (the ends furthest from the mast) was connected to the two ends of the pole and through the pulley wheels at the top mentioned above.

Elements

The elements were made in two sections, these were assembled.

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The elements then mounted on the boom while it’s “broken”.

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Assembly

When all five elements are fitted to the boom and the coax can be fitted to the driven element then the boom sections can be lifted into place by pulling them up with the parachord threaded through the pullies at the top of the mast. Se it all falls into place and is ingenious!

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The parachord is then clamped using the homebrew clamps mounted on the centre bracket. The boom sections then bolted to the support boom. A third “U” bolt is the used above the boom which in addition to the parachord holds the boom in place.

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