Wednesday, 19 June 2019

Fiberglass pole/mast repair

Many hams buy sets of these military surplus 4' fiberglass poles for use as portable radio masts. They are lightweight, easy to deploy and store well in the back of the car. But there's a reason that they are surplussed out from the military; they are mostly split at the bottom.

Typical split in a fiberglass pole
Over time these splits will get larger and larger. Eventually the pole will fail under stress and the mast will collapse. This will most likely happen right when you are passing that vital piece of information to the Net Control station after that tornado tore through your neighborhood and you are the only station left on the air.

My set of poles suffers from this problem. So I have made some minor repairs to mitigate the inevitable loss. I have a bracket that holds the bottom of the mast. It's about 8 inches tall and so can well support the worst damaged pole. I always use the worst damaged one at the bottom.

The worst pole gets put at the bottom where there is most support
Then using a hose clamp I secure the other poles such that they can no longer splay out. Do not tighten the clamp too tight as you'll misshape the pole. You simply want to add to the structural integrity. If the cracks are too bad you can drill a hole right at the top of the crack to prevent it from moving further up the pole. I stole this trick from the Liberty Bell 😁

Add a hose clamp to the damaged pole
Finally, assemble the poles in the usual manner. 

2 "repaired" poles seated together
In addition to the repairs I added an eye bolt to the very top pole so that I can attach an antenna wire to it.

Eye bolt installed for wire antenna. HSMM-Mesh adapter also installed.

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