Getting ready for two BF runs to the new tower. It will be in PVC. Since
it's out of site I use the white PVC. Costs less than the gray. The main
worry about moisture is temp. variation causing the PVC to 'sweat'
inside & eventually to get water in the lowest spot of the run. My run
to my HyTower is apx. 120' in PVC. Downhill all the way but there's a
dip about 20' from the HT. I drilled several 1/8'' holes on the bottom
of the PVC at it's lowest point. The PVC is several inches below the
surface all the run. At that low point I dug a hole the size of a 1 Lb.
coffee can & filled it with pea gravel. Any moisture will run to the low
point & exit thru the holes into the gravel. I prefer to seal the end
where the coax exits at the tower base. We have lots of nasty insects in
W Tn & don't want them finding a home. Here if you store EMT, PVC or
aluminium elements they need to be taped on the ends to prevent insects
from entering. We have 'dirt daubers' & they can stuff mud 6'' into the
ends. A real pain flushing them out. It hardens like cement. Other bugs
like the ends of my spare Rohn 25 sections as home. I've flushed them &
they are taped too.
I learned the value of 'drip loops' in the coax lines coming off
towers. At the old QTH I forgot to add one & one day I discovered a
spoon full of water on the OP desk behind the radio. Whether it ran
inside or outside of the coax I don't know but it managed to find it's
way inside the house.
K9IL
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