On 2026-04-21 3:26 PM, Gene Smar via TowerTalk wrote:
Instead of ice on it, what if the steel boom gets hot in the summer
sun and the rubber boot adheres to it? When the mast turns the boot
might rip, or at least wear a bit, allowing water in. PVC vent
pipes don't rotate and don't have this problem.
I'd consider running the mast up *through* an appropriately sized
PVC vent pipe. Make the PVC large enough that you can cover it with
a standard lead, copper or aluminum flashing and fold the top of the
flashing back down into the PVC pipe while leaving room for the mast
to rotate. The PVC vent & flashing can simply be capped with a
standard rain shield when the system is decommissioned.
Then put a "rain shield" on the mast above the vent to keep water
from running down the mast. Rain shield can be aluminum flashing,
rubber (e.g. a Fernco boot an inch or two larger than the vent)
or thin plastic sealed with bathtub caulk.
BTW, don't forget to cap the top of the mast so water doesn't run
down the inside of the mast!
73,
... Joe, W4TV
On 2026-04-21 3:26 PM, Gene Smar via TowerTalk wrote:
I also wanted to copy the list.
73 de Gene Smar AD3F
Sent from my Radio Shack TRS-80 model 100 laptop
----- Forwarded Message ----- From: "Gene Smar" <ersmar@verizon.net> To: "Mike Smith VE9AA" <ve9aa@nbnet.nb.ca> Cc: Sent: Tue, Apr 21, 2026 at 3:22 PM Subject: Re: [TowerTalk] Short Top Section for Attic Installation I'd been thinking about the same issues. Instead of ice on it, what if the steel boom gets hot in the summer sun and the rubber boot adheres to it? When the mast turns the boot might rip, or at least wear a bit, allowing water in. PVC vent pipes don't rotate and don't have this problem.
Putting the rotator outside and above the roof penetration would eliminate this problem.
The rotator would need a "lower mast support", which would block you from
feeding the coax and control wires up through the mast.
It is puzzlement.
73 de Gene Smar AD3F
Sent from my Radio Shack TRS-80 model 100 laptop
On Tue, Apr 21, 2026 at 3:00 PM, Mike Smith VE9AA via TowerTalk<towertalk@contesting.com> wrote: I find these antenna discussions fascinating.
Mechanicals aside, how would you weather -and- insect proof such an affair?
In my neck of the woods, I'd also be worried about it icing up, then turning
it and (unknowingly) ripping the weather proof barrier/boot or roofing
shingles all apart.
Secondarily, how would you replace the "rubber boot" (or whatever) down the
road?
Many years ago now, in CQ or QST magazine there was a mobile VHF contest op
who had a system like this...mast through the roof of his van(?) and the
rotor inside on the van floor (I think). Maybe someone recalls the
details.
As Artie Johnson (1960-70's TV show-"Laugh in") used to say : "Very
interesting"
GL
Mike - Keswick Ridge, NB, Canada
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