On Dec 18, 12:30*am, Frank Wilson <frankwil...@pleasedonotspam.com>
> Any ideas for installing a new antenna mast into an old antenna hole?
> I have an old 3.5 inch ID steel tube sunk in 30 inches of concrete. I'm
> guessing this was an old satellite dish cut off flush with the surface
> (unfortunately). No threads but the steel is 1/4 thick (or so) and in
> good shape and it goes down to 30 inches in the concrete.
> I simply need an antenna mast of about 12 feet high for a new WISP 802.11
> antenna & radio setup. Winds can be high at times. Soil is rocky clay. I
> prefer NOT to have guy wires as the kids play in that area.
> The best idea is to find a way to shove a 3.5 inch OD pipe 30 inches into
> the existing pipe and then thread successively smaller pipe down to 2
> inches for the final mast. But I can't find a source for 3.5 inch OD pipe
> that has threads on at least one end so that I can put a reducer on that
> I can easily find 2 inch and 1 1/2 inch threaded galvanized water pipe
> with reducer fittings and caps - but I can't find 3.5 inch water pipe and
> associated fittings for the bottom portion of the mast.
> TWO QUESTIONS:
> Q1: If I stick with the original idea, where would I get a 3.5 inch OD
> pipe that has threads that can hold a reducer to more available widths?
> Q2: If I go with what I have right now, how would YOU shore up the pipe
> but still allow easy removal for maintenance?
> Currently it's working but physically wobbling. I remove the entire mast
> to service the antenna.
> The mast is comprised of a five foot length of 2 inch ID threaded
> galvanized water pipe sitting 30 inches deep inside the existing 3.5 inch
> ID iron pipe cut flush at the concrete. This five foot length of water
> pipe sticks roughly 2 1/2 feet out of the ground where I then threaded on
> a reducer which couples easily to the 10 foot length of 1 1/2 inch ID
> threaded water pipe forming the bulk of the mast, and which is capped at
> the top (to prevent water from filling the pipe).
> The 14 dBi planar 2.4 Ghz antenna at top is roughly pointed at the WISP
> access point; the Bullet M2 radio tells me it has an ACK/Distance of
> 55/2.6 miles respectively (I'm not sure if that's important); this radio
> sees a signal strength of -56 dBm (pretty good); with a transmit CCQ of
> 83% (just ok).
> It's working - but it's not a permanent solution.
> I am stuck at HOW to fix the antenna in the ground so that it won't
> wobble & spin (short of digging a new hole & concreting it in) yet being
> able to service the antenna (I have ladders but not a 12 foot high step
> ladder - plus the ground is sloping so it's unsafe to ladder it).
> Do you have ideas how to affix the antenna mast into the old 3.5 inch ID
> hole while still being able to remove the entire mast for antenna service?
> NOTE: In the future I'd like to add a TV antenna but that's not the
> primary goal.
> All ideas welcome.
If the dimensions you give are accurate....
You could use 3" pipe (has a 3.5" OD) obtained from McMaster Carr.
You could could a full length insert (24" to 36") and then use a
coupling w/ a threaded reducing bushing.
Buy a short piece of 3" SCH 80 pipe to make adapter donuts as
suggested by another poster.
check out http://www.alcobrametals.com/page.ph...pipe-schedules http://alcobrametals.com/page.php?page=pipeandtube
the dimensions given have tolerance on them and the various pipe sizes
& thicknesses might need some "machining" to get a proper fix.
You could wet anchor a 2" pipe (2-3/8" OD) into the existing hole
using a high strength setting compound.
Threaded pipe joints in bending situations make me nervous.