Advice sought for installing a 2" WISP antenna in an existing 3.5"cut-off mast hole

On Sun, 18 Dec 2011 23:00:10 -0800, Jeff Liebermann wrote:
> Why do you need to lower the pipe?
> A 12ft step ladder should be sufficient.

I guess I could buy a 12-foot step ladder - but the footing is
problematic as it's on a slope.

I'm hoping to design in the ability to be able to lower the pipe for
maintenance.

> Get a 12ft ladder. Without guys, the pipe will not support your
> weight so forget about slithering up the pipe using foot pegs or an
> ascender.

I was worried about that. I'm over 200 pounds.

> You'll have a problem trying to get the 1.625" U bolts that come with
> the typical TV antenna to fit the pipe.

I didn't realize this. I guess I'd remove the 1 1/2" water pipe end cap
at the top of the pole and then thread on a reducer to reduce it down to
1 inch for a couple of feet at the top.

Would the typical TV antenna fit onto a 1 inch ID water pipe?

On Sun, 18 Dec 2011 23:00:10 -0800, Jeff Liebermann wrote:
> Why do you need to lower the pipe?
> A 12ft step ladder should be sufficient.

I guess I could buy a 12-foot step ladder - but the footing is
problematic as it's on a slope.

I'm hoping to design in the ability to be able to lower the pipe for
maintenance.

> Get a 12ft ladder. Without guys, the pipe will not support your
> weight so forget about slithering up the pipe using foot pegs or an
> ascender.

I was worried about that. I'm over 200 pounds.

> You'll have a problem trying to get the 1.625" U bolts that come with
> the typical TV antenna to fit the pipe.

I didn't realize this. I guess I'd remove the 1 1/2" water pipe end cap
at the top of the pole and then thread on a reducer to reduce it down to
1 inch for a couple of feet at the top.

Would the typical TV antenna fit onto a 1 inch ID water pipe?

On Sun, 18 Dec 2011 23:00:10 -0800, Jeff Liebermann wrote:
> Why do you need to lower the pipe?
> A 12ft step ladder should be sufficient.

I guess I could buy a 12-foot step ladder - but the footing is
problematic as it's on a slope.

I'm hoping to design in the ability to be able to lower the pipe for
maintenance.

> Get a 12ft ladder. Without guys, the pipe will not support your
> weight so forget about slithering up the pipe using foot pegs or an
> ascender.

I was worried about that. I'm over 200 pounds.

> You'll have a problem trying to get the 1.625" U bolts that come with
> the typical TV antenna to fit the pipe.

I didn't realize this. I guess I'd remove the 1 1/2" water pipe end cap
at the top of the pole and then thread on a reducer to reduce it down to
1 inch for a couple of feet at the top.

Would the typical TV antenna fit onto a 1 inch ID water pipe?

Jeff Liebermann wrote:

> On Sun, 18 Dec 2011 08:30:46 +0000 (UTC), Frank Wilson
> <(E-Mail Removed)> wrote:
>
> > 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.
>
> That would be about the size used for a big C-band 8ft dish. DBS
> dishes use smaller pipes, usually 2".
> <http://www.dbsinstall.com/diy/reference/PipeAndTubeWallThicknessChart.asp>
>
> > 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.
>
> How's your stick arc welding? Jack hammer enough of the concrete from
> around the pipe to expose enough of the original 3.5" ID steel pipe to
> make an effective weld. Find an internal sleeve that's approximately
> the correct size. My guess is 3" steel pipe will have roughly a 3.5"
> OD can will make a good sleeve. You might have to do some grinding to
> the OD in order to get it to fit. Pound it into the original 3" pipe
> in the ground. Make some effort to get the pipe to be exactly
> vertical. It makes antenna aiming MUCH easier. Tack weld in place.
>
> When you're done welding the stub/nipple, you'll probably need to mix
> a little concrete and fill in the area around the welt to prevent
> water accumulation. I suggest removing as much slag as possible and
> painting with a rust resistant paint, before applying the concrete.
>
> At this point, you have several choices. If you use a threaded 3"
> steel pipe, you can attach any of an assortment of pipe fittings to
> extend the pipe to the desired altitude. However, I wouldn't do that.
> 12ft is a LONG way to go with a single steel pipe. Even with pipe
> fitting or pipe union, it's going to wobble. You're also looking at
> 7.3 lbs per foot for 3" pipe or 88 lbs of pipe.
> <http://www.engineeringtoolbox.com/steel-pipes-weights-d_774.html>
> If you don't like guy wires, you'll need to do a good stick arc
> welding job.
>
> You can go to a smaller diameter pipe, but if your 2.4GHz antenna has
> a narrow beamwidth, you're going to have alignment stability problems,
> especially when the wind is blowing. For example, the common 24dBi
> parabolic dish antenna has about a 6 degree -3dB beamwidth, which has
> to be aimed within about a 3 degree range to be usable. That's not
> easy on top of a 12 ft pole unless it's VERY stable.
>
> > 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?
>
> Any plumbing vendor. Ask for 3" ID 40 steel pipe. I would NOT try to
> pound a 12ft pipe length into the 3.5" pipe that's in the ground
> (unless you have a 15ft ladder and find it entertaining to use a
> sledge hammer on top of the ladder). Use a welded stub/nipple pipe as
> previously described.
>
> > Q2: If I go with what I have right now, how would YOU shore up the pipe
> > but still allow easy removal for maintenance?
>
> Nipple sleeve welded in order to extend the original pipe above ground
> level. Use a pipe coupler if you want to make it strong an permanent.
> Use a pipe union to make it removable but not so strong. Unions are
> not made for this type of service. I couldn't find if it will handle
> the bending load. That should be researched before building.
>
> Why do you need to lower the pipe? A 12ft step ladder should be
> sufficient.
>
> > 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).
>
> Ubiquiti products are good. A 14dBi panel antenna means it's probably
> a sector antenna (kinda rectangular looking), which will have about a
> 15 degree vertical beamwidth and about a 60 degree horizontal
> beamwidth. That's not very critical or difficult to aim. If your
> pipe is really vertical, and you have line of sight, you could
> probably preset the antenna and not worry about tweaking it once
> erected.
>
> > 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).
>
> As previously mentioned, chip away some of the concrete. Pound in a
> 3" pipe stub/nipple. Arc weld. Add mast.
>
> > 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?
>
> Yep. Get a 12ft ladder. Without guys, the pipe will not support your
> weight so forget about slithering up the pipe using foot pegs or an
> ascender. If this bothers you, I suggest you forget about the pipe,
> and switch to a 10 ft section of Rohn 25 tower. Weld the base plate
> to what's left of the 3.5" pipe in the ground. You will also need to
> drill into the concrete to secure the base plate mounting bolts.
>
> Hmmm... with small brats climbing everything in sight, maybe not...
>
> > NOTE: In the future I'd like to add a TV antenna but that's not the
> > primary goal.
>
> You'll have a problem trying to get the 1.625" U bolts that come with
> the typical TV antenna to fit the pipe.
>
> Good luck. Try not to kill yourself doing this.

If you are going to weld, and rather than use guy ropes, you could brace the pole effectively by using standoff tabs and full length reinforcing rod in four vertical positions.

On Mon, 19 Dec 2011 21:42:19 +0000 (UTC), Frank Wilson
<(E-Mail Removed)> wrote:

>On Sun, 18 Dec 2011 23:00:10 -0800, Jeff Liebermann wrote:
>> Why do you need to lower the pipe?
>> A 12ft step ladder should be sufficient.
>
>I guess I could buy a 12-foot step ladder - but the footing is
>problematic as it's on a slope.

Look for an "orchard ladder". It has a pipe stabilizer on the other
side to keep from bending the mast with your weight.
<https://www.google.com/search?tbm=isch&q=orchard+ladder>

>I'm hoping to design in the ability to be able to lower the pipe for
>maintenance.

Tilt over masts and towers are available commercially from the various
tower suppliers. You will not like the price. You can also make your
own. Look at the photos for ideas:
<https://www.google.com/search?tbm=isch&q=tilt+over+mast>
If you change your mind about the guy wires, it can be done quite
easily with a base mounted hinge point. You also won't need a heavy
weight mast as a simple 10+5ft, 1 5/8" dia, will suffice if you keep
the weight down. For example, no rotator. If wind loading is a
problem, go to an antenna with a smaller wind load, such as a 19dbi or
24dBi barbeque grill parabolic dish. As for the kids, you might try
installing springs on the guys. When they crash into the guy wires,
the damage will be minimal.

>I was worried about that. I'm over 200 pounds.

Ok, get a heavy duty ladder and work with a mattress under the ladder.

>> You'll have a problem trying to get the 1.625" U bolts that come with
>> the typical TV antenna to fit the pipe.
>
>I didn't realize this. I guess I'd remove the 1 1/2" water pipe end cap
>at the top of the pole and then thread on a reducer to reduce it down to
>1 inch for a couple of feet at the top.

That will work, but ever fitting will weaken the mast and possibly
make it wobble. For mounting the TV antenna, you can build some
manner of adapter or creative mounting contrivance. I have a mess of
these for the occasion (except mine are 1/4" aluminum and much
larger). Make your own to fit.
<http://www.ebay.com/itm/250838545235>

>Would the typical TV antenna fit onto a 1 inch ID water pipe?

That you could have figured out yourself.
<http://en.wikipedia.org/wiki/Nominal_Pipe_Size>
1.315 OD which is less than 1.625 for the TV mast. Yes, it will fit.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com (E-Mail Removed)
# http://www.LearnByDestroying.com AE6KS

On 12/18/2011 11:19 PM, Jeff Liebermann wrote:
> On Sun, 18 Dec 2011 19:09:08 -0800, miso<(E-Mail Removed)> wrote:
>
>> Note whatever you use as "cement", it has to set in the winter. Well
>> unless the OP is from down under.
>
> Two part catalytic mixes will set at any temperature.
>
>> I run into installations in the boonies where it looks like stakes were
>> epoxied into crevices of rock. Any idea what kind of compounds are used
>> to do this?
>
> "Anchor bolt grout", usually a two part epoxy. You'll find it at any
> hardware store that sells to builders:
> <http://www.henkelna.com/industrial/loctite-fixmaster-anchor-bolt-grouts-7052.htm>
> <http://www.drillspot.com/products/559445/loctite_1108757_non-sag__no_odor__solvent-free__high_performance_2_part_anchor_bolt_grout_hp >
> <http://www.rohs.loctite.com/us/content_data/53624_lt4731_loctite_grouting_solutions_sell_sheet .pdf>
> Look for Loctite 1108757. You won't like the price.
>
>> This is sort of the case where you don't know how to ask the
>> right question in google. In fact one spot had threaded pipe in the
>> rock, and I suspect they found a hole and just filled it to set the pipe
>> rather than dig into rock.
>
> I carry several star drills in my install kit. I hate pounding holes
> by hand into existing concrete pads, but it works. I've never tried
> it on rocks.
>
>
>
>
I think the gray stuff is what they used. Thanks.

The place where I saw this pipe and anchors was listed to have a seismic
sensor in the general area. I suspect the antenna was mounted with the
pipe in the ground (actually rocky hillside) and guy wire eyelets. You
wouldn't even notice this spot if you weren't hiking up the hill. My
guess is it would have been too much work to take it out.