MAST HOLE FOAM FILLERS

[KENT TRIMBLE]

There are a number of polyurethane-type foam post-hole fillers on the
market (Sika, Rainbow, Secure Set, Poly-Set, Postloc,etc.).  I would
appreciate a brief discussion (10 replies maximum) from knowledgeable
construction people as to what might be best for the following application.

I'm wanting to anchor a 50-foot Max-Gain Systems MK-8-HD fiberglass
push-up mast weighing 24 pounds which will support a 5-inch plastic
center-insulator bearing 16-gauge open-wire feed-line and ~130 feet of
16-gauge radiator wire.

The foam will surround a 3-inch o.d. Schedule-40 PVC pipe in a 3-foot
deep hole.

I'm prepared to further stabilize the mast above ground with T-posts.

Product-knowledgeable replies only, please, especially from utility
company personnel who anchor utility poles with this stuff.

73,

Kent Trimble, K9ZTV
Jefferson City, Missouri




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[Bill-3]

A PVC mast 3' into the ground will easily break off - use 2" galvanized
pipe and allow several feet above the grass level. This will allow you
to connect the 50' mast to same. Best to make a swivel mount several
feet off the grass level to allow for putting it up and down. You must
guy this tower every 10 feet or it will do the dance in the wind. For a
light weight installation that is well guyed you can use post setting
mix. You should use a tube and make a mushroom at the bottom to keep
frost heaving at bay.

Guying is very important - you will gain most of your wind resistance
strength from it. It will not survive even modest winds without guying.

I do something similar with a 25' piece of 2" aluminum pipe fastened at
the grass level to an 8' T-post driven in 4'. The tower is guyed at 12'
and the top. Guys go to T-posts and are tied off above 4' to provide for
easy mowing. T-posts must be the heavy cast types - rolled are just junk
and will easily fold under any load.

My NVIS wire antennas (75 and 40 meters) have survived in excess of 70
MPH winds with no problems at all. My system has been up for about 10
years without any failures.

Just remember, 50' is about four times more of a problem than my 25'.
Also, aluminum pipe, although more expensive, will be much more solid
than any plastic tube.

Bill W2BLC


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[Lee Ormiston]

Kent,

Suggest you read and perform the calculations in Calculating the Required
Mast Strength section of *ARRL Antenna Book.  *You will also want to search
NWS.gov web site for Maximum Recorded Wind Gust speed at weather reporting
stations nearest you.

NORRL Lee

On Mon, Apr 29, 2019 at 5:47 PM Bill <[hidden email]> wrote:

> A PVC mast 3' into the ground will easily break off - use 2" galvanized
> pipe and allow several feet above the grass level. This will allow you
> to connect the 50' mast to same. Best to make a swivel mount several
> feet off the grass level to allow for putting it up and down. You must
> guy this tower every 10 feet or it will do the dance in the wind. For a
> light weight installation that is well guyed you can use post setting
> mix. You should use a tube and make a mushroom at the bottom to keep
> frost heaving at bay.
>
> Guying is very important - you will gain most of your wind resistance
> strength from it. It will not survive even modest winds without guying.
>
> I do something similar with a 25' piece of 2" aluminum pipe fastened at
> the grass level to an 8' T-post driven in 4'. The tower is guyed at 12'
> and the top. Guys go to T-posts and are tied off above 4' to provide for
> easy mowing. T-posts must be the heavy cast types - rolled are just junk
> and will easily fold under any load.
>
> My NVIS wire antennas (75 and 40 meters) have survived in excess of 70
> MPH winds with no problems at all. My system has been up for about 10
> years without any failures.
>
> Just remember, 50' is about four times more of a problem than my 25'.
> Also, aluminum pipe, although more expensive, will be much more solid
> than any plastic tube.
>
> Bill W2BLC
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

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