PPM: A Plastic Antenna Mast

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From: William K Hibbert (wb2vuo@juno.com)
Date: Sat Jul 06 1996 - 15:32:00 EDT


Note: This was originally posted on packet in 1993, and was printed in
the BARK (Brockport ARKlub) newsletter, and the Rochester VHF Group
journal...
I am posting this due to the number of queries/requests for PVC/Mast
projects that I have seen in the last couple of weeks...Keith, WB2VUO
(in the Depths of the Great Bergen Swamp!!)

                    PPM: A Light-Duty PVC Pipe Mast

Over the 25+ years that I have been a ham. I have seen a few antenna
supports, [ and have built a few, myself ]. One of my brothers, John,
KB2SIL, has come up with a light-duty, inexpensive and easily built PVC
Pipe Mast, PPM for short.

On John's first attempt on the PPM, he acquired (3) 10-foot lengths of
1 1/2" NPS PVC pipe. The actual outside diameter of this is 1.99",
with a nominal ID of 1 1/2". He put the three lengths together with
straight couplings and PVC cement. However, when he tried to raise
the mast into the air, the cemented joints failed catastrophically,
resulting in PVC hash and scraps all over the back yard. Something
else needed to be done to improve the mast mechanically.

In PPM, Part II, John used a piece of the PVC for sleeves at each
joint, cutting a pair of 2-foot lengths from some of the scrap, and
splitting them lengthwise with a hacksaw. These split sleeves were
held in place with four stainless steel hose clamps, two above, and
two below the joint. This proved to be entirely adequate, and he set
the mast up at the end of the house. Using a mast bracket, re-drilled
for a larger U-bolt, and a set of light Nylon guys at he 20-foot
level, he erected an 80 - 10 meter G5RV. This put the feedpoint up at
29-feet, just right for the 300-ohm twinlead, and the plastic mast
doesn't affect the balance on the line!

As a bonus, and seeing that he didn't have his ticket back then, I
checked out the antler for him. It plays as expected on not only 80 -
10 Meters, but also on 6 Meters. We were able to raise a 6-Meter
repeater about 40 miles south of his QTH with around 3 watts. The SWR
was normal for the HF ranges, being best on the 20 meter band, and was
within the ATU's adjustment range on all the other HF bands.

John is in the Syracuse area, with a fairly well-sheltered back yard.
Out here on the windswept flats [swamps] of Bergen, I wouldn't expect
the PPM to survive, unless I guyed it 6-ways to Sunday, but I am
eyeing the leeward end of my barn as a possibility. I would think
that the PPM would work well in almost any urban/suburban lot, and
being PVC, one wouldn't have to worry about corrosion and/or water
damage.

If you try out John's PPM, drop me a line here on packet...
73, Keith, KE2DI [Now WB2VUO (again!)]

BTW:You can save bandwidth, and contact me, or John directly. My E-Mail
ADR is - wb2vuo@juno.com
John's is - johnh@mailbox.lpl.org
          or - john_hibbert@lpl.org


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