Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.2 9/18/84; site brl-tgr.ARPA
Path: utzoo!linus!philabs!cmcl2!seismo!brl-tgr!tgr!Karz.Wbst@Xerox.ARPA
From: Karz.Wbst@Xerox.ARPA
Newsgroups: net.ham-radio
Subject: Re: Roof Mounting a Beam Antenna
Message-ID: <482@brl-tgr.ARPA>
Date: Tue, 6-Aug-85 18:51:08 EDT
Article-I.D.: brl-tgr.482
Posted: Tue Aug  6 18:51:08 1985
Date-Received: Sun, 11-Aug-85 00:15:17 EDT
Sender: news@brl-tgr.ARPA
Lines: 34

Bruce,

I have a roof mount for my Hygain Explorer 14 that I'm quite pleased
with.  My antenna mast is mounted on the back side of the roof a few
feet from the peak.  I built a "frame" for the mast mount out of 3
pressure treated 2X4s about 25" long that lie across the joyces and are
bolted to the joyces with lag bolts.  The 2X4s are parallel to each
other and spaced about a foot apart.  They are not quite parallel to the
roof line and are caulked on their "uphill" sides so that they won't dam
up rain water.  The frame serves to distribute the load of the antenna
across the joyces.  I purchased 2  2' lengths of fireplace lentil at a
local brickyard.  The lentil has an "L" shaped cross section.  I drilled
holes in the lentils and mounted them on the "frame" parallel to the
fall line of the roof (that is, almost perpendicular to the 2X4s) and
with the "feet" of the "L"s pointing outward.  I spaced the lentils the
mast diameter apart.  I then drilled a hole through the mast about an
inch above the bottom and corresponding holes in the lentils.  The mast
pivots on a 1/2" bolt through one lentil, the mast, and the second
lentil.  The antenna is held up by aircraft cable guys anchored to the
roof with lag bolts.  The mast is 12' high.  I used roofing cement
around all lag bolt holes and have had no problem with leaks.  The
antenna has been up 2 years this month, and I've had no problems
whatever, but I do make a point of checking the installation twice a
year since the failure of any one lag bolt will bring the system down.
Except for the driven element, the system is a "plumbers delight" (just
one big short), so I feel that the #4 copper ground wire from the mast
gives pretty good lightning protection.  Nevertheless, I keep the
feedline disconnected from the rig and grounded when not in use as an
added precaution.

I hope my experiences is of some help to you.

Bob Karz
K2OID