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Re: Coax Selection



Roy -

Well that is a good point.  I would at least run a ground wire from the
antenna
masts to an outside ground wire.  I would also probably use
some type of Transi-trap protector (Alpha Delta or others) .

Greg
w9gb


----- Original Message -----
From: <rdwelch@swbell.net>
To: "Tipton, David M." <tiptondm@opensysgroup.com>
Cc: <amsat-bb@amsat.org>
Sent: Thursday, November 08, 2001 3:21 PM
Subject: Re: [amsat-bb] Coax Selection


> David,
>
> I did this with my satellite coax runs.  I had two 1/2 inch hardline runs
> along with my rotator cables.  I used a regular power weather head which
> has a removable top for access along with a plastic portal with knockouts
> for the coax to pass through.  It is easily caulked around the openings to
> keep varmits out.  I ran the coax through the attic and down to the
> basement via a return air duct between the studs in the wall.  I used this
> route because it contained no fire break halfway down the wall.  I exited
> in the basement and turned back up again into the wall behind my radio
> desk.  The half inch coax was entirely inside with short flexible runs
> beginning just inside the weather head for a fifteen foot run to the
> antennas and again in the basement for the short runs to the rigs.  This
> worked beautifully for many years and the 1/2" coax is as good as new.
>
> However I was concerned about two things.  I suspected that if I ever took
> a direct lightning stroke on the antennas, the stuff was going to follow
> that solid aluminum jacket into the attic, etc. where it could easily
start
> multiple fires.  In addition, since I am getting a bit older now and can't
> climb around in the attic as I used to be able to do, I thought it might
be
> a good time to get the coax run outside again.  This was influenced by the
> eventual roofing job I will need when I can also replace the plywood
> section where the hole is.  So I bought a couple of runs of Times LMR-600
> coax and added a few feet by running it on top of the roof to the edge and
> down the side of the chimney through metal brackets fastened into the
brick
> mortar.  I entered the basement wall through a 3 inch pipe with a 45
degree
> downturn on the outside and turned up to the shack through the same holes
> as before.  The run is 70 feet.  The total loss at 435 is 1.2db.  I did
> move the preamp from the shack end to the antenna end of the coax and the
> signal was improved over the old setup.  The antenna grounding lead is a
> stranded piece of #4 cable running in parallel with the coax and rotator
> cables to a ground rod just beneath the cable entrance through the
basement
> wall.  The 3 " entrance pipe was stuffed full of fiber glass insulation
and
> the outside end filled with silicone caulk.
>
> Your run sounds like it is so short that I doubt you will see any
> difference regardless of the path you choose.  I'd take the easiest one to
> maintain, especially at my age :-)
>
> "David M. Tipton, Ph.D." wrote:
> >
> > I am going to go pick up some coax this weekend (Or maybe even tomorrow
at
> > lunch) for my sattelite antennas.  The plan is to cut a whole in the
roof,
> > mount a "Vent Pipe" with an angled end (Looks like an upside down J) and
run
> > the coax through this, and run the coax the 5 feet across my attic and
down
> > through the wall into the shack.  (I have a 1 story home.)  The total
> > distance from the antenna mount to my rig, is about 30 feet.  I figure
on
> > adding an additional 20 feet to compensate for errors in calculations
and
> > for rotation.
> >
> > This means that my total run will be around 50 feet.
> >
> > I want to know, on a run this short, what are my best cost/performance
> > options?  Will 9913 work well?  Or Just Well Enough?  Would I be wasting
my
> > money going to something like LMR400?  Would I gain anything worth
noting by
> > going to LMR 600?
> >
> > Am I overlooking any other obvious choices?
> >
> > These coax runs are to feed the UHF and VHF Sattelite antennas btw.
> >
> > Dave
> >
> > ----
> > Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
> > To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
>
> --
> 73, Roy
>
> Internet: w0sl@amsat.org
> Home Page: http://home.swbell.net/rdwelch
> ----
> Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
>

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