[TowerTalk] 2nd Story Station Installation

Jim Lux jimlux at earthlink.net
Sat Apr 24 13:27:42 EDT 2004


Coax entry: passing through a window is easiest, drill a hole through the
wall, all the usual techniques...

Separate the three grounding problems: Lightning, electrical safety, and RF,
and don't expect that one solution will work for all three.

Lightning protection: Direct wire from the "point of entry" to appropriate
ground. No different than, say, a DBS dish antenna.  This wire doesn't have
to (and probably shouldn't) carry RF... it's mostly to carry induced current
from nearby lightning strikes.

RF ground: Here is where it gets tricky, especially if you're talking
longwires, etc.  In an ideal world, the antenna RF ground is at the end of
the coax, all the RF stays inside the coax (or inside the rig).  In reality,
the antenna will radiate, and some voltage will wind up on the coax, etc.
BUT.. here's the basic idea... At some point (call it the "antenna
feedpoint"), you'll terminate the coax, with the center conductor going to
the antenna wire and the shield going to the ground.  Ideally, this point
should be close to "earth ground", or the wire from shield to "earth" will
be part of the antenna.
For antennas that are inherently balanced (dipoles, loops, etc.), both ends
of the wire are at the antenna, making life easy, so all you have to do is
make sure that the RF stays on the "inside" of the coax. Chokes of one sort
or another are easiest. The "coil of coax" or "string of beads" are both
viable approaches.

If you're doing the radio/tuner all sitting on the desk with a wire
stretching out through the window, you're going to have to deal with the
long ground wire problem.  A ground wire tuner can help (MFJ has them).

Mostly, it's "throw the wire out the window, string it to a tree, and see
what happens".  If it works, great. If it doesn't, then start agonizing
about how to fix it.  My officemate at work worked a good part of the world
from his college dorm room with a small wire out the window.

Jim, W6RMK

----- Original Message -----
From: "Wm. Freddy Curtis" <curtisf at dtccom.net>
To: <towertalk at contesting.com>
Sent: Saturday, April 24, 2004 8:52 AM
Subject: [TowerTalk] 2nd Story Station Installation


> Hello Tower Talkers:
> A local ham friend is planning to install a "first-time"  HF Station.
>    The problem that he has is that it will be located on the second story
> of his house.  He is in great need of information for this station.  Any
> ideas regarding coax entry into the house, RF Grounding,  and Lightning
> Protection is appreciated.  There is not alot of literature out on
> second story installations.  He plans either a 80 meter Loop Skywire or
> longwire for his antenna.  Any help will be passed on to him.  Thanks
> for the creative ideas.
>
> Freddy Curtis
> KC4GUG
>
>
>
>
>
>
> _______________________________________________
>
> See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
>
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