I don't have that luxury either...my shack is on one end of the house
while the power and telco come in the other. Hence the perimeter ground
to tie them together at the power/telco entrance.
The telco is protected at that point also, which I guess you can say
is an SPG for "that" equipment. When referencing an SPG for the shack
the articles are referring to the HAM equipment's SPG.
CATV does come in the shack area and since my Internet service comes over
the CATV line and is connected to my cable modem and computers,
a whole new problem is created. The Ham computer is tied to the other
main computers via a hub and a router on the other side of my office.
This requires a strategy to prevent ground loops between all the radios
and computers, which are on a different circuit, but linked with Cat5.
Any one circuit left out of the overall plan can compromise the entire
system.
I've already been hit once though the power lines and lost my computers,
vcr's, tv's, security system and my wife's electronic sewing machine.
The insurance guy couldn't believe what that machine was worth.
My Ham gear was all connected and off but I didn't lose one piece of that
equipment. Go figure! It was on a different circuit and all grounded.
At the time I didn't have the ham computers connected to the other computers
via cat5. Otherwise I may have lost some of my ham gear.
A whole house protector is next on my list.
Joe -
-----Original Message-----
From: Guy Olinger, K2AV [mailto:k2av@contesting.com]
Sent: Thursday, September 19, 2002 11:51 PM
To: kc2tn@comcast.net; 'Bill Hider (N3RR)'; 'Jon Ogden'; 'Tower Talk
(mail list)'
Subject: Re: [Towertalk] Box forSPG and Lightning protectors
Part of the confusion here is that a made-to-order commercial radio
room is usually going to be a single room inside a shelter, built on a
concrete slab, and the problem is protecting everyone's stuff inside
the shelter.
The main thrust of the answer is tying everything going out/coming in
to a single point ground panel.
Since it is a single room building, the SPGP is also how everything
gets to the outside. EVERYTHING. Power, telephone, radio leads,
EVERYTHING. It's got all the suppression gear mounted to it, a very
short thick ground lead to the external ground system, which includes
the power company ground.
Now what happens when you take this very successful strategy and try
to export it to a residential situation?
Well, if your radio room is next to where the power and telephone come
in, and it is feasible and acceptable to route the outside ham wiring
to the same place, then you have the maximum system available to your
residence. Just do it.
What if you don't. Then what do you do?
You extend the system so that no aspect of the commercial radio room
SPGP is lost in your house. Consider my house as a kind of worst case
for purposes of demonstrating the principle.
Unfortunately, when you do, you have to duplicate some provisions to
accomplish the same thing.
In my case I have power and tel to the front of the house. I have ham
radio and two different remote power feeds to the back of the house. I
have a shack over the garage at a distance from either of the two.
Going around the house IS OUT OF THE QUESTION. (No, don't ask...)
This means to fully protect my situation, I have to have THREE SPGP's.
One at the ground in the front for power and tel, one at the ground in
the back for power feeds and ham radio, and one at the shack, for
EVERYTHING that comes into the computer and radio rooms.
The SPGP's are connected by heavy conductors, in what is essentially a
thick copper triangle.
All elements going through a given SPGP are suppressored at that
point.
This means that circuits going through two SPGP's go through two
suppression points. Power goes through suppression on all three
points.
Consider the Polyphaser writings what you do when you are lucky enough
to have all three of my suppression points at the same place.
Once you get the idea, it's pretty simple.
73, Guy.
|