[Top] [All Lists]

[Towertalk] Grounding coaxs switch

To: <>
Subject: [Towertalk] Grounding coaxs switch
From: (Bill Hider (N3RR))
Date: Sun, 4 Aug 2002 20:13:48 -0400

Here's my advise for you.  Note, worth reading for others too:

Bill, N3RR

>Adding a bunch of ground rods and attaching #4 solid
> wire with Cadweld one-shots to my tower.

Ok so far.

> I am moving the receive coax switch from the tower to my shed - much
> to the receive ewes/pennants. My coax/control wire bundle from the house
> passes the shed on the way to the tower. The shed is 30' from the house
> the tower is 100' from the shed.
> - Should I put a ground rod(s) at the shed where the receive coax switch
> will be mounted?

Yes, and consider this:

Where ever you have such a situation (coax switch, or common node point
where coaxes converge),
you should have a ground, preferrably a single point ground (SPG).  So, I'd
add a SPG at the shed where the coaxes from the tower 70 feet away meet with
coaxes form the EWEs/Pennants and travel to the house from there.

> - Should I run something like a #6 or #8 ground wire from the tower to the
> receive coax switch? If so, should it be separated form the coax/control
> cable bundle?

It won't hurt to run #6 between the tower and the shed.  Be sure to put
ground rods
every N feet along that 70 foot run. (N= 2 times the length of the ground
Also, I'd run a #6 wire from your shed to your house, again with ground rods
every N feet, and tie
that ground wire into your SPG ground at your house. (Again, use proper
procedures here.)

> - Is it a bad idea moving the receive coax switch to a separate location
> from the tower, or doesn't it matter?

It doesn't really matter as long as all the other proper procedures are in
such as: coax grounded at the top and bottom of the tower, tower grounded at
all three legs,
SPG panel grounded at shed using proper procedures.

> As a side note, here are some things that I have happened recently.
> Started adding more ground rods as I only had 9 that were cadwelded with
> stranded copper wire. Rods have been in the ground 8 years. With an easy
> yank two of the stranded wires came off the ground rods. The ends of the
> wires were not shiny. Don't know if they corroded or if they were weakened
> by the cadweld.
> Presently replacing all of the stranded wire with #4 solid wire besides
> adding 9 more rods.

All wires should be solid not stranded.  Good thinking.

> Also, noticed that the antennas- 40, 80 and 160M, which go through a coax
> switch 4' above ground on the tower, had their resonant points go a little
> lower in freq, plus were now broader. Turned out to be the shield of the
> 1/2" hardline is open. Got it isolated to 15' which is buried under a
> bed. There are no splices in the hardline. I guess the shields of the
> hardline were acting as the return path? The other 3 hardlines have their
> shield grounded to the bottom of the tower. The hardline that went to the
> coax switch was not grounded at the bottom. Was counting on the ground
> 4' up at the coax switch.

Not proper procedure.  All coaxes must be grounded individually.  Also, do
rely on the coax connector for the ground connection of the shield.  Use a
ground kit.
Reason - the coax connector is either soldered or not, either way, the
is the weakest link when lightning strikes.  This is one of the most
overlooked grounding procedures (mistakes).

>Guess I better ground that shield at the bottom


> too. Not sure if the difference in height of the grounding kits or the
> of enough tower grounding caused this problem.

It's probably both.  Grounding of the coax should take place at the lowest
point possible on the tower.
Reason - the lower you ground the coax, the lower the Voltage potential,
thus minimizing the chance that the
potential (Voltage) during a strike will increase as the coax run proceeds.

> 73,
> Tony
> N2TK
> _______________________________________________
> Self Supporting Towers, Wireless Weather Stations, see web site:
> Call 888-333-9041 to place your order, mention you saw this ad and take an
additional 5 percent off
> any weather station price.
> _______________________________________________
> Towertalk mailing list

<Prev in Thread] Current Thread [Next in Thread>