Drax Felton wrote:
> My 70 ft. tower is going to be 5 feet from the corner my house with several
> runs of coax from the tower base to the radio room.
> Those runs will each be about 25 feet long to the radio.
> To start out I'm going to have three ground rods about 15 feet apart from
>
Typically the ground rods should be much closer to the base of the
tower. Say about a foot or two outside the concrete. Grounding cables
make gentle curves from the tower legs to the rods. The around 16' out
you put another ground rod on each run (IOW about twice the length of a
ground rod)
> each other in an arc around the tower and connected to each tower leg and
> then one another.
> Then one of the tower legs will be connected to the electical service ground
> which is also maybe 8 feet away,
>
>
I'd tie the grounds together through the ground cables.
> Should I install my Polyphaser lightning arrestors at the bottom of the
> tower or at the entry point where the coax enters the house?
>
>
Typically you ground the shield of each coax to the base of the tower.
The Polyphasers go on a grounded bulkhead where the cables enter the
house. This also grounds the shields at that point. I have one ground
run from the tower along the conduit to the entrance bulkhead There are
ground rods, CadWelded(TM) to the cable every 16 feet (give or take a
bit) and one right at the bulkhead. If you go to W8IJ's page you will
see he doesn't use anything other than a good grounding system.
> I was thinking about putting the arrestors on the tower base. I would then
> put ferrite beads over the coax and make a choke out of the coax where it
> enters the house on the premise that this choke point would look high
> impedance to lighting. Am I off-base in my thinking? If its an alright
> idea then how many turns of what diameter of 9913 coax makes an effective
> lightning and common mode choke at HF and at 6 and 2 meters?
>
>
I think you will find that these types of chokes are relatively
ineffective against lightning.
73 and good luck,
Roger (K8RI)
> -Drax
> KB3X
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