[mythtv-users] Reconnecting an old antenna

[William Munson]

Meatwad wrote:
> William Munson wrote:
>   
>> Marc Sherman wrote:
>>     
>>> I've got an old antenna tower (probably left over from the 70s) next to
>>> my house, that I plan to reconnect as soon as my shiny new HDHomeRun
>>> arrives. The antennas (uhf/vhf) are still mounted at the top of the
>>> tower, but the cables were all cut years ago. So I'll need to connect
>>> new cables to the antenna, and run them inside to my server room in the
>>> basement.
>>>       
>
>   
>> Grounding should be done with a coax feed-through terminal block 
>> designed for the purpose. This should be done at the base of the tower 
>> if you are running the coax underground or at the outside of the house 
>> if you run the coax in the air from tower to house. You will need to 
>> drive a 3 foot long copper rod into the ground next to the block and 
>> connect the block to it with a heavy gauge wire no longer than 2 foot 
>> long. Follow the recommendations on the terminal block docs.
>>     
>
> Hmmm. Grounding rods are generally available in 5/8 and 1/2 inch 
> diameters either 8 or 10 feet long. Maybe it's just the region I'm in 
> (Chicago suburbs) but the soil/earth conductivity conditions here call 
> for a minimum of seven feet. If I can't drive it that far, I'll abandon 
> it a send another down.
>   

Yes it does have to do with the region and your local laws. You have to 
make sure that you drive it past the frost line so that it will not 
heave out of the ground during the winter and that there is enough soil 
conductivity to be effective. For lightning protection down here in 
Florida you only need 3 feet as that is where the water table is located 
and freezing is not an issue. A direct strike to your antenna will 
actually cause the ground around the grounding rod to fuse into a sort 
of glass like material as the strike heats the ground. Much better than 
balls of plasma flying around your house trying to find a way to ground 
thru whatever wiring and appliances happen to be close.

Bill