[mythtv-users] Reconnecting an old antenna

[William Munson]

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.
>
> A few questions:
>
> - What cable do I use? RG-6?
>   
RG-6 is good as long as you have a preamp installed at the antenna or 
very close to it. Some can be mounted to the tower itself.
> - Is there a max run-length for that?
>   
With the preamp you should not have an issue with cable length for any 
reasonable home installation as the gain of the preamp will overcome any 
losses in the cable. Do not use a preamp mounted inside your home as 
once the signal is lost in the coax it cannot be recovered and all you 
will be doing is amplifying noise.
> - What about grounding? Is it safe to run that cable straight into the
> house, or does it need to be connected to ground somewhere? Or is the
> antenna tower itself enough grounding to be safe from lightning?
>   
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.
> - Is there anything I need to pay attention to reusing a very old
> antenna? The tech hasn't really changed all that much in decades, right?
>   
Biggest issues you will run into are corroded hardware which will not 
move without breaking the age brittled element mounts and the bigger and 
VERY SERIOUS issue is that the 30 year old tower is quite likely to 
collapse when you try to climb it. Be sure to use a climbing belt and 
pick a calm day to minimize wind loading. I personally would not trust 
my safety to 30 year old guy wires and steel that has been rusting away 
for 30 years. No professional tower climber would attempt to use that 
old of a tower unless it has had meticulous maintenance over the years 
and has had things replaced as they wear.

I have been a ham radio operator for 30 years and have owned and climbed 
many towers over the years. I do know what I am talking about and have 
lost a friend to a old tower collapse. Put safety first over money you 
might save.

Bill

> Thanks,
> - Marc
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