[kwlug-disc] Home made indoor TV Antenna

John Johnson jvj at golden.net
Thu May 1 16:14:07 EDT 2014


On 2014-05-01 15:23, Paul Gallaway wrote:
> Also, of utmost importance, don't overlook grounding your antenna!
>    
Agree.
And research lightning protection devices on the cabling from the mast.*

Many years ago I set up a PC at house / SOHO office in Breslau.
The fellow there ran a business with a few trucks which had CB radios.
And CB base station, with a mast mounted, whip antenna at the SOHO office.

The PC was set up with a grounded, surge protected, power bar on one 
side of the room.
The CB base station was on the other side of the room on another outlet 
along with a stereo receiver.

There was a storm.
And a lightning strike.**

The mast mounted whip antenna disappeared. Bit and pieces of the 
fibreglass were found all over the neighbourhood.
The CB base station and the stereo receiver were bricked.

The PC lived.
But I would suspect that the surge protected, power bar was, after the 
lightning strike, a normal, non-protected, power bar.
(n.b. The surge protection circuit components are sacrificial.)

* I have not looked for these in recent years, but lightning protection 
components on antenna cabling are mounted outdoors before the cabling 
enters the building. These components provide a bypass, or path to 
ground, for lightning induced surge voltages so that these surge 
voltages are reduced at the antenna terminals of the equipment inside 
the building.

** Almost nothing will protect against a direct lightning strike as the 
energy to be dissipated is just too high. Typical protection circuits 
are intended to protect against lightning induced voltages, i.e. those 
voltages induced in conductors near a lightning strike and induced by 
the rapidly changing magnetic field around the strike.

/lecture

JohnJ
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