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Post by Priapulus on May 25, 2016 11:23:38 GMT -5
I recently installed a TV antenna on my tower, with an amplifier on the mast and the usual 75 ohm catv coax leadin. The tower has an excellent ufer ground, which also grounds the frame of the antenna. The coax shield is grounded at the building entry point. But the catv center wire doesn't seem to me to be protected. I'm not concerned about direct lightning hits; just the EMP from nearby hits, etc.
Perhaps the amplifier has some protection, or will sacrifice itself to protect the TV? Amazon shows a CATV lightning protector, which seems be consist of a 250 volt spark gap. But I fear 249 volts would takeout any TV front end. Any thoughts?
Sincerely,
/blair
P.S. I cut the Cable Company Cord a decade ago. Between the antenna, internet and Netflixs, who needs it?
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cawgijoe
Emo VIPs 
"When you come to a fork in the road, take it." - Yogi Berra
Posts: 5,035
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Post by cawgijoe on May 25, 2016 13:38:41 GMT -5
An antenna mast should be grounded to a grounding rod, usually 8ft that is hammered into the ground vertically. I understand that you can also bury it horizontally, but I've always placed them vertically.
The coax is then attached to a grounding block.The grounding block is also attached by a wire to the grounding rod.
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Post by Priapulus on May 25, 2016 14:14:56 GMT -5
An antenna mast should be grounded to a grounding rod, usually 8ft that is hammered into the ground vertically. I understand that you can also bury it horizontally, but I've always placed them vertically. The coax is then attached to a grounding block.The grounding block is also attached by a wire to the grounding rod. Yes, I've done all that. But what about the center conductor of the coax. The grounding block only grounds the shield. Sincerely /blair |
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cawgijoe
Emo VIPs
"When you come to a fork in the road, take it." - Yogi Berra
Posts: 5,035
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Post by cawgijoe on May 25, 2016 15:11:04 GMT -5
An antenna mast should be grounded to a grounding rod, usually 8ft that is hammered into the ground vertically. I understand that you can also bury it horizontally, but I've always placed them vertically. The coax is then attached to a grounding block.The grounding block is also attached by a wire to the grounding rod. Yes, I've done all that. But what about the center conductor of the coax. The grounding block only grounds the shield. Sincerely /blair The center conductor is screwed into the grounding block. See this article with pics: www.groundedreason.com/how-to-ground-an-outdoor-antenna/ |
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Post by Priapulus on May 30, 2016 17:12:28 GMT -5
I checked with a friend who is an antenna expert (electronics engineer @ Sinclair Antennas). He confirmed that the usual so-called "lightning ground" for CATV coax, only bonds the coax shield to ground. The center conductor isn't protected. It is a safety device (electric shock & fire); not for protecting your TV.
He recommended a grounding device for CATV coax that includes a spark-gap lightning protector between the center conductor and the shield, which fires as 75 volts. So I ordered one and installed it a the building entry point. at the TV, the coax goes thru a Panamax Surge protector, that same that protects the TV. So, layers of protection.
Sincerely
/blair
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