Grounding Coax Shield

Joined
May 27, 2018
Messages
164
Location
Jefferson City, Mo
#1
I'm sure this has been covered before but after searching for a while I couldn't find a specific answer.

I've read that you should ground the coax shield at the entry point to your home. For obvious safety reasons but also to help get rid of static charge from wind hitting the antenna.

What is the best way to make the connection to the coax shield? Will using a surge protector such as a Polyphaser connected to a ground wire/ground rod accomplish this?

Thanks!
 
Joined
Jun 16, 2013
Messages
3,202
Location
Texas
#2
There is a kit called a grounding kit. However, personally (professional opinion) you rise more damage to the shield braid attempting to install a ground kit on braided feedline. A properly grounded polyphaser inside the building and a DC ground antenna meets basic and enhanced grounding standards.


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Joined
Jun 30, 2006
Messages
7,195
Location
So Cal - Richardson, TX - Tewksbury, MA
#6
Grounding the shield usually does nothing for static buildup on the antenna as the static is a potential between the shield and center conductor. There are various was to drain static off coax like a specific value RF choke across the coax and 75 to 100uh is common for general HF use or much smaller values for the VHF/UHF bands. Sometimes you can use a high value resistor across the coax and I've seen values between about 100k ohms to 1meg ohm.

A Polyphaser lightning arrestor will usually not have any effect on static buildup until the level gets to whatever Polyphaser has chosen for the arc over voltage, which can be several hundred volts. A gas discharge type arrestor can be had in various voltage ratings with about 90V being on the low side.

For connecting the shield to a ground rod you might visit the National Electrical Code and specifically article 810 which deals with antenna grounding.

I'm sure this has been covered before but after searching for a while I couldn't find a specific answer.

I've read that you should ground the coax shield at the entry point to your home. For obvious safety reasons but also to help get rid of static charge from wind hitting the antenna.

What is the best way to make the connection to the coax shield? Will using a surge protector such as a Polyphaser connected to a ground wire/ground rod accomplish this?

Thanks!
 

nmelfi

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Premium Subscriber
Joined
Apr 24, 2011
Messages
262
Location
Travelers Rest S.C.
#7
Maybe I am missing something here, but my radio is connected to the house ground with that block and so is my antenna. What am I missing. Seems cable and sat companies do it that way so please explain.
 
Joined
Jun 30, 2006
Messages
7,195
Location
So Cal - Richardson, TX - Tewksbury, MA
#8
What I believe you have would meet code for a satellite antenna or cable TV entry point. It probably wont reduce static or protect you from a direct lightning hit, but it does put the coax cable at the same ground potential as your main house ground and that is what NEC is about.

A problem comes up when you pound in a new ground rod and connect radios or coax to that, without bonding the new ground rod to the main house electrical ground per NEC. That can be dangerous and generally causes more damage in a direct lightning hit.

Maybe I am missing something here, but my radio is connected to the house ground with that block and so is my antenna. What am I missing. Seems cable and sat companies do it that way so please explain.
 

tdeater

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Premium Subscriber
Joined
Nov 24, 2003
Messages
46
Location
Fremont, MI
#12
Yes, a polyphaser that is connected to ground will ground the shield of your coax but not the center conductor. As for bleeding off static and such, it would bleed it from the shield itself, but not the center conductor.
 
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