[TowerTalk] Coax Grounding on a tower.

K8RI on Tower talk k8ri-tower at charter.net
Mon Jun 26 22:02:13 EDT 2006

Due to basement work I've had to pull all the cables out of the conduit. 
Man, but I was sore the other day and was wondering whey until I realized 
I'd pulled between 1300 and 1500 feet of cable out of conduit the previous 

This has put me off-the-air with the main station which is probably why 
6-meters has been open the last couple of weeks.

As this is turning into a rotator repair (It's hanging up again and the 
thrust bearings are free), antenna repair, antenna removal, replace the pig 
tails, and reroute the coax project I've decided that as long as the coax 
has to go through connectors at the end of the pigtails at the top of the 
tower I'm going to mount an aluminum angle across the face of the tower with 
3" UHF feed throughs.  Each of the current 4 pig-tails will fasten to a feed 
through which will ground the brade to the tower at the top. The cables then 
run down the inside of the NE tower leg where they are joined by two more to 
the base and loop up into the junction box where they enter the 3" conduit 
to the house.  The cables will be jointed by at least one or two more part 
way down the tower, but there may be two less from the top.  The easiest is 
to just say the number may vary.

My thoughts are to either use another set of bulk head connectors on 
Aluminum angle bracketed to the tower as at the top, or to clamp those 
brackets to the leg of the tower using a hose clamp and spacers so the 
center part of the feed through will be grounded to the tower leg.

This will add one more set of connectors to the cables but from experience 
and information gleaned from TT I'd say the insertion loss of the one extra 
connector is going to be almost non existent. In addition the cables will be 
grounded to the tower where they are leaving the tower.

The new junction box at the house entrance will be putting the shield 
grounds and the Polyphasors (sp?) right outside  the house at the point of 
entry where they are currently just inside the house.  I think this will be 
an bit of an added safety feature.

One leg of the tower ground system will be entering the Hoffman box beside 
the conduit, grounding the back plate inside and then continuing into the 
house with the other cables. This #2 runs directly through to the house 
ground for the electrical service as it's the only way I can get it there. 
I'd have to tear up a rather expensive garage apron to get there outside and 
that would make the grounds different length.

This is going to get rid of the conduit coming through the basement wall. 
It'll come in through the end plate of the floor joists and there will be no 
cables showing below the basement ceiling.  At least that is the plan.

Remember it's normal for this installation to take at least three lightning 
hits a year and I think it's already had it three (or more) just in the last 

Any socially acceptable suggestions?


Roger Halstead (K8RI and ARRL 40 year Life Member)
N833R - World's oldest Debonair CD-2

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