Feedline protection

EJEDWARDS.OPPD.GOV EJEDWARDS@oppd.gov
Mon, 6 Jan 1997 10:48:21 -0600


--Boundary-929389-0-0

W5FL wrote: 
>>Polyphaser says to ground the shields of the coaxes at the base of the 
tower, but says not to use non hard line coax because moisture gets in when 
you remove the pvc jacket to ground the coax shield.<< 
 
After learning about advantages of grounding the shield, I decided to do this 
to my RG-8 type coaxials going to my roof mounted vertical & sloper (No 
tower...yet!).  I was very concerned about breaking the insulation or braided 
shield.  Once I got the 2 grounding kits and looked them over, decided to 
"just do it".  Well I'm into the second winter with them on and no problems so 
far.  The weatherizing compound and tape were really good quality.  I'd be 
surprised if any moisture were to get in.  One thing I'd get next time is the 
liquid copper compound sold by PolyPhaser to put onto the braided shield for a 
better seal & connection.  Also, installed PolyPhaser units on the coaxials at 
the entry into my basement.  Nothing more to report 8^) 
 
73, 
de ed -- k-zero-i-l 
 



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Received: 04 Jan 1997 23:57:43                    Sent: 04 Jan 1997 22:49:12
From:"Wendell - W5FL " <owner-towertalk@paris.akorn.net>
To: towertalk@contesting.com
Subject: Feedline and control line protection
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Thanks for the response to my request on wire size for grounding and =
rebar welding and grounding.  If anyone still has any input on this =
previous message, looks like I am going to be delayed a few days with =
freezing weather again next week so pouring concrete looks like mid next =
week or later.  (Frost line is still about 1 inch for those with real =
wx)

Now I am concerned with the three coaxes (RG173/u or Times LMR400), =
three 8 wire control cables for rotator and switches, etc.  Polyphaser =
says to ground the shields of the coaxes at the base of the tower, but =
says not to use non hard line coax because moisture gets in when you =
remove the pvc jacket to ground the coax shield.  They have very little =
to say about the control lines and they should be important, also.

Question 1:  Do I need to do anything to these coax and control lines if =
they are going to go to some form of lightning arrestors about 100 feet =
away where they go into the house?  I guess if it is really important to =
ground the shield, I can use a box with feedthroughs and put PL-259 =
connectors on each side with drip loops.  I have never had much luck in =
keeping the moisture out of this type of arrangement, though.

Question 2:  Has anyone any suggestions on the least expensive (but =
good) way to protect these coax and control lines where they come into =
the house?  Is any protection required at the rotator or switchboxes?  I =
was going to put a home weather station about 30 feet up the tower, but =
will each of these additional control lines (14) also require protection =
at the unit or base of tower and going into the house?

Any and all assistance appreciated.  It has been 18 years since I put up =
my last tower in San Diego and the lightning protection field has =
changed considerably from one ground rod at the base of the tower!


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