[TowerTalk] good,bad,ugly opinions on coax in or out

Roger (K8RI) on TT K8RI-on-TowerTalk at tm.net
Mon Aug 22 02:07:34 EDT 2016


Once my ground system was finished for the 100' 45G  with a mast 
supporting a 5L tribander @ 100', 7L C3i 6-meter Yagi with a 29'6" boom 
@ 115' with a cross boom supporting a pair of 12L C3i 144 MHz antenna 
and a pair of 11L C3i 440 antennas @ roughly 130 feet, the tower and 
antennas took 3 visually verified direct strikes per summer, except 
one.  The only damage was the summer before the ground system was 
finished,. There were two, long UHF TV antennas with preamps. one at 90' 
pointed SSE and one at 95' pointed roughly NW.

Rarely were the rigs disconnected.  I had no damage to any equipment 
after finishing the ground system even with direct hits to the antennas 
and/or tower.  Coax shields were grounded at both the top and bottom of 
the tower using bulkhead connectors. Cable entering the house passed 
through Pollyphasers  mounted on a grounded plate at the SPG.

Coax and the rotator cable were taped to one tower leg, on the outside 
of the tower.
Coax from the wire antennas connected to a remote switch mounted at 
roughly 20 feet on the tower.  The switch is configured to short the 
unused cables and ground all shields.

The lightening did remove all the silver plating from some of the 
connectors, leaving the brass looking like it had been sand blasted.  
Even though all the water proofing was removed, there was no moisture  
ingress as I flood all connectors "up top" with DC-4, or 5 compound,

NOTE: The ground system consists of a network of ~600 feet of bare #2 
with 32, or 33, 8' ground rods, CadWelded to the bare #2

73

Roger (K8RI)


On 8/20/2016 Saturday 7:05 PM, w5jmw at towerfarm.net wrote:
> I had a lightning hit.Not bad but somewhat costly.A rcs-8,cde rotor 
> box and a cushcraft ar270b.Seems to have hit the vertical as all coils 
> are gone incliding the base matching.The tower is down for repair.At 
> this point I am bringing the coax down the tower.The switch had been 
> at the top with one feedline.The feedline was run outside the tower 
> with coax stad-off.rotor and ctrl lines inside the tower.So my 
> question to the group.It is better,or worse for the coax to run inside 
> or outside..73 and in advance,Thanks to all...john W5JMW
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