TT:
A couple of years ago a squirrel (and I know which one he is) chewed
through the outer jacket of all three of my tower's coax runs near ground
level. I taped them up as well as I could at dusk one day, but later found
that I had missed a few open jacket spots. The SWR on the antennas would
bounce all over the place when I ran near 100 W; I'd have to back down the
power to get a stable SWR reading. The braid I could see through the jacket
was darkened by corrosion.
I plan to replace all three coax runs to do the repair correctly
WIGATI. In the meantime (today), I cut off the bottom five feet of each
coax run and replaced it with a short jumper, a new crimp-on (I'm a big fan
now) PL-259 on the old cable end and a PL-258 barrel connector. Before I
cleaned up at the tower, I decided to take apart the homebrew shield
grounding connection to see how it stood up to time (I installed the tower
and cables in 2001.) I posted about the HB copper flashing connector at the
time and subsequently:
http://lists.contesting.com/archives//html/Towertalk/2011-03/msg00337.html
.
I found that the outer layers of self-amalgamating tape and 3M 33 tape
(one layer and 3 layers, respectively) were tough to cut through with a box
cutter (I cut my finger only once, though) but I was able to peel them off
once they were opened. The mastic was another story. It had flowed into
the open edge of the copper flashing and into the copper coax braid above
and below the edges of the flashing. Fortunately about 80 -90 % of the
inside of the flashing was untouched by the mastic and, presumably, made
good contact with the shield braid all this time. The mastic was impossible
to get off the SS hardware and the flashing, though, so I'll have to discard
those materials.
In the future I will not use the mastic as a first layer. I'll
probably use a layer or two of 33 or 88 tape and THEN use the mastic pad to
cover the connection and the bulges around the nuts and bolts and to seal
the gap between the coax jacket and the ground wire. I would then finish
with three wraps (up/down/up) of 88 tape then a single layer of
self-amalgamating tape.
I have concluded that:
O The mastic tape does a good job in its intended purpose - permanently
protecting electrical power connections and other energized materials. It
is NOT intended to be re-entered.
O I would not recommend trying to undo this type of connection up on a
tower while being held in place by a climbing belt or harness. I was
pushing back from the connection too much while I was opening the connection
with a knife on the ground; that's too much risk for me aloft.
O I'm getting old. My hands are sore from taping over the 3 new
PL-259/258 splices. Each splice was three wraps and each wrap was about 27
turns of tape while keeping tension on the tape roll.
I have photos but haven't put them up on my Photobucket account yet.
That'll have to wait until 2017. Happy New Year to all.
73 de
Gene Smar AD3F
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