Scotchkote used to be used in the military 50 years ago but technology has
brought out better products.Steve, WD8NPLSent via the Samsung Galaxy S10e, an
AT&T 5G Evolution capable smartphone
-------- Original message --------From: Jeff DePolo <jd0@broadsci.com> Date:
4/4/19 12:12 PM (GMT-05:00) To: 'Keith Dutson' <kdutson@sbcglobal.net>,
'towertalk reflector' <towertalk@contesting.com> Subject: Re: [TowerTalk]
Liquid Electrical Tape? > I have heard the best is 3M Scotchkote. However, I
recently > inspected a> coax connection on the outdoor 2 meter cable running
from repeater to> antenna (on top of 500 foot building). It had been slathered
with> Scotchkote after sealing with two wraps of 88, one wrap of > 2228 fusion
tape> and two final wraps of 88. It appears the Scotchkote was > useless in
the> harsh outdoor environment at 500 feet. ... > 73 Keith NM5GScotchkote was
never meant to be used as a "final coat", which,unfortunately, is how it is
most-often misused. It is supposed to be usedbetween alternating layers of
electrical tape (Scotch 33+, Scotch 88). Ithas no UV resistance, and as you
saw, it just dries up, cracks, and becomesuseless if used as an outer coating.
Scotchkote is also a big ugly mess todeal with up on a tower, especially if the
wind is blowing; you may end upwith more of it on you than on the
connection.Unless there is a real good reason to do otherwise, we stick with
the triedand true "tape and taffy" method, starting with a "courtesy wrap" of
regularelectrical tape, then mastic tape (aka butyl) squeezed and massaged to
makesure that there are no air voids, and forming it to yield a smooth
contourover the connection and tapering down to the cable diameter, and then
threewraps of electrical tape (regular 3/4" Scotch 88 for small cables, 1-1/2"
or2" Scotch 88 for larger diameters), one winding up, one back down, and
oneback up again. You don't want to use a big wad of mastic, just enough
tocover the connection and smooth out any irregularities. If you use toomuch,
or if you make the final vinyl tape wraps too tight, the constrictiveforce of
the electrical tape wraps will cause the mastic to ooze out on hotsummer
days.The alternative that I prefer, but most tower crews don't have the
patiencefor, is using multiple layers of splicing tape (Scotch 130C, Scotch
23,Plymouth "Plyvolt", etc.) instead of mastic. Still use a courtesy
wrapfirst, and finish with three layers of 88 for UV protection. The
splicingtape has to be stretched as it is applied in order for it to properly
bondto itself.For things like omni antennas where the connector is recessed up
into thebottom of the mounting pipe, or yagis where the connector is very close
tothe boom or other structural element, it can be damn near impossible to
usetapes to seal the connection. High-grade thick-wall adhesive-lined
heatshrink is the best alternative, with Canusa being the preferred
brand.Canusa CFTV series is pretty much the de facto standard in the cable
TVindustry for outdoor weatherproofing, and that's what we use. Canusa
heatshrink is designed to be shrunk using a propane torch, so installing it on
atower even with wind blowing at moderate speeds isn't a problem.We've also
been using "Rayvolve" spice covers from Raychem/TE for fiberconnections and the
like. We haven't been using them long enough for me toform a definitive
opinion of them yet.Despite the advertising campaigns in recent years,
silicone-based tapes like"rescue tape" aren't anything new. Personally I
haven't found a reason touse it for weatherproofing coax connections given the
other existingalternatives. YMMV. --- Jeff WN3A---This
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