I've been following the Kellems thread and will offer the following
additional comments:
1. Many years of commercial experience have lead to accepted practice
for reliable performance. Kellems grips have been used for years because
they work. Their cost (as I will show below) is really not that great.
Even in Amateur service, we should strive to do our work as well as is
practical. While one might wind wire around coax and use liberal amounts
of tape, when one stands back and looks at the result, I feel something
is missing. When I put something up, I expect it to stay there and work
as intended until I decide to change it (however soon, or later, that
might be!).
I have absolutely no connection to Hubbell Kellems. But I've used their
products for many years and have yet to be disappointed. I want to
recommend these grips to each of you serious tower users.
2. Kellems are not to be found at Home Depot, though. You will need to
find a commercial or industrial electrical supply distributor. Ask any
electrician.
In case you don't recognize the Kellems name, try Hubbell. Kellems is a
Hubbell product now. There is a Kellems catalog---it's perfect-bound and
about 3/8-inch thick, chock full of hundreds and hundreds of these
grips.
Don't count on the counter person at the local electrical supply house
to guide you. You need to identify exactly what model you want, and then
you are likely to have to order it from the Hubbell warehouse. There are
so many of these grips that no store can stock many styles.
3. Kellems grips are made to support hanging cable from one end. They
would be usable at the top of a fixed tower even if the coax is taped
along the tower leg on the way down. But on crank-up towers where the
coax hangs free, there is really nothing like a Kellems grip to hold the
coax without the risk of distorting the coax shape or of slippage. All
grips work like the old Chinese finger trap--the harder one pulls, the
harder they grab the cable.
4. Most of the grips are made for cable larger than the RG-8 style coax;
some accommodate four-inch cable! There is actually a limited selection
of grips for cable under 1/2-inch diameter. But there are some that are
just right!
I support LMR400, 9913 and heavy-duty rotor cable in one size Kellems
grip. I choose to use the type described as "Service Drop Grips." There
are 15 sizes of just these grips to fit cable between 0.23 and 1.25-inch
diameter. The RG-8 cables all seem to be about 0.400-inch and the rotor
cable I use is 0.385-inch diameter. One particular grip is designed to
fit cables between 0.35 and 0.44-inch diameter; this works great!
The most-common style available in this size is Catalog Number 02216003.
It is rated at 500 pounds breaking strength; working strength is lower,
of course, but I doubt any of us would need a stronger grip. If,
however, you feel the need, there is a similar model that uses a
multi-weave mesh and is rated at 870 pounds breaking strength; this is
Catalog Number 02217003.
Both of these grip styles are constructed from tin-plated bronze for
corrosion resistance. There is also a line of galvanized steel grips,
but in fact they tend to rust while the tin-coated bronze grips do not.
The grips are also available in stainless steel as a factory order--not
very practical!
So what will one have to pay for this keen device? Well, the 02216003
grip I described above costs $6.45 each in single-unit quantity.
This grip is described as "Single eye, closed mesh." This means that
there is one supporting eye (it's really a loop of aircraft-like cable
from the mesh but with additional metal crimped around the eye) with a
cable down to each opposite side of the mesh at the top. The coax cable
exits on the centerline of the mesh, about 5.5-inches below the eye. The
mesh itself is about 4.75-inches long.
Closed mesh means that the grip must be placed on the coax from an end.
Best put on before the connector, too. The grips can easily be slid
along the cable by pushing the ends of the mesh toward each other. There
are grips made to attach to cable when the end is not available. More
catalog numbers. And much more expensive; but avilable.
So, is it worth $6.45 to firmly grasp the end of each coax or cable
hanging from your tower? Only you can decide! One roll of 3M Type 130C
Linerless Rubber Splicing Tape costs $6.83 from the same supply house.
Scotch Supper 88 costs $3.84. Extra trips up and down the tower make
these costs seem kind of puny!
5. Try to get your electical supply house to give you a Hubbell Catalog
2000; it's a one-inch tome and includes the Kellems grips. There is also
a Kellems grips catalog, but the supply house might not have these. You
can look in your Yellow Pages for the nearest Hubbell distribution
center (read Hubbell warehouse) and request one; they have been very
accommodating to me.
Hubbell has a website: http://www.hubbell.com or you can go directly to
the Kellems web area at http://www.hubbell-wiring.com. But don't expect
to find the catalog or many detail pictures there. There is provision to
request a catalog by E-Mail, though. Be business-like!
6. For many of you, this will definitely be "more than you ever wanted
to know." But, judging from some reflector comments, some of this
information may not be widely known. I hope to help those folks who are
interested.
Again--I'm not selling or promoting anything. But I enjoy a job well
done and I believe Kellems grips do their job well.
Best wishes and happy climbing to all,
Larry McDavid W6FUB
lmcdavid@lmceng.com
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