> Several years ago I had to replace all the insulators in the bottom set of
> guys on my Rohn 25 series-fed 160 m vertical due to a lightning hit that
> pulverised every single insulator at the bottom guy level. Originally,
> the guy insulators were attached using three u-bolt cable clamps at each
> termination plus serving the strands, per the Rohn book. With the
If you are refering to wrapping the individual metal strands, step wise
fashion no additional clamps are needed. That is about as neat and stong a
connection you can get. U-bolt clamps in general form a spot that is
slightly weaker than the adjacent cable.
> replacement insulators I used Big Grip pre-forms instead of cable clamps.
> As I recall I, purchased the Big Grips from Texas Towers. They arrived
> no written instructions whatever, but it appeared pretty obvious how they
> went together so I installed the new insulators with no difficulty.
I've had several shipments of the things and so far as I recall each
shipment came with a data sheet. The sheet was with the rest of the
paperwork as I recall. HOWEVER I received the guyline in the same shipments
and the information for the Big Grips *may* have come with the guy line
instead of the Big Grips themselves.
> Now, I have just recently read for the first time on a couple of websites
> that I ran across, that with the type 502 insulators I used, you are
> supposed to begin wrapping the grips at the SECOND set of paint marks,
Some Big Grips have two marks, mine in both sizes _only_have_one. The marks
are to aid in the wrap starting point depending on the size of the thimble,
or insulator. Larger thimble or insulator needs the wrap to start farther
To answer the one question, which I accidentally snipped, Yes, starting the
wrap too close to an insulator so that the Big Grip "pinches" the corners of
the insulator can cause stress. With insulators being some what fragile it
is something to be avoided as any additional stress is an additional point
for failure. When that stress point becomes... well... a point the
likelyhood of failure goes up.
Of course that is why insulators are designed so that should the insulator
fail completly the two cables are still in a fail safe configuration with
each looping through the end of the other.
Roger Halstead (K8RI and ARRL 40 year Life Member)
N833R - World's oldest Debonair CD-2
www.rogerhalstead.com (Use return address from home page)
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