> The inner foil should be bonded directly to the dielectric surrounding
the
> center conductor. Otherwise, the cable will have an outdoor life
issue. I
> can't recall the last cable I saw without the innermost foil bonded to
the
> dielectric. I suppose someone somewhere makes bad cable that will wick
> water
> or trap moisture in that critical area. Normal reasonable quality
cable
> has
> a bonded foil, meaning the foil is bonded directly to the center
> dielectric.
There is some non-bonded foil cable out there. I don't like it as it's
much more difficult to properly terminate. Much of the bonded cable also
has a backer on the foil though -- if you remove the foil on that type
there is commonly a blue film on the "back" of the foil. It might be a
remnant of the adhesive, I'm not sure about that. My point was that even
if there is a plastic film on the foil, it would be on the side of the
foil that isn't in contact with the braid anyway.
> There is a triaxial cable that has a layer of insulation between
shields,
> sometimes Mylar, but that is outside the innermost shields.
Sounds a bit like RT-142 that has a separator between the braided
shields.
> As hard as we look for something wrong with CATV cables, there is very
> little to find wrong. Other than susceptibility to very low frequency
> energy, which doesn't bother us unless lightning opens the foil, it is
> great
> stuff.
Personally, I've even used fully non-flooded "regular" CMR-type RG6
cabling direct buried with no problems for 15+ years. I would *not*
recommend that (I was in a hurry way back then and didn't have the
correct cable), but it can work. I prefer the polyethylene-jacketed
flooded RG6 for outdoor use. It can also be easily found in orange which
makes it easier to find when digging holes, but note that the orange
jacket doesn't hold up nearly as well in sunlight as the black jacket.
It's also possible to get RG6 with a solid copper (BC) center conductor
instead of the more common copper clad steel (CCS) center conductor. You
need to get the RG6 types for security (CCTV) systems, or for
direct-broadcast satellite systems. Both of those tend to have the BC
center conductor for either the low-frequency composite video (for
security cameras) or DC power for the LNB (for satellite). Cost is
higher and availability lower for those cable types, unfortunately.
-Bill
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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