> What is the difference between real and un-real RG214?
There are some non-mil-spec RG214 varients out there. Sometimes they are
labeled as "RG214 TYPE", or "RG214 Commercial". These typically have double
braid like "real" RG214, but unlike "real" RG214, the braids are bare copper
instead of silver-plated. Bare copper braid gets noisy as it ages, as the
oxide layer formed on the braid strands isn't a good conductor, unlike
silver which, even when oxidizes, is still a fairly good conductor.
Wacom was one of the bigger companies that used "RG214 TYPE" cables in their
VHF duplexers, at least for a while. Has caused me substantial grief. Most
of their UHF/800/900 products used RG-400.
> And what is the problem with RG-142?
RG-142B/U has a center conductor that is copper-clad steel with a silver top
plating. The potential problem with RG-142B/U is that the steel center
conductor can break due to repeated flexing. This isn't a problem in fixed
installations, but can be a problem if you're using it as a test cable or in
other situations where it's subject to repeated flexing. The most important
thing to do is make sure you don't knick the center conductor when removing
the dielectric when installing connectors as that greatly increases the
chance of it breaking. But, I have to say in many years and hundreds
(thousands?) of feet of use, I've never had it happen to me personally, but
then again, I only use it for fixed installations. For test cables, use
RG-400, which is virtually identical to RG-142B/U, except the center
conductor is stranded so it handles flexing better.
Good cables for repeater installations (assuming they're mil-spec or
otherwise not some kind of a knock-off varient) in order of increasing
diameter include: RG-142B/U, RG-400, RG-223, RG-393, RG-214, and any
Heliax-type cable with a solid copper shield.
Cables to avoid: anything with a bare copper braid (even if
double-shielded), any cable with foil+braid shield, anything that isn't
double-shielded or solid-shielded.
--- Jeff WN3A
