I think this is, or should be, a repeater-builder FAQ.
Foil+braid cables like 9913, LMR-series, etc. should generally NOT be used
in duplex environments. Although a few may report results to the contrary,
braid-over-foil cables produce noise due to the dissimilar metal contact,
particularly as the cable ages/weathers. As such, they should be avoided.
Double-silver-shield cables such as RG-142B/U or RG-400/U are RG58-sized
cables good for short runs at UHF and below. Their use at 900 or above
should be kept to very short lengths and/or power levels under 100 watts due
to the losses involved. RG-393 is slightly smaller in diameter than RG8 and
is constructed using dual silver braids like RG-142B/U and RG-400/U, so it
is good choice for longer runs and/or higher power levels. RG214/U is also
a good choice except at very high power levels as, unlike the others cited
above, it has a solid polyethylene dielectric instead of teflon. RG-223 is
a smaller version of RG-214, again with a double silver braid and poly
dielectric. Be careful when ordering RG-214's. There are "commercial"
grades of RG-214, as compared to mil-C17 types, which have bare copper
braids instead of silver plated. Bare copper braids, even if
double-shielded, should be avoided for the same noise-generating reasons as
in the case with foil+braid cables.
Solid-shield cable such as Superflex-type Heliax (FSJ1-50A 1/4", FSJ2-50A
3/8", FSJ4-50B 1/2") is the best in terms of both loss-versus-size, lack of
duplex noise, and shielding properties.
Hope this helps.
--- Jeff
> -----Original Message-----
> From: [email protected]
> [mailto:[EMAIL PROTECTED] On Behalf Of Howard Z.
> Sent: Wednesday, June 06, 2007 5:13 PM
> To: [email protected]
> Subject: [Repeater-Builder] Which coax cables to use with repeaters?
>
> I have read that one should use dual-shielded cables.
>
> Which cables are these?
>
> Is Belden 9913F7 a good choice?
>
> Here is its description: http://www.therfc.com/9913f.htm
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> Yahoo! Groups Links
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