Dave, Belden 9913 was one of the first low loss "RG8 sized" coaxes to come
along. It had the foil/braid outer conductor and a spiral of polyethelene
between the outer and inner conductors that made the dielectric partially
air for low loss.. Unfortunately, it also created the "garden hose effect",
where if water got in a connector it could run all the way down inside the
coax. Belden made a low loss foam RG8 before 9913 called 8214.. I think it's
still made, but the specs on LMR400 are better.. probably because of better
foam and the foil shield. Times came out with the LMR line and there are a
lot of copycats of the LMR cables and the Belden 9913. Belden also makes a
foam 9913 (or they did) called 9913F.. Sheesh it's confusing.. But the LMR
cables are pretty much the best (lowest loss and most reliable) for a given
diameter until you start talking about Heliax cables.. The original LMR400
(and 240 and 600 and 900 etc etc) have a solid center conductor (copper
plated aluminum) and a stiff shiny outer sheath over the braid/foil outer
conductor. The LMR400UF (ultraflex) has the same dimensions but a stranded
center conductor and a more flexible outer sheath.. It is MUCH MORE flexible
than straight LMR and the specs are close to the same. Very good for around
a rotor. It costs more of course. Connectors are pretty easy to get for the
LMR400 cables (and 9914/8214 and all the clones). The normal RG8 N
connectors (UG21) will fit with a different center pin (the center conductor
on the low loss cables is slightly larger to maintain 50 ohm impedance with
more air in the dilectric - dielectric constant on LMR and 9913 is in the .8
range where RG8 is in the .66 range).. there are also special connectors
made for LMR400 that mount sort of like PL259's.. there's a TON of stuff out
there..
If you want low loss RG8 sized coax, I would try to stick with LMR, or one
of the Belden foam cables. LMR is probably the most readily available..
there's my $.02 (or maybe $.03.)
bill, k1dy
_________________________________________________________________
http://newlivehotmail.com
_______________________________________________
VHFcontesting mailing list
VHFcontesting@contesting.com
http://lists.contesting.com/mailman/listinfo/vhfcontesting
|