Yep, good stuff. Be sure of your budget before buying a roll. It is a
bit pricey. Handles legal limit HF power with a reasonable SWR.
73
Bob, K4TAX
On 2/6/2016 7:10 PM, Robert Nobis wrote:
I have used RG303/U for chokes. A bit smaller diameter than RG400 (0.170
versus 0.195 inches). RG303/U has a solid copper center conductor that is
silver plated. The shield for RG303 is also silver plated copper. The jacket
is Class 9 Teflon. Also the dielectric material is teflon.
73,
Bob Nobis - N7RJN
n7...@nobis.net
On Feb 6, 2016, at 17:49, Guy Olinger K2AV <k2av....@gmail.com> wrote:
If one wants a small 50 ohm coax that will take QRO with a very large
margin and was *designed* for bending and use in aircraft wiring harnesses
then use RG400 to wind around your core. RG400 uses a fine stranded
silvered copper center conductor that is more flexible than its Teflon
dielectric. It has a double shield made from silvered copper strands.
That's silvered strands whose silver sulphide patina or tarnish is
conductive as opposed to the green copper sulphate that separates copper
strands that have been water soaked.
Wind the coil form with RG59 to get the length and buy just what RG400 you
need. You can buy brand new RG400 by the foot. With the Teflon dielectric
you can solder the RG400 without worrying about melting it.
Do it with the good stuff to start with and put it in your will.
73, Guy K2AV
On Saturday, February 6, 2016, Ron D'Eau Claire <r...@cobi.biz> wrote:
Bob makes an excellent point. I've seen cases where even "solid" dielectric
did that over time because, after all, it is not really solid. The
dielectric is plastic so the coax can be bent.
All coax has a minimum bending radius specification. Specific data is
available on line but, in general, RG58 size cable usually has a minimum
radius of 1 to 1.5 inches (2.5 to 3.8 cm) and RG8 size cable has a minimum
radius of at least 2 inches (5 cm). Note that is radius. If you curl the
cable into a circle the minimum diameter of that circle should be at least
twice that or 3 to 4 inches (7.5 to 10 cm).
It's not something I've found especially critical in HF applications at
least around my shack, but tighter bends, which may not actually cause a
short (yet), alter the impedance as the center conductor migrates toward
one
side so it is no longer equally spaced within the shield. This can be a
serious issue in microwave and even UHF installations.
73, Ron AC7AC
-----Original Message-----
I would have concern that long term usage of RG-8X, being foam core
dielectric material and bent in a tight radius, may allow the center
conductor to migrate to the inside radius of the bend. The Minimum Bend
Radius for RG-8X is 2.50". Thus the tight bend will allow the center
conductor to short to the shield. A solid core dielectric coax such as
RG-303 is much preferred.
73
Bob, K4TAX
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