Extra Coax?
 

Just curious... Seems to me I read somewhere that extra coax between
antenna and radio should not be managed in a coil. Any truth to this? If
so, what's the issue?

I've got an attic antenna about 20 feet or so from an ICOM R8500 connected
with 50 feet of RG6-U. This leaves about 30 I keep coiled and wire tied on
the floor.

Thanx,
Bob

Bob wrote:
"This leaves about 30 I keep coiled and wire tied on the floor."

RG-6 has a loss of 0.8 dB per 100 feet at 10 MHz. At h-f, you will be
hard pressed to measure the loss in 30 feet of RG-6.

A coil of surplus coax only deters r-f current on the outside of the
coax which helps avoid surges and radiation on the coax.

Use non-conducting ties on the coil.

Best regards, Richard Harrison, KB5WZI

Bob wrote:
Just curious... Seems to me I read somewhere that extra coax between
antenna and radio should not be managed in a coil. Any truth to this? If
so, what's the issue?

Extra *ladder-line* should not be coiled up. For coax, coiling
actually reduces the common mode current which is a good thing.
There is some attenuation in the length of coax used for the
coil but if the proper coax is chosen and the SWR is low, those
extra losses will probably be negligible.
--
73, Cecil http://www.qsl.net/w5dxp



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Just curious... Seems to me I read somewhere that extra coax between
antenna and radio should not be managed in a coil. Any truth to this? If
so, what's the issue?

I've got an attic antenna about 20 feet or so from an ICOM R8500 connected
with 50 feet of RG6-U. This leaves about 30 I keep coiled and wire tied on
the floor.

The only issue is that if the diameter of the coil is too small the
interconductor will cut through the insulation and short to the shield over
a period of time. If you coil it with an inside diameter of a foot or more
then you will be fine.