One wishes to leave slack in one's outdoor cables in case we
reposition things one day, or a typhoon.

We hear it is a big no-no to concentrate this slack all into a loop
several turns thick, creating an inductance (except for the one loop
right below one's 2-meter GP antenna.)

OK, we will distribute this slack evenly along the 80 meter run of
RG-213, nice if a tree gets blown over on it.

But too much slack looks goofy snaking along the nylon support cord.
How much slack is right? And in what formation shall we distribute it?

On Fri, 11 Mar 2005 01:10:32 +0800, Dan Jacobson
wrote:

One wishes to leave slack in one's outdoor cables in case we
reposition things one day, or a typhoon.

We hear it is a big no-no to concentrate this slack all into a loop
several turns thick, creating an inductance (except for the one loop
right below one's 2-meter GP antenna.)

OK, we will distribute this slack evenly along the 80 meter run of
RG-213, nice if a tree gets blown over on it.

But too much slack looks goofy snaking along the nylon support cord.
How much slack is right? And in what formation shall we distribute it?


I would think that the best thing you can do is evaluate your
possibilities. Look over your site and figure out your risks and how
the coax may be affected if a wind blows or a tree sways or a limb
falls. I don't believe that coiled coax will hurt your signal, but it
will be twisted and/or kinked if a limb falls on it or it is otherwise
stretched out due to a disaster.

One thing I learned the hard way is to create a break-point in the
line where if something grabs the coax and keeps going with it, it
releases from the radio it is attached to. In my case, I have a board
through which the coax runs but the radio can't pass through. IF the
wire is pulled from the back, it will break loose from the connector
before taking my rig with it.

Good luck.

Buck
N4PGW

--
73 for now
Buck
N4PGW

On Thu, 10 Mar 2005 14:48:52 -0500, Buck wrote:

One thing I learned the hard way is to create a break-point in the
line where if something grabs the coax and keeps going with it, it
releases from the radio it is attached to.

Hi Buck,

Reminds me of my Navy days when Ensigns would attempt to walk 6 feet
with a mike that had a 5 foot cable. We attached a chain from the
mike to the bulkhead that was 4 foot long.

Answer for appropriate cable slack: 1 foot.

73's
Richard Clark, KB7QHC

Got a great answer from someone who perhaps preferred to be anonymous:

There is no problem coiling up excess coax. As long as you don't coil it too
tight. There is a 6" minimum bend radius for RG-8 size cable. The inductance
thing is something someone got garbled. Coiling it up will create inductance
for signals flowing on the outside of the coax. This is called a choke balun
and is commonly used at the feed point of the antenna. It has no effect,
other than the length of the cable adds a little loss, to the desired signal
that is flowing on the inside of the cable. Remember in coax the desired
signal flows between the inside of the shield braid and center conductor.
Any signal flowing on the outside of the coax has no use and may be
undesirable. This is why you can tape coax to masts and bury it underground
with no effect on the signal. On 80m there is not always a reason to cut the
cable just long enough to reach, but on VHF/UHF excess length just means
more loss in the coax and is not desirable. Also if you have a lot of extra
coax coiled up and you are using a tuner to say make the 80m dipole work on
30m the extra length could cost you something. For example I use my
160/80/40/30 dipole array on 60m (5MHz) band. The Z of the antenna is
something like 388-j1200ohms. This high SWR increases the loss in my coax by
allot on 60m. In fact the loss is 7.5db. This means my 100 watt is reduced
to 18 watts at the antenna. If my feed line was shorter the loss would be
less of course. So in this case if I had a lot of extra feed line, short[en!]ing
it could really improve my signal strength.