[Elecraft] Antenna feedline Placement

[Don Wilhelm]

Jim and all,

Stuart brings up a good point about the use of spacers.  BUT that will work
well only if the conduit is of substantial diameter - I would personally
prefer to use 3 inch diameter or greater for the 'one conduit' solution.

If small diameter conduit is preferred (asthetics, abiliy to seal against
weather, etc.) then using separate conduits for the ladderline and the coax
would be a better solution.  A ground wire (wide strap is better) could live
in the same conduit as the coax with no concern.  The conduit for the ladder
line should be plastic, but the coax doesn't care.

73,
Don W3FPR

----- Original Message ----- 
From: "Stuart Rohre" <rohre@arlut.utexas.edu>


> You can make foam spacers for holding ladder line away from other feeders
> and wall of conduit.  The plastic conduit will have the least effect.
>
> A large diameter metal conduit, that fulfills the spacing suggestions on
> ladder line, (using the foam spacers) can offer an increased lightning
> advantage.   It can function as a waveguide beyond cutoff filter if
> adequately grounded outside.  It may depending on its length of run, even
> cut down on electric noise getting to the shack on the outside of the coax
> shield.  As far as the coax is concerned, it will not "see" the parallel
> line, as its RF field is contained between the inside of its shield and
the
> center conductor.
>
> For the diameter that a ham could typically do for the conduit, you would
be
> better off using plastic.
> But the spacers are a great way to maintain constant effect of the
> dielectric of the plastic upon the parallel line balance.
> -Stuart
> K5KVH
>
>