[Antennas] SWR Isn't Enough - Working in a high SWR setting

[B. Joseph Giacobello]

Jim, just out of curiosity, what's your objection to copper clad steel?  I
always thought it was acceptable for RF applications.

73, Joe

Mike J Maloney wrote:

> HI Jim,
> Comments inserted below.
>
>    Would you mind sharing some
> > tips on
> > how to get the most out of ladder line?  For instance, could you
> > give me
> > ideas on what to consider when making long runs of 450 ohm windowed
> > ladder
> > line?
>
> For long runs, I would not get the 450 ohm "windowed" ladder line.  It is
> more of a glorified twin lead using copper clad steel for the conductors.
>   For lowest loss make your own from 1/2" polyethylene irrigation  tubing
> spacers or get from www.w7fg.com.
>
>  What should it not be near?  How does one get it around rain
> > gutters?
> > etc.  What tips do you have for stand off insulator ideas?
>
> Black polyethylene or plexiglas stand-offs, or nylon weed eater line thru
> spacers to tie off or hold taut. Keep 2-3 times or more spacing away from
> metal downspouts, guttering, metal window screens, etc.
> >
> > Also, any tips on 'feed thru' approaches (e.g. into the shack).
>
> Bring it thru the wall(if composition material)  to interior wall, using
>  binding posts or banana jacks for quick disconnect for lightning
> isolation.    If squeemish about going thru wall, replace a window pane
> with plexiglas panel fitted with banana jacks.   Bring open wire feeders
> direct to balanced tuner output.   Coax from 50 ohm tuner input to rig.
> Balun not needed with the proper coupler.   If not, use a coil choke
> balun on low Z input side.
>
> I believe big closed horizontal loops make the best all band simple
> antennas.  See April 2002, QST p.47. If space and conditions dont allow a
> big loop, then a center fed doublet is next.  Try to get at least a
> half-wavelength of antenna (half) plus feedline at the lowest frequency
> for best efficiency, as high as you can in the air.
>
> > remote switching so as to be able to insert different matching stub
> > lengths
> > before transitioning to coax?
>
> Not necessary.
>
>  If you use underground conduit what
> > else
> > can/cannot go in the conduit with the ladder line?
>
> Have not tried this.  If I did, I would not run anything with the ladder
> line.  Would use seperate 4" PVC and do the best I could to keep water
> from getting into the conduit.   Perhaps dry air under pressure.
>
> >
> > Could you recommend a good reference book or other resource on using
> > ladder
> > lines?
>
> ARRL or E&E Handbooks prior to 1960, the older the better.  Only
> commercially produced true ladder line (dielectric being 95% air) I know
> of is from www.w7fg.com
>
>  73 es good luck,
> Mike, ac5p
>
> - - -
>
> Your moderator for this list is:
> Larry Wilson KE1HZ antennas-owner@mailman.qth.net
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