In article . 196,
"Ed_G" wrote:

Our ARES group plans on installing an Inverted V antenna on the
second story flat roof edge of a local building. The antenna mast is 13
feet tall above the roof edge. The Inverted V will run parallel the edge
of the roof and be approximately 35 - 40 feet per leg. Our primary
operations will be 80/75/40M with a desired ability on 60M. The
building custodian/owner will not tolerate open wire feedline with its
associated standoffs due to aesthetic considerations, so we must feed
this antenna with coax fastened to the mast. At the base of the mast,
on the roof, we will be using an SGC-237 antenna coupler.

The above setup is a given, with no room for compromise.

My questions for this group are as follows:

Would we be better feeding the above antenna feedpoint with twin coax
runs, using the center conductors as a 'balanced' feedline, or would we
be better of using a single coax to the feedline? In either case, the
coax runs will not exceed 20 feet and we must accept the losses in them.
Email response from SGC seems to indicate we would be better off with a
single feedline, but I am dubious about the SGC Tech Rep's response
since he/she does not seem concerned about feedline radiation.

Also, what recomendations do you guys have for use of a balun? I
believe, at the least, we would need a 1:1 balun at the Input of the SGC
coupler so as to keep RF from getting back down the shield and into the
building. SGC response seems to indiate they don't think a balun is
necessary anywhere, which is another reason I am not thrilled with
their response.

Comments?


Ed K7AAT

hi Ed

you might try using a plastic mast (pvc or fiberglass) with enought
strength to survive the load and weather thats hollow and try running
laddar line inside

you can use some solid plastic pipe some ham places sell it or
even a short piece ofmetal mast if you can cut a small slot in
the plastic such that it's integraity is good or u can run the
laddar line down the outside of the plastic pipe pprobably easist
and paint it all black w/rf ok paint very hard to see the feed line
then


way back when i spoke to somone that was 'smart' at sgc and they said
using a short piece of laddar line to feed the dipole (as they way i
happened to do mine almost exactly as you described) they said it was
less than ideal but not bad as long as the laddar line was i believe
less than 10??ft long they said the output definately shouldn't
have any balun as far as the coax feeding the tuner?? most
seemed to agree it wasn't needed but i thru one in anyway both on
the roof and in my shack


my set up thou slightly different than yours unscientifically seems to
work very well, i don't have nasty stuff on my coax run to the tuner
my swr even w/a very short dipole is nearly almost always max at 1.2
worst case the tuner tunes in seconds and i've enjoyed some pretty
good fun the total length of my dipole is maybe less than 40ft

is my set up ideal? or good as a beam? i'd guess not but i had co
op board roof constraints as you sorta have so it's best effort
and i've had a blast with it from 160 to 6m


i got a bunch of my ideas for it's actual design and final construction
from my fooling aournd , here in this group , sgc personal I think i
spoke to the original owner once, there manuals and googling


goodluck Ed