When I first moved into my 3rd floor (top floor) apartment 11 months ago,
I wanted to get back on HF ASAP. So, I rounded up all the wire I had and
made a 153'4" dipole with an SO-239 chassis mount at the feedpoint. I
strung the antenna around this red brick building and was on the air with
my FT-817 and LDG Z-11 tuner in no time. The antenna tuned easily even
down to 1.8 mhz but I was running a straight piece of rg-58 coax from the
feedpoint to the tuner and I was getting a lot of RF in the shack.

I posed this problem to this group and was told to coil several turns of
coax at the feedpoint. I looked around for a form and found a 2-3/4"
diameter
glue bottle. I wound 9 turns of the existing coax around this form, then
used
superglue to hold the turns together. Came out rather nice and worked very
well!

A few months later I was told I might get better results with more turns on
a
larger form. I grabbed another spare coax piece and this time used a CD
50 pack round case for a form (5-1/4" dia, 12 turns). This worked even
better!
In April I finally got permission to put an antenna or support no higher
than
10 feet high on the roof of this apartment building as long as I did no
permanent
changes. I used a Rat Shack vent pipe mount and 2 - 5 foot masts to hold up
the top of a Van Gorden 134' "All Bander" antenna. Nice landlord, eh?

With the All Bander in place and after several weeks of comparing
performance
of it with the old antenna, I took down the old antenna and wrapped it up
and
threw it in the closet. Now, I'm running a FT-857D and a LDG Z-100 tuner.

I thought I'd like to build a 6 meter SSB/CW inverted V dipole out of the
leftovers from the old antenna/coil/coax setup in the closet. No sweat but I
am
concerned if that a 2-3/4 inch, 9 turn choke would be ok on 50-51 mhz at
50w?

I'm too impatient to wait so I'm gonna start building now but I 'd very much
like to hear your opinions - I can always make changes and even build more
coax assemblies with coils wound on one end with different turn diameters
and more or less turns as I have several coax assemblies in the closet that
are'nt
getting used right now.

Anyone have an opinion for # of turns and what diameter would be best for
50w @ 50-51 mhz SSB/CW? BTW the antenna will be taped to a large
window on the 3rd floor, facing east & about 3-4' from my PC and radio gear.

73's de Ken KG0WX, Denver Area, Colorado.

On Sun, 4 Jul 2004 10:14:58 -0600, "Ken Bessler"
wrote:
Anyone have an opinion for # of turns and what diameter would be best for
50w @ 50-51 mhz SSB/CW? BTW the antenna will be taped to a large
window on the 3rd floor, facing east & about 3-4' from my PC and radio gear.

Hi Ken,

Simply think proportionality. What worked best at which band? Scale
by band. The choke is principally designed as an inductor. More Z,
better. However, as with anything in nature, there are capacitances
that come into play. For these chokes they aid in the sense of
offering a resonance that further increases Z. However, such
capacitances, at some frequencies, become series resonant
opportunities and the game is gone.

The standard advice for 6 to 8 turns of 6 to 8 inch diameter work well
for mid-to-upper-HF, smaller is indicated by the rule of proportions,
but not very much smaller. Using ferrites offers a more controlled
approach and becomes a matter of selecting the right material, visit:
http://bytemark.com/products/content0.htm
specifically (for discussion of materials and properties):
http://bytemark.com/products/content2.htm

73's
Richard Clark, KB7QHC