Hi Rob,
You ask some good questions and make some interesting observations.
Nope, it is the same radial system. I don't have a reasonable way
(time/money/effort) to create a whole new 50-60 wire buried radial system
for this experiment. I just disconnected the 43' vertical from the radial
mounting plate and connected the 100' vertical wire to the output of the
remote tuner. Simply replaced one radiator with the other.
The 100' tall wire's tree branch anchor is, at the apex, offset from the
center of the radial field by maybe 15'. So, being that it is wire, I just
angled it over and connected it. My figuring (probably bad) was that a 15'
horizontal run over a 100' drop isn't a very steep angle and I'd work with
what I had. I suspected that could be an issue when it just didn't play at
all. That is when I rigged up the elevated radials. Several links folks
have pointed me to describe the elevated radials and I thought I'd give
that a try instead to salvage the operation. Not a big deal since this is
really just a learning experience and even failure is learning.
At this point I can A/B antenna switch between the 43' using buried radials
and the 100' using the elevated radials.
The elevated radials don't meet your design criteria either. Only three of
them at roughtly equal spacing around the compass. I cut them at 135' long.
They aren't perfectly parallel to the earth's surface due to support points
being at uneven heights. They certainly aren't at 20' from the ground. The
wire is insulated but they are just tied off to supports at the ends.
All in all a complete mess of efficiency. Throwing up something temporary
in the winter rain/cold has some limitations that aren't conducive to good
160m operation, it appears. :-)
I did operate in the Stew Perry last night using both antennas to transmit
and the BOG to receive. The BOG worked better than I expected, notice I
didn't say "great". The 100' performed poorly compared to the 43' using
CONUS distances as a benchmark. No EU or JAs heard at my QTH...
I think I'll pull the 100' wire and supporting stuff down. It doesn't seem
worth the trouble since it isn't providing any additional benefit. Nothing
is easy at 160m. :-) But it has been fun.
Thanks for the insight.
73,
Todd - NR7RR
>Hmmm....you DID relocate or rebuild your ground system so it converges
>on a point below the bottom of the 100 foot tall wire right? I mean,
>you aren't using the 43 foot vert. ground system with the 100' wire?
>A series fed vertical isn't rocket science so let's not over think
>this. If it doesn't work well it is probably inefficient. I'd make
>sure your ground system is adequate. No, you can't use an existing
>ground system that converges on a point 30 or 40 feet away from the
>100' wire. Yes, I've had people ask me if they can do that, so it is
>worth mentioning.
>You can go the elevated route, but it is _critical_ that it be
>constructed correctly to adequately replace a full ground system at or
>below grade. You need four radials parallel to earth extending out
>90 degrees from each other and their lengths must be equal and 90
>degrees long (1/4 w.) at frequency. The ends must be h.v. insulated.
>They should be elevated 20 feet on 160 m. to completely de-couple from
>earth.
>73
>Rob
>K5UJ
_________________
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
|