Bill Fisher - W4AN writes:
>I got a great private note from NA8V (Greg) regarding antennas and
>heights. Greg sited some observations with various antennas and heights
>on 10M and 20M. It was very interesting and I hope he will post it to
>the list.
So where is it?
>These real world observations are exactly what I would like to see more
>of from this list. There are quite a few of you who have A LOT of
>antennas at different heights. How about passing on some observations?
Ok - here goes.
As I have said before - I was very luckly to get to spend
about 12 years operating from N5AU's station. Besides
getting to use some big antennas - I got to operate with and
learn from some great operators. I also learned alot about
station design and how to do antenna work.
Over the years the station changed - as we fine tuned the setup.
I think the first time I ever saw N5AU there were about 26
towers and at one point we had it down to about 18 - I think the
final tower count for HF came in at 20 or 21.
This time I will discuss what I saw on 15m - I did most
of my operating in the DX contests on 15m and thus know
that band better than the rest.
BTW - the terrain around the N5AU station was mostly
all the same elevation except towards the west where it slowly
dropped off. Gently rolling terrian. AU was a bit higher than
the stuff around - nothing special.
On 15m we had the following:
5 element Telrex on 32' boom @ 175' - Rotary
This was a great antenna - it was the best for when
the band was dead, Long path and over the pole QSOs.
For the most part we kept this one pointed north
for the deep over the pole contacts. It was also
good for working K4VX at 1am at the bottom of the cycle.
5 element Telrex on 32' boom @ 60' - Rotary
This was the other antenna that turned on this band
and in the multi-multis this antenna was given to
the mult station. This antenna was on the east
side of the lot and had a clean shot to Africa.
There were very few pileups that could not be broken
with this antenna. 60'-70' is a great all around height.
I usually used this antenna pointed west ("T-connected to the EU
stack) in the sweepstakes contest. When doing a single band
I would point this antenna on Africa most of the time.
5/5 element Telrex on 32' booms @ 135' over 90' fixed on Europe.
This was a great antenna for europe - there were times when we would
be running europe that locals could not hear. It was hardwired
in phase so that there would be no relays to fail. K5ZD selected
these heights - when this tower/antenna was first installed
Randy put up 3 antennas at 45'/90'/135' - he built up a relay
system that would allow use to use any single antenna - the top
pair or the bottom pair. There was no way to run all three
at one time - had there been we might have never taken the lower
one away. In any event - the top pair was almost never worse
than the lower pair or any single antenna - so we kept just the
upper two and took the low one and used it for the antenna at 175'.
I do recall short perids of time that the low antenna alone (45')
was the best antenna to england at the peak of the cycle - but never
for very long or very often.
4/4 cushcraft yagis 90' over 45' - fixed on South America
The history fo this is that we had a single 4 ele cushcraft
on 10m fixed on SA and it just was not enough - we had to keep
turning some othe big antenna down that way to break a pileup
so we stacked a pair and fixed that. It worked so well on
10m that we just did it again on 15m. This antenna worked well and
almost never gave us a reason to turn either of the rotary antennas
to the south. We did do some rediminsions to the stock antenna.
4 element cushcraft (stock) at arond 120' - fixed on the South Pacific
This antenna was added by me - when we would do M/M the I only
had the high rotary as the low rotary was given to the mult station.
I usually had the high antenna either north or later in the day
pointed at Africa. This I would have to turn the high antenna
from east out to the southwest in order to pick up the
odd pacific stations that would start calling in at 18z. The
height was chosen - because this was above the south american
stack and below the high antenna. In other words where it would
fit. This antenna really helped work the pacific stations
when the other antennas were elsewhere.
5 by 5 element Telrex 32' boom 70' high 70' apart - fixed on Japan.
This was the BEST antenna for Japan 95% of the time. If the
band was open to JA then this antenna was the one that worked.
It had a great pattern and new ops (me) had to learn to
transmit on other antennas every so often or you would
switch over to work some south american and discover that
there was a strong W8 on your frequency. Japan is
on a heading of about 315 from Dallas and this antenna was
not good for working W6 a heading of 300 degrees.
The only time this antennas was not the best for JA was
when the band was just opening or closing - then the 175'
footer was better. According to the N6BV arrival angle
data the path to JA occurs at 9 to 10 degrees for about 90%
of the time the band is open. 60' to 70' foot high
antennas over flat ground have their peak gain at about 10 degrees.
All of these antennas came into a 6 positon dowkey relay.
I modified the switch box to allow the operator to
switch in any two of the antennas at a time. This proved
to be the way to go - and we would almost always be CQing
in two diffrent directions. I think this is very important.
Taking what I learned from using all of this - I designed
the W5KFT station on 15m to have three 5 element hy-gain
155CA antennas at 135'/90'/45'. The two lower antennas
are fixed on europe and the top one rotates. I feed the
towo lower ones in phase all the time and then just do
simple upper/lower/both switching between the low pair
and the top antenna. The allows for multi direction
and all antennas towards europe. We are adding some other
antennas on another tower for japan.
If this is sorta what Bill was looking for - I will do
some of the other bands too.
73.
--
George Fremin III
Austin, Texas C.K.U. "It is hard to be in one place at the same time."
K5TR -- Overheard at the TR-Log booth
512/416-7010 at the Dayton Hamvention
geoiii@bga.com
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