The K index crept up and prevented any kind of European opening - either
last night or this morning. Had RU3DX and RA4LW and SP6HEQ listening for
me around sunrise - but no signals were heard.
I did manage to replace the gamma matched tower with a second wire element
yesterday. This required the gamma tower to be detuned - using the W8JI
method that is explained in "The bible" (ON4UN book) or you can also see
it here:
http://www.w8ji.com/detuning_towers.htm
I made my second element the same dimensions as my first one. For those
who are interested - I just went out and measured one of the elements
and here are the dimensions:
Vertical portion of wire - 67 feet.
Top hat - 67 feet with the vertical wire in the center. That's 20.5 meters
for those of you on the metric system.
They seem to come out around 1830 khz. However, my second element has
worse SWR at resonance - I believe due to the gamma matched tower being
very close to it.
Even with a bad match in the broadside position (both verticals tied
together and using a unun to convert 22.5 ohms to 50) - I was able to
work J5C last night. The directivity seems as good - or better - than
the setup with the gamma tower with the added 30 degree line.
So - if I can make the matching better - I will probably stick with the
wire element. If not, I will likely return to the gamma matched element
and the delay line.
You can see the towers here:
http://maps.live.com/default.aspx?v=2&cp=rk23744szmwy&style=o&lvl=2&tilt=-90&dir=0&alt=-1000&scene=5591280&encType=1
The gamma matched tower is the one in the middle of the 4 square. The
first wire element is strung between the tall tower with the 3 element
40 on it and the VHF tower in the left side of the picture. The feed
point is near that green spot in the grass. This view is looking towards
the west.
Hopefully, this information is useful for those who might be thinking of
trying something similar.
Tree
PS: I was asked how I measured the phase delay of the gamma tower. I used
a RX loop antenna that was about 600 feet away from the array - broadside
so that both elements were the same distance away. I then sync'd a scope
off of my transmitter and compared the phase difference when only driving
one of the antennas (with the other disabled). I found the gamma tower
had a 30 degree delay compared to the wire element.
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