Well - here it is - 2008. Happy New Year to all Topbanders.
Last night - the band was pretty interesting - but I didn't make any QSOs.
I was able to hear a few signals from Europe - SM4CAN, G4AMT, PA0CQN and
EL2DX at his sunrise. I also heard RA4LW - well enough that he normally
would hear me - but he heard nothing.
I am hoping this is due to conditions and not a recent change I made to
my antenna system. Last night felt like one of those nights where the
wave angles were skewed and things were coming in from a high angle.
I have seen this happen where my beverages lose their directivity. Last
night, the beverages were somewhat confused - but even more so, my new
transmit antenna was totally baffled.
Before the Stew Perry contest - I strung up a wire about 80 feet away
from my gamma matched vertical - intended to give me some gain to Europe.
After getting it tuned and putting 24 radials under it - I saw about
1.3 db of gain - as measured by a field strength meter about 500 meters
away from the antenna. The wire was tuned for 1760 kHz and was acting
as a reflector.
I decided to move the wire element 1/4 wave away and try to phase the
two verticals. I had an old 80 meter Comtek 4 square box that had
most of the components I needed - and with some additions from my
junk box, I had a hybrid coupler for 160 meters (to use when in the
end fire position) and a unun impedance transformmer (for when using
the array broadside). I am seeing excellent results during the daytime
on local signals (N6TW/7 about 40 miles away to the south and an AM
radio station on 1670 kHz to the north). My local noises also seem
to suggest this array is working.
However, on most signals I could hear on the band last night, it almost
made no difference which direction I was pointing with the array as
signals were very constant.
Hopefully, conditions will be "better" tonight and I can feel better
about how this is working.
In the mean time, I believe that it is indeed possible to use a gamma
matched tower in a phased array. I know there is a concern that the
gamma will affect the phase relationship. However, thinking about this,
I believe that the current at the base of the tower has to obey what
the shield of the coax is trying to do - and all of the gamma "magic"
doesn't change that.
I also know K6SE was able to phase two gamma matched towers with good
results.
So - I would encourage those of you who might be able to try a phased
array - but haven't because one (or both) of your antennas are gamma
matched - to give it a try. The trick would be to use a hybrid coupler
and 1/4 wave lengths of feed line - which should force the current to
be in the right phase.
My second element is made of wire and strung from a taller tower. The
vertical section of wire is about 70 feet long and the top of the tee
is around 18 meters in length (maybe 19). It resonants around 1830
kHz. I did not notice much change in the resonant frequency when I
detune the gamma matched tower. I will make an accurate F/B reading
of this with my field strength meter later today.
If you hear me on the band - I would appreciate any signal reports
compared to the other signals on the band. I'll be the one sending
"1111 2222 3333" over and over. :-)
73 Tree N6TR/7
tree@kkn.net
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