I currently have a 2-wire "sloping"fan dipole for 75. The ends are held
with a 3' separator made from 1/2" PVC conduit.
End spreader @ 90 to 95 feet
http://www.rogerhalstead.com/ham_files/AntennaSpreader1.htm
Feed point and common mode choke.
http://www.rogerhalstead.com/ham_files/AntennaFeed2.htm
It covers about a third of 75 with both wire being the same length. I
plan on adding a third wire equally spaced so the ends will form a
triangle. The wires will also be of different lengths to get better
frequency coverage.
A 75 meter, sloping, fan dipole is definitely NOT a balanced antenna.
I'm building a new choke with 7 cores and 1/8th in spacing between the
cores. (Lexan spreaders) I had to add a second choke where the feed
line reaches the tower to keep RF out of the shack. With just the one
choke at the feed point, at about 1 KW out, all the LEDs in the shack
would light. Adding the second choke seemed to tame it as no LEDs light
at full power, and I can detect no RF in the shack.
When I had the antenna facing NE, I heard lots of stations in Europe the
first night it was up. A few nights later I started working them.
I've use the AV640 mounted on a 24' Al mast. On 40 meters I had very
good results. I had equally good results with a half wave, center fed,
sloping dipoles to the NE and NW. an a/B comparison would show one
better and a short time later the other would win. There were several
times at the last sunspot cycle low that 40 was open world wide for 24
hours at a time.
The problem here is a lot 200 X 200 doesn't give a lot of room for
multiple antennas with out interaction. I was amazed at how much the
sloping dipole over 50 feet away affected the AV640 on 40.
73
Roger (K8RI)
On 3/26/2015 3:12 PM, LY2KZ wrote:
Hello gentlemen,
I'm considering one antenna for domestic - continental contacts. I'm
curious about all pros and cons of this construction and possible
pitfalls. That is a fan dipole having three wires. Something like here
http://www.hamuniverse.com/multidipole.html One wire is for 7100kHz,
another for about 3800kHz and third for 3550kHz. My idea is to have
two bands covered in full. Is there anyone who has had experience with
fan dipoles? What should I keep in mind before starting to build? Yes,
tuning perhaps will not be very simple, but hopefully I will manage.
How far apart wires should be? 10in OK?
Should all center conductor legs go to the same side or vary left -
right - left
This will be low hanging antenna 10-15m. For DX contacts there will be
another antenna.
Thank you
Vytenis LY5T
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73
Roger (K8RI)
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