The W7LPN version of the Inverted L Multi-Band 10-80m Antenna
(See latest update 03-30-09)
Fence Wire- I prefer electric fence wire for all my latest antenna
experiments. It has worked well for QPR
camping, outings, and emergency preparedness, as well as fixed base antennas. I keep a 50 meter
roll on a bolt with a rechargeable drill to
retrieve the antenna wire, and a cheap fishing pole, 10lb line with 1oz sinkers, in my camping bag. This is
all I've ever needed to throw a long wire
up in the trees. In this inverted L, limited space
was what was driving me,
so I used every inch of wire I could fit.
length of the antenna is about 100 ft. 70 feet to the bend, then
about 30' down at an angle to the pole extension. These dimensions
were used to add the maximum length of wire and stay within my
property lines. With the 70Ft straight wire alone, I could get 80m, but
not 40. I shortened cautiously, then I got 40m, but lost 80m.
When I added the vertical section, I got 80-10m and my little
autotuner will tune it all at full band widths.
4:1 Guanella Balun- http://www.n0ss.net/qrp_4-1_guanella-type_balun.pdf
This balun was simple to
build and works as written. I ran Heliax from my rig to the feed point, which is at the left of the picture,
above my metal roof about 5 feet mounted on
a used golf course flag pole. One end is run a short distance to the metal roof, the other end extends the full
length of my home & shed to a 35 ft
mast with a 5 ft fiberglass extension, then drops about 30 ft to
about 7 ft off the ground mounted to a
horizontal PVC extension from the shed
keeping the wire away from the metal building. I have a pulley at the tip
of the pole, polynylon rope, an insulator
and can easily lower the antenna when
needed or stormy weather. With the wire laying on a metal roof,
lighting strikes are of
Latest Update 03-30-09
After much on the air testing
It performed marginally on 75M and not very impressive on the higher bands, so I removed the balun at the feed point, threaded an SO-239 into my metal roof and feed it directly to the wire from there, leaving the flag pole in place to give elevation off the roof for a few feet.
The metal roof can now act more like a ground plane. I ran the transmitter to a manual home-brew roller inductor tuner, and the bi-pass switch goes thru the auto tuner. It auto tunes nicely on the higher bands with improved performance. I bi-passed the auto-tuner and use the manual for 75m with improved performance. If the connection at the SO-239 holds up it should work well for some time.
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