Several posts were made earlier concerning running a 160M inverted "L" or
"T" up the side of an 80/40 vertical. I recently re-located a 160M "L"
from a TV tower adjacent to the house where it had worked somewhat to the
"back 40" where my vertical resides.
I elected to house the matching circuits for all 3 bands inside one
enclosure and to switch the 50 ohm feeds with relays. Before starting, the
natural resonance point of the vertical (53 feet high with an 8 ft top hat)
was 3270 khz. After running the 160M L up the side, the natural resonance
dropped to 2880 khz. I had to change both 80 and 40 matching circuits as a
result. Part of this change may have resulted from placing all the matching
circuits inside one box.
Here is the final configuration of my 160M "L":
Vertical height: 51 feet
Spacing from 80/40 vertical: 24 inches (using PVC pipe as standoffs-no
problem at 600 watts)
Matching: 14 turns #10, 3" diameter, 3 turns per inch, tapped 3 turns from
the top, lower end grounded.
Horizontal wire approx. 73 feet in length.
The antenna has less than 2:1 SWR from 1800-1878 khz.
Radial system consists of 30, various lengths, 35 to 70 feet. I am adding 4
more wires about 125 feet in length once the vegetation stops growing for
the year.
At my location 160M has not been very active this summer. I worked 5K0Z
earlier with a good report, and last night SV8ZS with a 569. As these were
made running 100 watts, I think the antenna is going to play. Performance
on 80 and 40 have not been affected....the antenna still works well on those
bands.
The only problem I can see for my installation is that the horizontal wire
runs west and can be expected to make the radiation pattern somewhat
directional. I would like to change the "L" to a "T" in the future to see
what difference this makes.
Bill, VE3NH/VE3CSK
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