Jim.....You hit on a good point with a 1/4 sloper that it should be some
distance, in your case 5 feet, from the tower at the top or high voltage
end. Having the top right at the tower seems to deteriorate the
performance overall as many who have tried this seem to underscore.
What you have presumably are two verticals with an a periodic reflector
which is your tower. Having switchable gain both on RX and TX and some
F/B is great. I am glad you confirmed this with both NEC and on the air
tests.
Regards,
Herb Schoenbohm, KV4FZ
On 3/8/2014 2:38 PM, Jim Brown wrote:
On 3/8/2014 9:08 AM, Herb Schoenbohm wrote:
IMHO a wire 1/4 wave length long wire should preferably be
electrically connected to the tower and fed from the bottom of the
slope against a good ground system.
Herb,
That depends on the height of the tower. I have two sloping wires on
opposite sides of my 110 ft tower (with SteppIR and 2M long Yagi on
top) that are INSULATED from the tower and each fed from the bottom
against four radials elevated about 20 ft. The tower is grounded and
has a dozen or so quarter wave radials. The wires are held 5 ft away
from the tower at the top by a 10 ft section of 4-in PVC conduit. One
faces to 70 degrees, the other to 270 degrees. NEC predicts the same
gain of 2-3 dB with F/B of about 6 dB, and that's about the way they
hear. I feed one or the other, with a stub in the shack that opens the
feed of the antenna not being driven.
73, Jim K9YC
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