From: "steve d" <kc8qvo@yahoo.com>
To: <topband@contesting.com>
Sent: Thursday, January 12, 2006 5:57 AM
Subject: Topband: K9AY loop still not working right,everything checked out OK
though
>>Steve,
>>Are you seeing and front-to-back on signals when you
>>switch directions? That s the first thing you should
>>look for.
>>
>>Mike, W4EF.................................
>Mike, I am able to "turn off" most stations that I hear, only
>ones that are real strong I cant get to go away. So I would
>say that yes, I am seeing front-to-back. I probably do not
>have the antenna tuned correctly though, but I am not so
>sure that has anything to do with the level of noise that I
>am picking up.
>
>Steve, KC8QVO
Steve,
The fact that you can make stations "go away" by switching
direction suggests to me that your K9AY loop has a decent
pattern. If it was strongly coupling into nearby objects, I would
expect that it wouldn't have much in the way of front-to-back,
although as I recall from computer modeling a tower next to a
K9AY loop, you can get into a situation where you have good
front-to-back when firing away from the tower, but no front-to-
back when firing towards it. In that case you might get a signal
to-noise improvement when listening away from the tower, but
when firing towards the tower, you would get no signal-to-noise
ratio improvement. The way to test for this is to listen for stations
coming from different directions to see if the array has decent
front-to-back in all four directions. In other words, if your listening
to a station coming from the east, do you get the same
front-to-back rejection when you switch from beaming east to
the west as you do when listening to a station from the the
north when you switch from beaming north to the beaming
south, etc. If the array only exhibits front-to-back on stations
coming from one particular direction instead of all four principle
directions, then that suggests that you have a coupling
problem which could explain the arrays lack of noise rejection.
How far away is your TX antenna?
73, Mike W4EF............................................................
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