Topband: K9AY Loop Proximity to Structures

[Kees Nijdam]

Pete,

The end of my 160 meter tx antenna, an inverted L, was only 7 meters away from the top of the K9AY.
It was absolutely necessary to detune the inverted L during listening on the K9AY. I did it by switching it off (floating) with a fast vacuum relay at the feed point.  Without detuning the TX antenna, the K9AY was  omniderectional, all nuls gone.

73, Kees


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Van: Mike Furrey
Verzonden: zondag 24 januari 2021 18:28
Aan: Tim Shoppa; N4ZR; topBand List; Kees Nijdam
Onderwerp: Re: Topband: K9AY Loop Proximity to Structures

 I had  the K9AY loop in my back yard at my old QTH in Spring, TX. I quickly learned to orient the loop for noise reduction (had a noisy strip shopping center about a half mile due east) rather than signal strength. The North loop aimed through the house (about 20' from the house) but I could still hear Europe better on the loop than the 160 inverted L. Just my observations.

73, Mike WA5POK
    On Sunday, January 24, 2021, 11:46:44 AM EST, Kees Nijdam <clnijdam at knid.nl> wrote:  
 
 Pete, in my previous QTH the pole of the K9AY was in the corner of my house, both loops partly running alongside the walls.
I had good nuls in all four directions and Iworked 230 dxcc on topband.

Kees, PE5T

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Van: Tim Shoppa
Verzonden: zondag 24 januari 2021 16:53
Aan: N4ZR; topBand List
Onderwerp: Re: Topband: K9AY Loop Proximity to Structures

Pete, I live in a residential neighborhood (not the most dense by any
means), and all my receive antennas will point towards my house or a nearby
neighbor's house.

There are certainly buzzes and whines in parts of 160M that are accentuated
in some directions on some RX antennas and not so much in other directions
and other antennas. Presumably these are a wide spectrum of consumer
electronic devices. But (other than my daughter's horrible RFI producing
LED strip power supply which has been banished, replaced by a linear
supply) I can't say any one direction or antenna is overall worse than any
other direction.

When I'm picking a run frequency I tend to stay away from the worst of the
buzzes and whines. The buzzes and whines wander and turn on and off. So
sometimes what was a good run frequency is not so good later in the night.
After midnight I think folks turn off their TV's and computers and I can
tell the buzzes and whines bother me less.

If you are worried about the directivity of the K9AY being affected by
nearby structures, you might carefully listen to stations in various
directions and figure out where the nulls are for each loop/direction. The
null on a K9AY loop is very pronounced (unlike the forward directionality
which is very broad). I see no indication that my house (which is less than
40 feet away from the K9AY I use most often) and the neighborhood chain
line fences (which are less than 30 feet away from the K9AY) affects the
null direction.

Tim N3QE

On Sun, Jan 24, 2021 at 9:29 AM N4ZR <n4zr at comcast.net> wrote:

> When I put up my K9AY loop, it was convenient to do so at a location in
> my back yard where I already had a stub of tubing (from a defunct
> birdhouse) protruding above ground.  I didn't think about it before
> this, but that puts the northeast lobe to Europe going through my house
> at a distance of much less that 1/4 wavelength on 160. The house itself
> is pretty RF-quiet, and the antenna seems to work (using it to select
> one of two broadcast stations on the same frequency) but I'm wondering
> if it would be worth the effort to move it to a location where it has a
> clear shot to Europe
>
> --
> 73, Pete N4ZR
> Check out the new Reverse Beacon Network
> web server at <http://beta.reversebeacon.net>.
> For spots, please use your favorite
> "retail" DX cluster.
>
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