ALA1530LN and the tale of four NDB's

Useful information regarding antennas for SDR products.
Paul
Posts: 236
Joined: Fri Feb 17, 2017 9:52 am

ALA1530LN and the tale of four NDB's

Postby Paul » Tue Aug 14, 2018 3:49 pm

My "QTH" is about 130m up on a south facing hillside, in a rural location and the antenna is mounted about 5M from the house on an approx 2M mast, with an uninterrupted view to the S/SW.
Previously I used an active mini-whip (with, I think pretty fair success) to receive these beacons.
However, the Wellbrook rather put it in the shade, although I have only found one or two additional ones since I began using it.
I do not have a rotator as yet and have satisfied myslf with re-orientating it manually, occasionally and keeping the direction for several weeks befor changing it.
As a result, I have found one or two beacons sharing the same frequency, which is unsurprising. However, I am puzzled as the additional beacons found are turning up in the antenna's "side-lobes" and not in it's main field of "look."
With the loop open to about 185 Degrees, I am currently receiveing additional beacons to those previously identified on 100 and 85 degrees, whilst those that share these frequencies , located nearer to me and bearing 198 and 203 degrees are not currently audible, whereas they are normally loud and clear.
I appreciate that this is a "black art," but is there a simple explanation....please.

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g1hbe
Posts: 350
Joined: Sat Jan 17, 2015 3:28 pm
Location: Cheshire, UK

Re: ALA1530LN and the tale of four NDB's

Postby g1hbe » Tue Aug 14, 2018 6:52 pm

Me again, sorry.
Don't forget the main responses of the Wellbrook are 'off the edges', with a hole going through the centre of the loop.

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Andy

Paul
Posts: 236
Joined: Fri Feb 17, 2017 9:52 am

Re: ALA1530LN and the tale of four NDB's

Postby Paul » Wed Aug 15, 2018 12:03 pm

Thanks for you patience yet again Andy
I have owned up to being non-technical. However, please now add technically blind or worse.
Having "studied" the polar diagram, I totally misinterpreted it, assuming that the "deep nulls" of the figure of eight offered the lowest response, permitting one to null out the unwanted signals and that the "hole" provides the best area of look.
Now pretty impressed with the directionality!
A rotator now looks an awful lot more desirable (when I can get it past the "finance dept)."
What a plank!

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g1hbe
Posts: 350
Joined: Sat Jan 17, 2015 3:28 pm
Location: Cheshire, UK

Re: ALA1530LN and the tale of four NDB's

Postby g1hbe » Wed Aug 15, 2018 12:47 pm

I wouldn't worry about it, Paul. It is completely counter-intuitive that the loop should receive best when 'edge-on' to the source. Until you start to analyse what's going on with a loop, that is. Then you get one of those 'Ah!' moments and you never look back. Sounds like your Wellbrook is working as it should. I would never give mine up, it has literally saved my hobby with its noise-busting qualities. I have it mounted at gutter height on a cheap Maplin rotator which has somehow survived our Pennine gales for many years.

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Andy


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