ALA1530LN and the tale of four NDB's

Useful information regarding antennas for SDR products.
Paul
Posts: 274
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: 410
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: 274
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: 410
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

Patrick73
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Joined: Thu May 31, 2018 9:39 am

Re: ALA1530LN and the tale of four NDB's

Postby Patrick73 » Tue Nov 20, 2018 7:30 pm

Glad to notice there are some NDB chasers here !
This is one of my favourite aspects of the hobby despite digging out new ones is really tough now due to the increasing noise level and the number of NDB already logged (2024 from 93 countries).

I also use an ALA1530LN, mounted on the balcony railing (no garden, no backyard).

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Murphyv310
Posts: 9
Joined: Mon Aug 13, 2018 8:55 pm

Re: ALA1530LN and the tale of four NDB's

Postby Murphyv310 » Fri Dec 21, 2018 11:06 am

Hi.
I've used an ALA1530 for some time. There is a weakness though and that is where the loop enters the amplifier, under the outer alloy "loop skin" there is ferrite and in strong winds this can crack and make the loop defective. A new amplifier assembly can be bought from Wellbrook for around £100 which is excessive for a design issue. I advise using a strong and stiff plastic tube and attach it to the uppermost part of the loop secure the other end securely to the amp to stiffen the whole assembly up and reduce stress from the loop to the amp especially in high winds.

Wellbrook's amp is actually just made on Veroboard which is lossy, I rebuilt mine with two transistors and a waterproof box, the loop now works better than ever. There is more info here for anyone that is interested. https://www.george-smart.co.uk/projects/wellgood_loop/
Last edited by Murphyv310 on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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Cheers Trevor :D

g1hbe
Posts: 410
Joined: Sat Jan 17, 2015 3:28 pm
Location: Cheshire, UK

Re: ALA1530LN and the tale of four NDB's

Postby g1hbe » Fri Dec 21, 2018 1:41 pm

Murphy - the supporting of the upper part of the loop is exactly what I did with my installation. I really didn't like the idea of the loop wagging about in the wind, as all the strain would be going through the mounting points in the amplifier box.
Re your own loop, I did a similar trick for VLF use. The simple two transistor design (the one that pops up everywhere on the net) was used but I replaced the standard output ferrite with a 73 type ferrite to extend the LF response and installed a LPF which gets rid of everything above 100 kHz.
This works well in the sub 50 kHz region where the Wellbrook begins to fall off, and now I can hear the 17.2 kHz SAQ transmissions at good strength.
The loop element itself is a plastic hula-hoop with four turns of wire. I think I broadly tuned the loop with a fairly large capacitor to 'hump' the tuning up a little at the low end. It was all a bit 'suck it and see' but it works well.
Merry Christmas.

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Andy

Murphyv310
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Joined: Mon Aug 13, 2018 8:55 pm

Re: ALA1530LN and the tale of four NDB's

Postby Murphyv310 » Fri Dec 21, 2018 7:04 pm

Hi Andy.
Sounds like a good mod.
I'm more into Long and Medium Wave DX plus air band which I use a different aerial. I occasionally listen to other stuff and I've found the modded Wellbrook is good up to 100Mhz which is handy for me.
I'm now constructing a 1.2meter loop using 15mm copper tube and two Chinese LNA amps in a balanced configuration. Once its done in the new year I'll post up the details here.
I also play about with good quality Valve comms sets and a new addition a XHDATA D-808, a great little portable.
Have a great Christmas too :D

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Cheers Trevor :D

g1hbe
Posts: 410
Joined: Sat Jan 17, 2015 3:28 pm
Location: Cheshire, UK

Re: ALA1530LN and the tale of four NDB's

Postby g1hbe » Sat Dec 22, 2018 12:00 pm

I like the pair of Chinese amps idea. Are you a regular visitor to the Vintage Radio forum? If you are, I guess your username refers to those superb Murphy sets with the wrap-round ply case and the control flap on top? I loved those sets, they seemed capable of producing the best 405-line pictures I've ever seen - needle-sharp focus, a lovely grey scale, lots of detail and yet the line structure was well hidden. We had a few out on rent in the late 60's/early 70's and I don't recall much trouble. Oops, drifting OT (again...).

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Andy

Murphyv310
Posts: 9
Joined: Mon Aug 13, 2018 8:55 pm

Re: ALA1530LN and the tale of four NDB's

Postby Murphyv310 » Sat Dec 22, 2018 1:03 pm

Hi Andy.
You'll see me on the Golbourne vintage Radio forum. VRAT as well. I used to be on the United Kingdom Vintage Radio forum too but had a big fall out and was kicked off. I do have many Murphy sets from the V310 V410 V320 etcetera, I've limited space and a good few items have been donated to a local Radio & TV museum run by a friend in Sorn Ayrshire.
Some of my collection is here https://www.radiomuseum.org/collection/ ... nough.html
Again sorry to go off topic

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Cheers Trevor :D


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