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Hi Pat

I think that some of the early ALA1530's had the amplification split between
the head and the antenna splitter. In the later units all of the
amplification was put at the loop. Was there any amplification in the splitter box of the
antenna which you opened up?

Thanks and 73

John


In a message dated 3/10/07 1:21:05 PM Central Standard Time,
preynaert@... writes:

Hi Dominique,

It wasn't even mine antenna; I got a broken ALA from a friend.

Pat.

"D.Kremp" <dominique.kremp@...> wrote: Hi Pat,

Hope you did'nt do that especially for us !

Tell us what happened to your antenna !

See you

Dominique

_____

De : loopantennas@... [mailto:loopantennas@...] De
la part de Patrick Reynaert
Envoyé : samedi 10 mars 2007 18:31
? : loopantennas@...
Objet : RE: [loopantennas] Re: Active loop antenna

Hi Dominique,

I've placed some pictures of an opened ALA1530 on the photo section of this
group page. After two days carefull work, I finally got to the circuit.

Pat.

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Good joke Nigel.
For a moment there I was thinking that you were a complete lunatic :-D

gregW:-)



====================================================================

--- In loopantennas@..., gandalfg8@... wrote:

OH DEAR

It was a JOKE, or my daft explanation was anyway.

Probably a silly joke, but one I thought so obvious that I didn't

even think

it warranted a smiley.

Apologies all, I sometimes forget that not everyone can tell the
difference:-)

regards

Nigel
GM8PZR

If the Wellbrook had the microprocessor function to determine the reception frequency to tune, the Wellbrook should not function with a receiver without any preselection. It could not function either with a signal splitter, that sends the signal to two receivers, each tuned to a deifferent frequency.

Cor Beijersbergen van Henegouwen

Potting electronics in wax or resin will only stop amateurs like us from copying the design. For industrial copiers there is no problem, when you invest in 2 or 3 antennas and are prepared to cut to them to pieces, or to treat them chemically you will be able to discover the circuitry. I have been working in the R&D departments in the consumer electronics business. It was quite standard even to look inside IC's of competitors, just to discover the technology and circuitry used.
But if the chinese or anyone else would copy the Wellbrook and sell it for a lower price, how many would they sell worldwide?

Cor Beijersbergen van Henegouwen

In a message dated 09/03/2007 20:11:07 GMT Standard Time,
toms_email_2004@... writes:
I am very frustrated at this point and I cannot think of what else to
try with my limited test equipment (multimeter & receiver). Does
anyone have any suggestions for things that I might try to determine
the source of my problem? I would appreciate any advice that people
may have regarding my issue.

----------------------------------------

Hi Tom

I haven't seen any other answers to your question but if I'm missing any
posts and repeating any other advice then apologies for that.
Apologies in advance too if it seems like I'm stating the obvious:-)

Without too much test gear my suggestion would be to take a step backwards
and eliminate some of the variables.

If you can get hold of a variable capacitor, say maximum of 350 to 500 pF,
you'd probably be better off testing your loop with that first so you're not
trying to test the loop and varactor circuit at the same time.
Your test technique seems fine, to me anyway, so I'd carry on in the same
fashion but with just the loop and capacitor to start, it's going to have to
resonate somewhere.
Alternatively, just a fixed capacitor in the range of, say, 100 to 500pf,
should give a resonance that you should be able to find on your receiver.
If not then you need to take a very fundamental look at your loop, is there
any nicked insulation, shorted turn etc, but I suspect you'll find a tuning
point and can then look more closely at your varactor circuit.

Again, I would suggest stepping back slightly.
Work with just one varactor to start, finding a tuning range for that will
confirm all is basically working, and go on from there.

Sometimes, jumping straight in works fine but if things go wrong you can end
up with too many possibilities for problems and that can make faultfinding
much more difficult, regardless of what test gear you might have.

regards

Nigel
GM8PZR

In a message dated 11/03/2007 11:38:50 GMT Standard Time,
onegammyleg@... writes:
Good joke Nigel.
For a moment there I was thinking that you were a complete lunatic :-D

---------------------------------

Cheers Greg

And you think now I'm not? :-)

regards

Nigel
GM8PZR

In a message dated 10/03/2007 16:12:04 GMT Standard Time,
mcqueen_34@... writes:
MICROPROCESSOR??????

1. The Wellbrook is NOT a tuned loop.
2. How does the loop know what frquency the radio is
tuned to...ESP?

--- gandalfg8@... wrote:

In a message dated 10/03/2007 08:45:02 GMT Standard
Time,
c.beijersbergen@... writes:

And BTW, what should the microprocessor be doing in
there?



--------------------------------------

It's used for the automatic tuning.

In order to cover the wide bandwidth the antenna has
to be electronically
tuned to the correct operating frequency and this is
done by rapidly sweeping
the tuning across the whole band and monitoring for
the point at which energy
absorbed by the radio is greatest as this will
correspond to the tuned
frequency of the radio.

SNIP
----------------------------------

OH DEAR

It was a JOKE, or my daft explanation was anyway.

Probably a silly joke, but one I thought so obvious that I didn't even think
it warranted a smiley.

Apologies all, I sometimes forget that not everyone can tell the
difference:-)

regards

Nigel
GM8PZR

In a message dated 11/03/2007 07:11:50 GMT Standard Time,
mpetrakis@... writes:

)We always forget that the characteristic impedance of an antenna is
actually the _radiation resistance_. What most people don't know is
when we match the radiation resistance of areceiving antenna with the rest
system, the antenna *transmits* half of the received energy. Check
_
() (near
the bottom of the page, it has
--------------------------------------------

That sounds a bit like pseudo science based on the maximum power transfer
theorem, whereby it can be shown that the maximum power transfer from any
source occurs when the impedance of the source matches the impedance of the
"receiver".
For a conjugate match the inductive and capacitive reactances, equal and
opposite, cancel and the resulting impedances are purely resistive and also
equal.
I've seen debate before on what happens to the "extra" energy but in
practice half is dissipated in the source resistance and half in the receiver.
It matters not whether you consider it to be retransmitted or just not
available in the first place, conservation of energy dictates there's no more at
the end of the process than at the beginning.

regards

Nigel
GM8PZR

Hi,

I would like to find some antique loop photos...
Here a photo from a french book. This kind of furniture is still found in the French Cantal region, but dealers mostly dump them, they do not know what it served for ....




Marc

--
--
Shortwave transmissions in English, Francais, Nederlands, Deutsch, Suid-Afrikaans, Chinese, Dansk, Urdu, Cantonese, Greek, Spanish, Portuguese, ...
Updated every 2-3 months.

In a message dated 11/03/2007 06:55:55 GMT Standard Time,
marcsje@... writes:

I would like to find some antique loop photos...
Here a photo from a french book. This kind of furniture is still found
in the French Cantal region, but dealers mostly dump them, they do not
know what it served for ....

_
()



Hi Marc

Interesting article, my French isn't good but I could understand better than
I expected after 45 years:-)

I can't point you anywhere specific right now but certainly I've come across
photos on the internet from time to time, google should help, and they often
appear in books on radio history.
Most of my books are in storage so can't help you much there either
unfortunately.

The front cover photo on one the magazines I have from the 1930s shows a
portable radio setup in a rowing boat.
Our hero is rowing his lady across the lake, presumably to the sounds of
sweet music, whilst between them in the boat sits a radio in a fairly large box,
a bank of batteries, a horn loudspeaker, and a loop aerial:-)

The early loops themselves were untuned, at least inasmuch that any tuning
capacitor was contained in the set itself rather than at the antenna, and
would be less usable as they stand with more modern receivers.
Although the article comments that the technology was in use for 30 years
before being replaced by ferrite rods, for most of that time the antenna was
housed in the set as a "frame aerial" so the old loops disappeared much sooner
than that.

regards

Nigel
GM8PZR

All right, folks!
If you really are so interested to study one man's product and imitate it, why don't you go and xray it? It just might be a waste of your precious time....
Seems to me, that it could be one of the best ways to make a pirate copy of the item....
Of course, I am very much interested, too, to make the best out of my hobby, but let the Chinese publish their own version of a Directive Active Loop, probably the Next Generation of "ALA", a much better one ever. It need not bee a clone, because they have a lot of designing skills of their own. Did you think, that they didn't?
I did ask for one from Tao Qu, my Shenzhen Guangdong friend for over a year ago. Let us be patient! It will be here soon.
If you like to hasten him, why don't you just call him?
86-13902977082, Tao Qu.
He's been in the US a few times, so he can speak rather well the American language, too.

By the way, you must realize, that in the Bei Jing (former Peking) University there are only geniuses, over 30 000 of them... They are going to overcome us very soon... They already have their own space program going fast! Tremble, oh people! (Hi!)
Ami.

"Greg W:-)" <onegammyleg@...> wrote:
Hi Pat

Thanks for the pic's.... BUT

It's built on perfboard !! ..that would have to be the most
unprofessional thing that I have ever seen in a commercial product.

And using perfboard is slow ,,if they had of used an etched board
assembly would be a LOT faster with less chance of construction failures.
This offsets the costs of a small etched board easily.

I thought Welbrook was much better than that ,,it really is backyard
standards of construction.

I think THAT is why they glue it all together , so you don't see their
work.

gregW:-)


=====================================================================

--- In loopantennas@..., Patrick Reynaert <preynaert@...>
wrote:

Hi Dominique,

I've placed some pictures of an opened ALA1530 on the photo section

of this group page. After two days carefull work, I finally got to the
circuit.

Pat.

---------------------------------
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always stay connected to friends.

yazoo_63 wrote: What kind of radio are you trying to receive them on? ... or maybe you're located in a valley surrounded by hills (or mountains ?).Barry

N4IJN

Yes, Many hills between us. It's not as good as you might think. We don't need BPL out here. The power lines leak enough on there own.

This is every radio. Battery powered and mains powered. Even at night.

Hello,

1)A loop is an inductor so impedance (complex number) equals j by
omega by L ??? (the dominant factor of the total impedance since an
actual loop has ohmic resistance and capacitance). The nominal
impedance you are referring is something a little different (see (3)).

2)After all you actually _tune_ i.e. resonate the system with a
variable capacitor (I guess you are talking about a tuned loop
antenna). So in practice you don't need that value.

3)We always forget that the characteristic impedance of an antenna is
actually the _radiation resistance_. What most people don't know is
when we match the radiation resistance of areceiving antenna with the rest
system, the antenna *transmits* half of the received energy. Check
(near
the bottom of the page, it has
math but makes clear in plaintext many, many, many misconceptions... I
remember a
series of posts here or at Shortwave-SWL-Antenna Group about
receiving antenna impedance. The link above answers many questions....)

(ducks to avoid flames)

Manolis

Hi Al,
By the way, all mail direct to you has been bouncing as of last evening. Your ISP rejects anything I try to send to you.
Steve

Hi Al,
Using very approximate input values to Reg Edward's "rjeloop3" program, gives 6000 ohms for the tuned loop, at 200 kHz.

73,
Steve

Is there a nominal impedance or approximate impedance for a loop
antenna? For example, a dipole is considered 72-ohm, a bevarage 450-
ohm. What is a nominal loops Z?

I have a 4-1/2 foot diameter loop antenna with 12 turns paralled by a
capacitor for the antenna and one additional turn for the pickup coil.
The loop is for the 200 - 500kHz band. About how much is the impedance
of such an antenna? Thanks.

Al

Hi Greg,

I was also very surprised to see prefboard, especially if you take the price of an ALA into account! It is prefboard with Cu strips that are cut were needed (using a small drill). This, however, does not necessarily means a performance degradation (at least at these frequencies). The board is fully differential to ensure the high OIP2 number.

How many ALAs are sold everyday? I'm not so sure if it would be cheaper to make a dedicated board, but I could be wrong on that. It also allows more flexibility regarding component size etc. (I know, you can do that in PCB design as well, but in the end, you are designing you own prefboard).

If I'm not mistaken, I thought Wellbrook is a single person (Andy) company?

Regarding production time, the assembly limit is in winding the two transformers. That is a really really boring job ;)

Pat.


"Greg W:-)" <onegammyleg@...> wrote: Hi Pat

Thanks for the pic's.... BUT

It's built on perfboard !! ..that would have to be the most
unprofessional thing that I have ever seen in a commercial product.

And using perfboard is slow ,,if they had of used an etched board
assembly would be a LOT faster with less chance of construction failures.
This offsets the costs of a small etched board easily.

I thought Welbrook was much better than that ,,it really is backyard
standards of construction.

I think THAT is why they glue it all together , so you don't see their
work.

gregW:-)



=====================================================================

--- In loopantennas@..., Patrick Reynaert

wrote:

Hi Dominique,

I've placed some pictures of an opened ALA1530 on the photo section

of this group page. After two days carefull work, I finally got to the
circuit.

Pat.

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Al,
A folded dipole is around 300 ohms. This explains the use of 300 ohm twin
lead
on many TV antenna on old. If you really want to delve deeply into the topic
the
link below will give you more than needed with some programs that will crunch
the numbers.
_
()

Enjoy,

Eric

Hi Pat

Thanks for the pic's.... BUT

It's built on perfboard !! ..that would have to be the most
unprofessional thing that I have ever seen in a commercial product.

And using perfboard is slow ,,if they had of used an etched board
assembly would be a LOT faster with less chance of construction failures.
This offsets the costs of a small etched board easily.

I thought Welbrook was much better than that ,,it really is backyard
standards of construction.

I think THAT is why they glue it all together , so you don't see their
work.

gregW:-)



=====================================================================

--- In loopantennas@..., Patrick Reynaert <preynaert@...>
wrote:

Hi Dominique,

I've placed some pictures of an opened ALA1530 on the photo section

of this group page. After two days carefull work, I finally got to the
circuit.

Pat.

Hi Dominique,

It wasn't even mine antenna; I got a broken ALA from a friend.

Pat.


"D.Kremp" <dominique.kremp@...> wrote: Hi Pat,

Hope you did'nt do that especially for us !

Tell us what happened to your antenna !

See you



Dominique



_____

De : loopantennas@... [mailto:loopantennas@...] De
la part de Patrick Reynaert
Envoyé : samedi 10 mars 2007 18:31
? : loopantennas@...
Objet : RE: [loopantennas] Re: Active loop antenna



Hi Dominique,

I've placed some pictures of an opened ALA1530 on the photo section of this
group page. After two days carefull work, I finally got to the circuit.

Pat.

"D.Kremp"
wanadoo.fr> wrote: Hi Greg,

I have an ALA1530, an ALA100 and an AVA100, all from Wellbrook.

Very fine antennas indeed.

Of course I have tried to open the units and see the circuits ! Very
disappointing : the units are filled up with a sort of hard black wax which
makes impossible to see neither the components nor the circuit. That makes
of course the construction very safe for outdoor use.

But I think it's also very safe for the industrial secret !

Don't you think it's the main aim of the constructor Andy IKIN to prevent
any chinese imitation ?

Have a nice week end

Dominique

from Normandy/France

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