Richard, I share your enthusiasm for the AMA loops, but possibly you have
never seen the I3VHF loops.
Indeed it does use a gamma match, but it also uses thicker aluminum and a
much more hefty capacitor.
The AMA uses a variable capacitor. That is its biggest limitation - that
and the smaller material used in the loop.
The Italian loop uses huge aluminum plates that are simply pushed in or out
of each other.
They can handle a lot more power than traditional variable capacitors.
The biggest one uses 3 inch tubing. But the thing is a monster; weighs more
than I do and I'm no featherweight!
However for most people, if you are in a situation where you have to use a
loop, you probably should not be running more than 100w anyway. In that
case the AMA is great.
There is also an automatic tuning option for the Italian loops. Simply dial
in the frequency you want to use and they tune themselves. Sexy. But for a
price.
I suspect my $200 shipping estimate to be very low. And that was only for
the smallest loop.
A larger loop will cost at least $500 to ship.
The best thing to do is build your own, but don't skimp on the cost of good
quality components.
Unless you are a whiz at building mechanical things, the vacuum variable
like Jim mentioned is the best way to go.
I've seen some good suggestions in the states for making loops, based on
using PVC tubing and wrapping it with thin flat copper plates.
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Richard
Tschur
Sent: Sunday, April 27, 2014 9:51 AM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] New Jupiter on its Way _ A Few Questions
I personally reckon, the Kaeferlein loops are the best on the market!
The one from Italy I believe uses a Gamma Match for feeding the antenna and
that might be not the best solution for a mag loop. I know Matthias
personally, a very nice guy and he worked with Kaeferlein as a teenager, to
earn some pocket money, so he is well aware of the technics and mechanics.
But apart from that, the crucial thing is to build them proper. I would make
them out of one piece and round! But that is only my opinion. As I said, I
have very good experience with mag loops and for someone with no space, they
are perfect. Yes, shipping is a big problem, but I guess, if you can spend
1200 -1500 Euros on an antenna, the extra 200 Euros shipping wouldn't be a
problem. I got my 2 loops shipped to Australia in a crate, but there was of
course other stuff in it as well. And for sure, I will never sell them, even
though I have people asking me about them, you never know what happens in
the future and I have to move in to an appartment or retirement village and
then I can use them again ;-)!
Btw, you find ama antennas quite often cheap for sale in cqdl, I got mine
for a swap of a Gap Challenger and never regretted it.
Enough of that.
73's
Richard
On 27/04/14 16:07, Rick - DJ0IP / NJ0IP wrote:
> Richard's advice is sound.
>
> Kaeferlein "made" good loops.
> However he's gone.
> His successor is Matthias Beese (DH6MM) and he still makes and sells
> the same quality of good loops.
>
> The commercial loop I tested and then used for many years was the
> Kaeferlein AMA-8.
> However as I said, it was actually too large to use indoors.
> I couldn't get it to work on 80m until moving it outdoors.
>
> NOW THE PROBLEM: Shipping cost to the states is probably about $200
> or more for even the smallest loop.
>
> There is also an Italian company making great loops.
> They are made by I3VHF.
> See: http://www.ciromazzoni.com/English/Loop%20Antenna.htm
> These will handle more power than the Kaeferlein loops. Cost more too!
> BUT AGAIN, shipping cost is huge on these.
> DOWNLOAD: (English language) his 48-page document on these antennas
> and see for yourself.
>
> The guy in my club I spoke of earlier with the 80m loop is running the
> "MIDI" loop from this company. Great product if you don't mind
> spending
> $1700 on an antenna.
>
> I am unaware of a source for good loops like these in the states.
> Business opportunity? (hi)
>
> 73 - Rick, DJ0IP
> (Nr. Frankfurt am Main)
>
>
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of
> Richard Tschur
> Sent: Sunday, April 27, 2014 1:57 AM
> To: Discussion of Ten-Tec Equipment
> Subject: Re: [TenTec] New Jupiter on its Way _ A Few Questions
>
> Hi all,
> a really good quality magnetic loop is available from Kaeferlein in
Germany!
> I have one with 80cm in diameter and it can handle up to 500Watts and
> it performs really well. They are not cheap, but they do perform. I
> bought mine used years ago for like 300 german Marks (good old
> times;-)), and i had great contacts on it. For example, the antenna
> was mounted about 50 cm above ground between the houses and i had a
> contact from Melbourne VK to Italy with 100 watts. But the important
> thing is, from what I've been told, no joins, one loop out of
> aluminium with at least 33mm diameter. This Kaeferlein guy is sort of a
pioneer with loops, he made them for decades.
> Just my take on them, so if you have no space, go for a good quality
> loop, you can put them nearly everywhere, in the garage, in the
> basement, height is not really critical, from what I have experienced.
Just my take on it.
> Here is the link to Kaeferleins web side www.ama-antennen.de
> Unfortunately only in german, but I think pretty much self explaining.
> I forgot to mention: the loop I have covers 13.5 to 30 MHz. I have
> another one from DJ0HV, he makes sort of homebrew semi comercial, this
> one is 2 m in diameter and covers 80 to 20 m and can handle up to 1 kw.
> The aluminium pipe is 60mm in diameter. Both of them are fully remote
> controllable! The only disadvantage in my opinion is, you have to
> retune every like 15 to 30 KHz, if you transmit, but you get a very
> selective and quiet antenna and in comparison with a dipol, it is
> maybe half to an s point lower! An that, you can compensate with a bit
> of juice behind the antenna ;-)!
>
> Regards and greetings from Down here
> Richard VK3KVK / DK3KVK
>
>
>
> On 27/04/14 06:49, Rockinghorse Winner (Terry) wrote:
>> K8JHR wrote:
>>> I have used the Wellbrook ALA-100M receiving loop for over a decade
>>> with good results at two locations. It is a "medium or large
>>> aperture" loop, because you supply whatever size wire loop you want.
>>> I used mine outside, but you could do it inside, but of course it
>>> tends to be more RF quiet the farther you get away from your
>>> dwelling. Wellbrook also makes a model that uses a 1 meter alum
>>> loop, which works well indoors. The loop does not have to be round
>>> or symmetrical, and you can use very light litz wire which is nearly
>>> invisible outside. They can also be used indoors, as in an attic,
>>> but you don't want to be listening on it when you are transmitting
>>> on it, if you cannot locate it at least 1/4 to 1/2 wavelength away
>>> from the transmitter antenna (which applies to all receive only
>>> antennas I
>>> suppose.) These work on the magnetic portion of the electromagnetic
>>> waves we work with, as does Rick's project.
>>>
>>> See The Wellbrook products here:
>>>
>>> http://www.wellbrook.uk.com/antennashop/
>>>
>>>
>>> I have also used a DX-Engineering active whip with good results. I
>>> have mine in the front yard, away from the transmitting antennas in
>>> the back yard, and it has a very low profile. These work on the
>>> electrical portion of the electromagnetic waves we work with. They
>>> have a single vertical whip model, and a dipole model, and you can
>>> see them here:
>>>
>>> single vertical model:
>>>
>>> http://www.dxengineering.com/parts/dxe-arav3-1p
>>>
>>> dipole model:
>>>
>>> http://www.dxengineering.com/parts/dxe-arah3-1p
>>>
>>>
>>> I have used both the Wellbrook loop and the DX-E active whip with
>>> good results as receive only HF antenna on my small suburban lot,
>>> although they are substantially more expensive than Rick's home brew
>>> project. I know several SWL's who have built similar loops to
>>> Rick's project, with good results. It is a classic.
>>>
>>> I went to the Wellbrook site. But the antenna you cited was 60" in
>>> diameter, too large for my room. Did you say they had some smaller
>>> loops? In any case, I'm going to try to build a receive mag loop
>>> according to the instructions Rick provided. It seems like a
>>> straight forward project that should take a few hours at most.
>>> Happy trails.
>>> ---------------------- K8JHR -----------------------
>>>
>>>
>>>
>>> On 4/25/2014 6:05 PM, Jim Allen wrote:
>>>> You might also consider the helically loaded loops that K8NDS has
>>>> been developing.
>>>
>>> _____________________________________________________
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>>> TenTec@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/tentec
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