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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