In article om,
"Jeroen" wrote:

Telamon wrote:

The first link is a manually tuned loop and the second is a motorized
version of the same. A tuned loop will be quieter than a broadband loop
design I posted earlier.

I posted the second link as it offers more information about the
circumvence of the loop, and the possibility about making the loop
multiple turns, and how the distance between those tunrs affect the
range the loops works best for. Those are all info not present in the
first.

The drawback with the tuned loop is you have to tune it along with the
radio complicating the operation of tuning in a station.

I have it in the livingroom becuase of that, haha. It's indeed a bit
less practical. The overall bandwidth thats tuned into is about 100Khz.
So its doable to browse the 60 meter band for example.

Looking at the first link I think the design would work better if there
was more separation between the pickup loop and the tuned loop. I would
attach the pickup loop on the other side of the PVC pipe.

Hmm that is interesting, and something I want to experiemnt with. In
the testing phase, with simply holding an antenna of a portable close
to the loop, I found that the closer, the better...

The second suggestion is to use a series 50 ohm resistor from the coax
center conductor to the pickup loop. This may not do much other than
sharpen the peak of the tuning response.

From a SWL in the Netehrlands I've understood that the whole point of
using the coupling loop is to make the input into the antenna 50 ohm.
Why would adding a 50 ohm resistor improve things further?

Thanks for your help, learning so much about antenna's doing all this
building, experiementing and asking around!

The pickup loop will look like a short on the end of the coax at some
frequencies and the resistor will cause the impedance to be a minimum of
50 ohms.

You don't want the two loops to actually touch each other and mounting
the pickup on the other side of the PVC pipe is an easy way to
accomplish that.

--
Telamon
Ventura, California

Telamon wrote:

You don't want the two loops to actually touch each other and mounting
the pickup on the other side of the PVC pipe is an easy way to
accomplish that.

Yes, but why not allow them to touch eachother? What's the reason for
it?

Just hoping to get a (physics) reason for why they shouldnt be too
close togheter, jst to further udnerstand the nature of the thing
better I havent came acros any descriptions that said they shouldnt
be too close, so I'm really curious.

Thanks,

Jeroen

In article .com,
"Jeroen" wrote:

Telamon wrote:

You don't want the two loops to actually touch each other and mounting
the pickup on the other side of the PVC pipe is an easy way to
accomplish that.

Yes, but why not allow them to touch eachother? What's the reason for
it?

Just hoping to get a (physics) reason for why they shouldnt be too
close togheter, jst to further udnerstand the nature of the thing
better I havent came acros any descriptions that said they shouldnt
be too close, so I'm really curious.

Two things referring to the link http://www.kr1st.com/swlloop.htm

1. The tuned loop and pickup loop are supposed to couple magnetically.
The tuned loop is bare copper and it looks like the pickup is made of
bare wire so if they touch they will have a direct circuit connection.
If you use magnet wire for the pickup you are counting on a thin layer
of enamel paint to insulate one from the other, which can easily be
abraded.

2. One parameter controlling Magnetic coupling between the loops is
distance. You already know this and the loop will tune a little sharper
if the pickup loop does not load it as much as when the loops are
physically together.

--
Telamon
Ventura, California

Ah ok. Obviously at least one of the loops is insulated here (that
wouldve been a joke ). I'll experiment with the distance here and
see what differences it makes.

I also noted that different setups can affect different type of
stations in different ways again. What can benefit stations hidden in
static (tropical dx) can worse reception of SSB stations that are
strong, and ofcourse, the other way around.

Fun stuff, making your own antenna for sure!