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