Topband: 160mtr loop for receive only
Chris at G3SVL.com
Tue Sep 26 04:55:59 EDT 2006
Here's some comments
At 00:14 26/09/2006, AS5VJ wrote:
>Would I be wasting my time on a loop antenna for 160?
There are folks who rave over them and others who say they add
nothing. You won't know until you try it at your QTH.
>It just doesn't seem right to be able to get by with so little length of wire.
The signal levels will be way down on a larger antenna - but on 160m
that doesn't matter because the cosmic and man-made noise will
certainly be above your receiver noise floor. Some people advocate a
10 - 20dB pre-amp but most get by without. (I guess a pre-amp
violates the XYL's embargo!)
>I have just read about a loop antenna for 160 .... I have no caps
>or boxes ...... so I was wondering if I could just go to an F
>connector T and come into the shack to my MFJ-949B tuner and
>accomplish the same thing the capactor would do at the antenna.
No - the capacitor is there to tune the loop and while I'm sure you
will hear signals using your approach they will most likely be being
picked up on the feedline!
You should take a look at Tom's (W8JI) excellent pages on loops at
http://www.w8ji.com/magnetic_receiving_loops.htm to understand their
operation, and Bob (GU4YOX) site for a clear and positive build and
performance report with audio recording of his loop in operation
As for parts, the box is only there to provide weatherproofing and a
discarded pill box or biscuit tin will do. Hey, even a plastic bag
will work if you can support the components mechanically. Someone on
this reflector who lives on your side of the Atlantic would surely
donate some variable caps - the compression types are about $1 each
at flea markets - or find an old broadcast radio and remove the
tuning capacitor. Forget the F connectors they are more trouble than
they are worth - just solder everything together.
Send us the reports of how it works ......
73 Chris G3SVL
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