In article .com,
"RHF" wrote:

For One and All,

Two Matching Transformers and Three Hook-Ups :
http://groups.yahoo.com/group/Shortw...a/message/6647

1. Basic Balance (Dipole) Antenna to Coax Cable via a BALUN type
Matching Transformer with the Ground connected to the Shield.
Note - Parallel Matching Transformer Windings (Transformer).

*-------------Antenna Wire------------00....Rope.....
/
/
/ /*---- Inner Wire C/C
/ /
/ /
/ /*GR===== Shield C/C
/
/
*-------------Antenna Wire------------00....Rope.....



2. Basic Un-Balance Single Wire (Random) Antenna to Coax Cable
via a UnUn type Matching Transformer with a "Common" Ground
connected to the Shield. [ Both UnUn Winding share a Common
Ground Connection internally or externally. ]
Note - Parallel Matching Transformer Windings (Transformer).

*-------------Antenna Wire------------00....Rope.....
/
/
/
/
/ /*---- Inner Wire C/C
/ /
/ /
/ /*===== Shield C/C
**
GR



3. Basic Un-Balance Single Wire (Random) Antenna to Coax Cable
via a UnUn type Matching Transformer with a "Common" Ground
connected to the Shield. [ Both UnUn Windings share a Internal
Common Ground Connection. ]
Note - Series Matching Transformer Windings (Auto-Transformer).

*-------------Antenna Wire-----------00....Rope.....
/
/
/
/
/*------- Inner Wire C/C
/
/
/*======== Shield C/C
*
GR

NOTE - The same Parallel-Winding Matching Transformer can be
used for # 1 and # 2. The # 3 is designed to use one way.

SNIP

Basically with single wire antennas you need to do two things.
1. Provide a ground or counterpoise element.
2. Block the coax shield from behaving as an RF return.

You have to do both so the coax shield does not become a RF return for
the antenna or power line noise through the radio will raise the
receiving noise floor.

Using an outdoor ground rod or laying a wire under a random wire as a
minimum for a RF antenna return. The BALUN will help match the wire
impedance to the coax and provide some isolation on the shield depending
on construction. You can always add another RF choke on the shield some
distance from the BALUN or transformer in order to further isolate the
coax shield from the antenna system.

--
Telamon
Ventura, California