On Oct 17, 10:32*pm, JimK wrote:
-*Terminate the random wire away from the
- electrical noise near the receiver by using
- co-ax and the balun.

Generally a Balun works best along with a
good earthen Ground {connection}.
*.

Dave and RHF, thanks. I'll read up on the balun. What is the purpose
of impedence (or RF?) matching between random wire and coax?

Thanks,
Jim

JIM K - Here is a visualization explanation
that is not technically correct.

The Long Wire Matching Transformer {Balun/UnUn}
incorporates a HI-Z Winding and a LO-Z Winding
plus an effective {efficient} means of 'coupling'
{energy transfer} which is usually a Ferrite Core.
-coupling-
The 'nominal' Impedance of a long wire {random wire}
Antenna is 450~500 Ohms [HI-Z] and captures the
RF Signal {relative Higher Voltage and Lower Current}.
-to-
The 'nominal' Impedance of a Coax Cable is 50~75
Ohms [LO-Z] and conducts the RF Signal {relative
Lower Voltage and Higher Current}.

NOTE - The Balun/UnUn is an Matching Transformer
that is designed to work/operate at Radio Frequencies.

Consider the common wall-wart 120VAC to 6VDC
that is designed to work/operate at AC Power
{50~60 Hz} Low Frequency : It too is a Transformer.

For a more technical explanation of Baluns read :

Electrical Impedance
http://en.wikipedia.org/wiki/Electrical_impedance

Characteristic {Nominal} Impedance
http://en.wikipedia.org/wiki/Characteristic_impedance

Impedance Matching
http://en.wikipedia.org/wiki/Impedance_matching

Balun
http://en.wikipedia.org/wiki/Balun

Impedance Matching Transformers
http://www.bcae1.com/trnimpmt.htm
http://www.allaboutcircuits.com/vol_2/chpt_9/7.html

Impedance Matching Transformers for Receiving Antennas
http://www.dxing.info/equipment/impe...ing_bryant.pdf

How RF Transformers Work
http://www.minicircuits.com/pages/pdfs/howxfmerwork.pdf
* About RF Transformers
http://www.minicircuits.com/pages/pdfs/tran14-2.pdf

Wide Band RF Transformers
http://www.electronics-tutorials.com...ansformers.htm

Broadband Receiving Antenna Matching
http://www.qsl.net/wa1ion/bev/bb_antenna_matching.pdf

hope this helps - iane ~ RHF