antsys

SWL Antenna Distribution System Copywrite 1997, 2007 - Alan R. Klase - All rights reserved.

I have developed a methodology for connecting multiple LF/MF/HF receivers to a single antenna via readily available and inexpensive 75-ohm TV cable. Custom made baluns and splitters provide impedance matching and prevent interaction between receivers. The following drawing shows a representative system. Construction details are given below.

UPDATED INFO

Broad-namd transformers based on binocular coils: BALUNS
Simple, effective active antenna: ACTIVE
Order cores from ByteMark BN-43-202 is now known as B-202-43

4:1 Balun

Provides matching from random wire antenna to coax.
Also allows separation of antenna ground from building ground to prevent noise pickup.

Grounding Block

Installed at entry point to building to head off lightning.
Standard CATV device
Electrical code calls for connection to an 8-foot ground rod.

3-dB Hybrid Splitter

Divides signal between two outputs and maintains 75-ohm impedance.
Provides 30dB isolation between outputs.
Broadband: 30KHz to 30MHz.
CATV splitters don't work well below 10MHz.

A/B Switch

In this case, allows comparison of the new antenna to the old "reference" antenna.
Standard CATV device.

4:1 Balun

Matches 75-ohm cable to old fashioned A-A-G inputs which are usually 300-400 ohms.
Same component as above.

Loop Coupler

Couples 75-ohm coax to receivers with internal loop antennas, e.g. table radios.

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