DX Engineering DXE-BFS-1 Instructions manual

Beverage Feedpoint Matching

System

DXE-BFS-1

Patent Pending

DXE-BFS-1-INS Revision 3c

© DX Engineering 2017

1200 Southeast Ave. - Tallmadge, OH 44278 USA

Phone: [phone] ∙ Tech Support and International: [phone]

Fax: [phone] ∙ E-mail: [e-mail]

Introduction

The DXE-BFS-1 is a single-wire, single direction Beverage Feed System. This W8JI design is
immune to strong signal overload and core saturation common in multi-transmitter contesting
environments, and is used by winning contest stations and low-band DXers. The unit uses an
isolated-winding, matching transformer system to significantly increase the signal-to-noise ratio in
Beverage and other high impedance antennas.

The DXE-BFS-1 works with antenna impedances from 400 to 500 Ω.
Included with the DXE-BFS-1 is a 470 Ω, 2-Watt non-inductive
termination resistor that withstands nearby lightning strikes significantly
better than hard to find carbon composition resistors. DX Engineering has
replacement resistors available, part number DXE-ECM-R470-2.

The feedline impedance of the DXE-BFS-1 is optimized for 75 Ω,
however, any feedline between 30 Ω and 100 Ω can be used. While not
intended for transmitting, the DXE-BFS-1 can withstand power levels of
20 watts continuously, 200 watts for 5 seconds or the power rating of the termination resistor,
whichever is less. The DXE-BFS-1 coaxial cable connection uses an industry standard CATV F
type connector.

The DXE-BFS-1 sets itself apart from competitive products by combining quality components and
superior technology inside a compact metal housing.

Features

 100 kHz to 30 MHz operating range
 Integral spark gaps built into the internal printed circuit board minimize damage from

lightning

 Wing nut terminals eliminate soldering
 Metal housings used for superior shielding and improved life
 Flange-mount holes for easy mounting
 Ground isolated secondary essential for building beverage arrays and can be connected with

normal or reverse phase

 RoHS compliant assembly

The DXE-BFS-1 uses an isolated-winding, matching transformer system that significantly increases
the signal to noise ratio in Beverage and other high impedance antennas. This unit is immune to
strong signal overload and core saturation common in multi-transmitter contesting environments,
and is used by winning contest stations and low-band DXers.

Coaxial Cable and Connectors

The feedpoint matching system is optimized for 75 Ω feedline. This allows the use of 75 Ω CATV
type coaxial cable and F style connectors. We recommend using high quality “flooded” 75 Ω RG-6
type coaxial cable, DX Engineering part number DXE-F6-CTL or DXE-F6-1000. Flooded coaxial

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cables have the distinct advantage of automatically sealing small accidental cuts or lacerations of
the jacket. Flooding also prevents shield contamination and can be direct-buried. To ensure
weatherproof connections, use Snap-N-Seal connectors. DX Engineering part number DXE-SNS6-
25 contains 25 Snap-N-Seal connectors. The Snap-N-Seal connectors cannot be installed with
normal crimping tools or pliers, so an installation tool like the DXE-SNS-CT1 is essential for
proper connector installation.

Additional Requirements

Please note you will need the following items (not included in this package) to install and operate
the DXE-BFS-1 antenna:

 Antenna wire: You will need a minimum of 3/8 wavelength of wire of any gauge between #8 and

#20.

 Ground rods: Use at least one 5-ft copper rod.
 Insulators and supports: Insulators and supports are required to support the antenna wire 5 to 10 feet

above ground. Supports can be metallic but the antenna wire must be insulated from them.

Specifications

Operating Frequency: 100 KHz to 30 MHz
Input Impedance: 400-500 Ω
Output Impedance: 30-100 Ω (75 Ω recommended)
Common Mode Isolation: 20-30 dB (feedline and antenna)
Power Handling: 20 watts continuously or 200 watts for 5 seconds
Termination Resistance: 400-500 Ω

Installation

We strongly suggest that you read the entire DXE-BFS-1 manual before installing the antenna, and
make sure you understand the concepts outlined in the sidebar (below) that are critical to proper
operation.

Isolation

The DXE-BFS-1 operates on the principle of a transformer with isolated antenna and feedline
connections. This prevents the feedline from contributing unwanted electrical noise or signals to the
receiver. Many antenna enthusiasts unwittingly connect their feedline to their matching system
housing, not realizing that the practice simply makes the antenna longer and increases unwanted
signals. The DXE-BFS-1 solves this problem by insulating the connection lugs from the housing,
which also isolates the antenna from the feedline.

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Performance Factors

Critical Installation Information

Transmitting The DXE-BFS-1 is designed for use in receiving antennas: do not transmit

through the DXE-BFS-1 with more power than the rating of the termination resistor (a 2-watt
resistor is included with the unit). This system will not be damaged by transmissions from
other antennas as long as the DXE-BFS-1 is more than one half wavelength from the
transmitting antenna and the power is less than 1500 watts.

Grounding To ground the antenna, run a wire from the – terminal of the DXE-BFS-1 to the
ground rod or rods. The antenna system is NOT grounded through the metal case. Feedline
terminals are engineered to be ground independent of the metal housing and whatever that
housing is mounted on. DO NOT ground the case to the antenna ground, since that will
connect the feedline shield to the antenna system and possibly increase noise or reduce
directivity of the antenna.

Termination The far end of the antenna must be properly terminated, or the antenna will not
have the best F/B ratio. Failure to terminate the antenna will generally result in a reduction of
S/N ratio as high as 20 dB, depending on noise arrival direction. For best results, use the
termination resistor included in this package.

Antenna Performance Based on Length

Antenna Length

160 Meter Band

80 Meter Band

40 Meter Band

20 Meter Band

120 Feet

Too Short

Marginal

Good

Good

240 Feet

Marginal

Good

Best

Good

360 Feet

Fair

Best

Best

Good

480 Feet

Good

Best

Good

Good

600 Feet

Better

Good

Good

Good - Marginal

720 Feet

Best

Good

Good

Marginal

For an effective Beverage antenna, you will need at least 3/8 wavelength of wire. Acceptable wire
types include galvanized or cadmium-plated steel electric fence wiring, stranded or solid copper
wire, and steel-core wires like copperweld. Avoid wire designed for welding applications. The line
with the best mechanical and electrical characteristics is generally #16 gauge copper clad steel
(copperweld) wire. Aluminum wires will work, but connections and splices are problematic due to
the formation of aluminum oxide.

Antenna Length

The chart below shows relative performance of Beverage antennas based on wire length:

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