DX Engineering DXE-RFCC-1 Instruction Manual

Feedline Current Choke

1200 Southeast Ave. - Tallmadge, OH 44278 USA

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

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Receive

RFCC-1

DXE-RFCC-1-INS-Revision 3

 DX Engineering 2020

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Introduction

The DX Engineering RFCC-1 receive feedline common-mode choke is the most effective solution
to common-mode noise or unwanted signal ingress available to date. The DX Engineering RFCC-1
provides thousands of ohms isolation between the input and output coaxial shield connections while
passing desired signals, including dc or low frequency ac control signals. The RFCC-1 has
extremely high isolation impedance which effectively blocks common-mode noise or unwanted
signals, even in the presence of very poor grounding.

The RFCC-1 is effective from 300 kHz to 30 MHz. It comes with standard CATV type “F” female
connectors, although it can be used in any 50 to 75 ohm receiving system. The RFCC-1 is a passive
device, therefore requires no power to operate.

Application

Low noise receive antennas are traditionally located away from electrical wiring and other noise
sources. Unfortunately, noise and other unwanted signals have a direct path to your low-noise
antenna through the feedline shield connections between the station equipment and antenna.
Unwanted signals can also energize the outside of the feedline shield, and this undesired signal
energy can be conducted directly to the receiving antenna. This can reduce antenna directivity.
Unless you have a perfect zero-resistance RF ground at the antenna, some of the common-mode
noise or unwanted signals from the feedline shield will make it into the antenna. While RF
suppression beads over the feedline can help, their impedance is generally very low, limiting the
amount of isolation they can provide. Bead effectiveness is significantly dependent on feedline and
antenna grounding.

Do not transmit through the RFCC-1 as damage to the unit will occur.

Note: The DXE-RFCC is not recommended for use with the DXE-RF-PRO-1B since there is large
amount of current drawn by the RF-PRO-1B which will cause a severe voltage drop if the RFCC is
used. An alternate solution would be to use #31 ferrite cores to create a common mode choke with
nine wraps of coax.

Installation

One of the RFCC-1 connectors is isolated from the case and can be identified by the white washer
under the connector. The other connector is grounded to the case. The longest feedline cable run
should always be attached to the grounded connector, and the RFCC-1 should always be grounded
to its own independent ground rod. We recommend at least one ½ to ¾” diameter copper ground
rod at least 5 feet long.

The optimum location for the RFCC-1, in most applications, is near the antenna. Place the RFCC-1
close to the antenna, but before the feedline parallels any antenna element. For a small loop antenna
with the feedline dropping vertically from the loop, install the RFCC-1 approximately one to two
loop diameters below the loop.

If you have a Beverage, Flag, Pennant, or K9AY antenna, install the RFCC-1 15 to 30 feet away.

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