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Elecraft KXFL3 Filter Option User Manual

Elecraft, Kx3 kxfl3 roofing dual-bandwidth filter, Introduction

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Elecraft

®

KX3

KXFL3 Roofing Dual-Bandwidth Filter

Installation and Calibration Instructions

Revision A2, June 14, 2012

Copyright © 2012, Elecraft, Inc., All Rights Reserved

Introduction

The KXFL3 is a high-performance, narrow-band analog filter module that helps reject strong signals that could
cause receiver blocking (desense) or intermodulation distortion. It adds two additional bandwidths to the KX3
that are automatically selected as the receive bandwidth is adjusted.

Installation involves installing the KXFL3 plug-in module in your KX3 and then calibrating the filter for proper
operation. No test equipment is required to calibrate the filter although a signal generator may be used, if
available.

CAUTION

The KXFL3 module and many components inside your KX3 may be damaged by
Electrostatic Discharge (ESD) simply by touching them or a circuit board containing
them unless you take specific steps to prevent such damage. See Preventing
Electrostatic Discharge Damage
on page 2 before opening the package containing the
KXFL3 module or working inside your KX3.

Specifications

Filter type: Two filters, each having dual balanced Butterworth sections

Gain/phase match: Typ. 0.1%. Additional matching accuracy provided by DSP
techniques.

FL2: 1500 or 3000 Hz low-pass, depending on demodulation method in use.*

FL1: 500 or 1000 Hz low-pass, depending on demodulation method in use.*

* The narrower bandwidths apply in all modes except when Weaver-mode SSB demodulation is
being used. Filters switch in at predetermined points in each mode, varying with passband center
pitch, width, and shift amount.