MFJ MFJ-923 Instruction Manual

Dual Band Tuner

Model MFJ-923

TM

CAUTION: Read All Instructions Before Operating Equipment !

MFJ ENTERPRISES, INC.

Tel: [phone] Fax: [phone]

VERSION 1B

INSTRUCTION MANUAL

300 Industrial Park Road

Starkville, MS 39759 USA

COPYRIGHT 2012 MFJ ENT ER PR IS ES , INC .

Disclaimer

Information in this manual is designed for user purposes only and is not
intended to supersede information contained in customer regulations,
technical manual/documents, positional handbooks, or other official
publications. The copy of this manual provided to the customer will not be
updated to reflect current data.

Customers using this manual should report errors or omissions,
recommendations for improvements, or other comments to MFJ
Enterprises, 300 Industrial Park Road, Starkville, MS 39759.
Phone: [phone]; FAX: [phone].
Business Hours: M-F 8-4:30 CST.

2

The MFJ-923 antenna tuner was designed with today’s dual band radios in mind.

IN T R O D U C T IO N

The M FJ-9 2 3 Antenna Tuner w as desig n e d w ith today’s d u a l band ra d io s in
m ind. This unit has a si ng le input co n n e c tor so th a t it w ill easily c o nnec t to yo u r
dual band tra nsceiv e r. T w o outp u t co n n e c tors giv e yo u the optio n of using a
dual band ante nna or tw o single band ante nnas for m a x im um pe rformance. A
switch on the b a c k o f the unit allow s you to se lect two sin g le or o ne d ual band
antenna. This option el im inates the ne e d for a duplexe r w h e n op e r atin g two
antenna s with one rad io . T h e bu ilt in po wer meter ha s three selectable po w e r
se tti ng s fo r ea c h band.

INSTALLATION

The MFJ-923 should be installed between the transmitter and antenna.

1. Locate the tuner in a convenient location at the operating position.

2. Use a 50 ohm coaxial cable to connect the transmitter or transceiver to the
SO-239 labeled TRANSMITTER on the back of the tuner.

3. Connect an antenna feed to the appropriate tuner output:

(A) If using a dual band antenna then select either of the output connectors.

When the output switch is in the dual band position, both connectors are the
same and either will work. Only use one of the connectors, do not connect
anything else to the other. Leave it open.

This unit has a single input connector so that it ill easily connect to your dual band
transceiver. Two output connectors give you the option of using a dual band antenna
or two single band antennas for maximum performance. A switch on the back of
the unit allows you to select the antenna option. This eliminates the need for a
duplexer when operating two separate antennas with one radio. The built in power
meter has three selectable ranges for each band.

Dual band

antenna

ONE DUAL BAND ANTENNA

UHF

440MHz

Dual Band

Antenna

146MHz

Two Single

Band antenna

METER

LAMP

POWER

12VDC

-

+

3

VHF

300 300

TRANSMITTER

300 300

UHF

VHF

Radio

REFLECTED

FORWARD

300

UHF

30

VHF

300

VHF

30

300

30

300

30

UHF