MFJ MFJ-842 Instruction Manual

Model MFJ-842

INSTRUCTION MANUAL

CAUTION: Read All Instructions Before Operating Equipment

MFJ ENTERPRISES, INC.

Tel: [phone] Fax: [phone]

VERSION 1A

300 Industrial Park Road

Starkville, MS 39759 USA

COPYRIGHT 2006 MFJ ENTERPRISES, INC.

C

DISCLAIMER

Information in this manual is designed for user purposes only and is not intended to
supersede information contained in customer regulations, technical manuals/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.

MFJ-842 Mobile VHF/UHF SWR/Wattmeter Instruction Manual

MFJ-842 Mobile HF/VHF SWR/Wattmeter

Introduction

The MFJ-842 Mobile VHF/UHF SWR/Wattmeter measures forward and reflected power
and SWR simultaneously and is designed to operate on 140-525 MHz. The MFJ-842 has
two power scales, which are selected with a push button switch. The high power scale
measures 0-150 Watts forward power and 0- 50 Watts reflected power. The low power
scale measures 0-15 Watts forward power and 0-5 Watts reflected power. The MFJ-842
utilizes an illuminated Cross-Needle meter to read the SWR from 1:1 to ∞. This compact
SWR/Wattmeter is rugged enough to take the abuse of brutal mobile and portable
operation.

Specifications

Connectors: UHF (M type)
Dimensions: 3.35”W x 3.43”H x 3.74”D
Weight: 0.62 lb
Lamp Input Power: 12 VDC

Frequency Range: 140-525 MHz
Input Impedance: 50 Ohms
Power Range: 15 and 150 Watts Forward Power

5 and 50 Watts Reflected Power

Power Accuracy: 10% at full scale
Minimum Input Power: 1 Watts

Installation

1. Connect your transmitter to the connector labeled TX. on the back of the unit and
connect your antenna to the connector labeled ANT. on the back of the unit. It is
important that you use good quality coax and properly installed connectors.

2. An internal lamp backlights the meter scale. The lamp circuit requires 12 VDC
supply such as the MFJ-1312B. Use a 2.1 mm coaxial plug with the center
conductor positive and the sleeve ground.

3. To measure the power output capability of a transmitter/amplifier you should
connect a quality 50-ohm dummy load to the ANT. connector of the MFJ-842.

2