MFJ MFJ-842 Instruction Manual Download Page 3

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

 

 

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 

 

 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 

 

 

 

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. 

 
 
 
 
 

Summary of Contents for MFJ-842

Page 1: ...AUTION Read All Instructions Before Operating Equipment MFJ ENTERPRISES INC 300 Industrial Park Road Starkville MS 39759 USA Tel 662 323 5869 Fax 662 323 6551 COPYRIGHT 2006 MFJ ENTERPRISES INC C Mode...

Page 2: ...tional 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 omissio...

Page 3: ...cifications 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 Co...

Page 4: ...n 30 and 150 Watts In the 15W out position the forward power scale must be divided by 10 Each picket represents 0 5 Watt below 3 Watts 1 Watts from 3 to 15 Watts 3 Reflected power is displayed on the...

Page 5: ...ttom Refer to Figure 2 for the Test Setup and refer to the Trim Pot Location in Figure 3 for trim pot location 2 Connect the Test Setup equipment as shown in Figure 2 Use a 50 ohm dummy load for the a...

Page 6: ...ference meter Adjust the LO REF trim pot to set the reflected power scale to 5 Watts 8 SWR requires no calibration Read SWR directly from the crossing point of the forward and reflected needles Figure...

Page 7: ...0549 or the MFJ Factory at 662 323 5869 You will be best helped if you have your unit manual and all information on your station handy so you can answer any questions the technicians may ask You can a...

Page 8: ...MFJ 842 Manual Version 1A Printed In U S A 300 Industrial Park Road Starkville MS 39759...

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