MFJ MFJ-219B User Manual

MFJ-219/219N 440 MHz UHF SWR Analyzer

TABLE OF CONTENTS

Introduction ..................................................................................................................2

Powering The MFJ-219/219N......................................................................................3

Battery Installation .......................................................................................................3

Operation Of The MFJ-219/219N................................................................................4

SWR and the MFJ-219/219N...........................................................................4

Measuring SWR ...............................................................................................5

Adjusting Simple Antennas..........................................................................................5

Dipoles..............................................................................................................5

Quad Elements..................................................................................................6

Verticals............................................................................................................6

Tuning an Antenna...........................................................................................6

Measuring the Feedpoint Resistance of Antennas ...........................................6

Testing and Tuning Stubs and Transmission Lines......................................................7

Velocity Factor of Transmission Lines ............................................................8

Impedance of Transmission Lines....................................................................9

Estimating transmission line loss.....................................................................9

Adjusting Matching Networks .....................................................................................10

Adjusting Amplifier Networks.........................................................................10

Finding the Frequency of the MFJ-219/219N..............................................................10

Using the MFJ-219/219N as a Signal Source ..............................................................11

Technical Assistance....................................................................................................11

MFJ-219/219N Instruction Manual 440MHz UHF SWR Analyzer

INTRODUCTION

The MFJ-219/219N SWR Analyzer is an easy to operate, versatile test instrument for
analyzing nearly any 50Ω RF system on frequencies between 420 and 450 MHz. In addition
the MFJ-219/219N can be used as a UHF signal source.

The MFJ-219/219N combines three basic circuits; a UHF oscillator, a 50Ω RF bridge, and a
calibrated bridge unbalance indicator. This combination of circuits allows measurement of
the SWR (referenced to 50Ω) of any load connected to the ANTENNA connector.

The MFJ-219/219N covers the entire 70 cm amateur band. The dial calibration is
approximate and for reference only. The actual frequency may vary from what is marked on
the front panel.

The MFJ-219 has a SO-239 socket for the antenna connector. The MFJ-219N has an N type
plug for the antenna connector. The only difference between the MFJ-219 and MFJ-219N are
the connectors.

A frequency counter, such as the MFJ-346, can be connected to the "FREQUENCY OUT"
jack (RCA phono) for a more accurate reading of the frequency. As an alternative to a
frequency counter, you can tune in the output with a broad bandwidth UHF receiver. See the
section on locating the MFJ-219/219N frequency with a receiver.

The MFJ-219/219N can be used to adjust or measure the following:

• Antennas: SWR, resonant frequency, bandwidth

• Amplifiers: Input and output networks

• Coaxial transmission lines: SWR, velocity factor, losses, resonance

• Networks: SWR, resonant frequency, bandwidth

• Stubs: Resonant frequency

WARNING: Please read this manual thoroughly before using this instrument. Failure

to follow the operating instructions may cause false readings or cause
damage to this unit.

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MFJ-219/219N Instruction Manual 440MHz UHF SWR Analyzer

POWERING THE MFJ-219/219N

The MFJ-219/219N requires between 7 and 18 volts for proper operation. Any power supply
used with the MFJ-219/219N must be capable of supplying 100 mA of current. An optional
power supply, the MFJ-1312B, is available from MFJ.

The MFJ-219/219N has a standard 2.1 mm female receptacle at the bottom of the case. This
jack is labeled "12VDC" and has the word "POWER" near it. A pictorial polarity marking
appears on the case near the power jack. The outside conductor of the plug must connect to
the negative supply voltage and the center conductor of the plug must connect to the positive
voltage. If a 9 volt battery is connected, it will be automatically disconnected when an
external power plug is inserted in this jack.

SWR measurement will be inaccurate when the supply voltage falls below 7 volts. To avoid
false readings maintain fresh batteries and always use the correct power supply.

WARNING: Never apply AC, unfiltered or incorrectly polarized DC to this jack. Peak

voltage must never exceed 18 volts.

BATTERY INSTALLATION

To install a battery first turn the unit OFF. Remove the 8 phillips head screws on each side of
the case. There is a plastic tube on the battery clips that insulates them from the inside of the
unit. Slide the insulator down on the wire before installing a battery so that it will not be lost.
The insulator must be on the battery clips when there is not a battery in the unit. Insert the
battery securely into the battery holder.

+ Carefully check to ensure the following:

• The battery leads are positioned so that they do not interfere with the variable capacitor.

• The wires are not pinched between the cover and the chassis.

After the battery is installed, reinstall the 8 cover screws.

MFJ recommends the use of 2 9V ALKALINE (or rechargeable nicad) batteries to reduce the
risk of equipment damage from battery leakage. Avoid leaving any batteries in this unit
during periods of extended storage. Remove weak batteries immediately!

When using a battery with this unit, quickly make a measurement and turn the unit off. If the
unit is left on for long periods of time, battery life may be short.

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