MFJ 209 Instruction Manual

Hf/vhf swr analyzer

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MFJ-209 SWR Analyzer

Table of Contents...................................................................................................... 1

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

Powering The MFJ-209 ............................................................................................ 3

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

Operation Of The MFJ-209....................................................................................... 4

SWR and the MFJ-209 .................................................................................. 4

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

Adjusting Simple Antennas ....................................................................................... 6

Dipoles.......................................................................................................... 6

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

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

Measuring the Feedpoint Resistance of Antennas........................................... 7

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 Tuners....................................................................................................... 10

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

Testing RF Transformers .......................................................................................... 11

Testing Baluns............................................................................................... 11

Measuring Inductance and Capacitance ..................................................................... 12

Measure capacitance...................................................................................... 12

Measure inductance....................................................................................... 12

Resonant Frequency of tuned circuits ........................................................................ 13

Testing RF Chokes........................................................................................ 14

"Zero Beating" the MFJ-209 ..................................................................................... 14

Using the MFJ-209 as a Signal Source ...................................................................... 15

Technical Assistance ................................................................................................. 15

MFJ-209 Parts List ................................................................................................... 15

Instruction Manual

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Summary of Contents for MFJ 209

Page 1: Table Of Contents
Measure capacitance..................12 Measure inductance..................12 Resonant Frequency of tuned circuits ................ 13 Testing RF Chokes..................14 "Zero Beating" the MFJ-209 ..................14 Using the MFJ-209 as a Signal Source ..............15 Technical Assistance ....................15 MFJ-209 Parts List ....................15...
Page 2: Mfj-209 Hf/Vhf Swr Analyzer
50 ohm RF system on frequencies between 1.8 and 170 MHz. In addition the MFJ- 209 can be used as signal source. The MFJ-209 combines three basic circuits; a wide range oscillator, a 50 ohm RF bridge, and a calibrated bridge unbalance indicator. This combination of circuits allows measurement of the SWR (referenced to 50 ohms) of any load connected to the ANTENNA connector.
Page 3: Powering The Mfj-209
MFJ-1312B, is available from MFJ for $12.95. The MFJ-209 has a standard 2.1 mm female receptacle on the top right edge 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.
Page 4: Operation Of The Mfj-209
Instruction Manual OPERATION OF THE MFJ-209 After the MFJ-209 is connected to a proper power source the red on-off button can be depressed to apply power. When pressed, the red button should lock into position. The "ANTENNA" connector (SO-239 type) on the top of the MFJ-209 provides the SWR bridge output connection.
Page 5: Measuring Swr
MFJ-209 SWR Analyzer Instruction Manual The MFJ-209 measures actual SWR. The load must be 50 ohms of pure resistance for a meter reading of 1:1 . The common misconception that 25 ohms of reactance and 25 ohms of resistance in a load will give a 1:1 SWR is absolutely untrue. The actual SWR in this condition will be measured as 2.6:1 .
Page 6: Adjusting Simple Antennas
Tuning basic antennas fed with 50 ohm coaxial cable can be accomplished with the following steps: 1 Connect the feedline to the MFJ-209. 2 Adjust the MFJ-209 until the SWR reaches the lowest reading. 3 Read or measure (with a counter) the MFJ-209's frequency. 4 Divide the measured frequency by the desired frequency.
Page 7: Measuring The Feedpoint Resistance Of Antennas
MFJ-209. A low value non-inductive potentiometer (250 ohms) and a conventional ohm meter can be used to make these measurements. 1 Connect the MFJ-209 directly across the terminals of the unknown impedance. If the load is unbalanced be sure that the ground is connected to the SO-239 "ANTENNA"...
Page 8: Velocity Factor Of Transmission Lines
MFJ-209 SWR Analyzer Instruction Manual Connect the PL-259 to the "ANTENNA" connector of the MFJ-209 and adjust the line or stub by the following method. For critical stubs you may want to gradually trim the stub to frequency. 1 Determine the desired frequency and theoretical length of the line or stub.
Page 9: Impedance Of Transmission Lines
Estimating transmission line loss The loss of 50 ohm feedlines (between 3 and 10 dB) can be measured with the MFJ-209. It is a simple matter to find the loss at a known frequency and then estimate the loss at a lower frequency.
Page 10: Adjusting Tuners
4 Turn off the MFJ-209 and re-connect the transmitter. ADJUSTING AMPLIFIER MATCHING NETWORKS The MFJ-209 can be used to test and adjust RF amplifiers or other matching networks without applying operating voltages. The tubes and other components should be left in position and connected so that stray capacitance is unchanged.
Page 11: Testing Rf Transformers
The 50 ohm winding is connected through a short 50 ohm cable to the "ANTENNA" connector on the MFJ-209. The other winding(s) of the transformer is then terminated with a low inductance resistor that is equal to the winding's impedance. The MFJ-209 can then be swept through the desired transformer frequency range.
Page 12: Measuring Inductance And Capacitance
3. Adjust the tune knob through the bands until you get the lowest SWR. If you do not get a deep meter deflection change to the next inductor with a lower value and try again. Continue the process until you obtain low SWR. Read the resonant frequency off the MFJ- 209 scale or measure it with a counter.
Page 13: Resonant Frequency Of Tuned Circuits
This magnetically couples the MFJ-209 to the resonant circuit. The frequency of the MFJ-209 is adjusted for a dip on the "SWR" meter. The dip occurs at the approximate resonant frequency of the tuned circuit.
Page 14: Zero Beating" The Mfj-209
Refer to the section on measuring the inductance of RF chokes on page 12. "ZERO BEATING" THE MFJ-209 The FREQ. OUT jack of the MFJ-209 supplies enough signal to drive a frequency counter or a receiver. The signal from this jack is strong enough to drive all but the poorest receivers without direct coupling.
Page 15: Using The Mfj-209 As A Signal Source
MFJ-346, to be attatched to the "FREQ. OUT" jack to measure the frequency of the output signal. An attenuator pad or variable resistor can be used to reduce the output level of the MFJ-203. TECHNICAL ASSISTANCE If you have any problem with this unit first check the appropriate section of this manual.
Page 16 MFJ-209 SWR Analyzer Instruction Manual Part Designator Description MFJ Part Number Capacitor, Disc Ceramic, 50v, 20%, 22 pF 200-0018 C2,C3,C4,C6,C7,C8 Capacitor, Disc Ceramic, 25/50v, 20%, .01 uF 200-0004 C10,C33,C36 Capacitor, Disc Ceramic, 25/50v, 20%, .01 uF 200-0004 C11,C13,C14,C16,C19 Capacitor, Disc Ceramic, 25/50v, 20%, .01 uF...
Page 17 Any evidence of alteration, erasure, of forgery shall be cause to void any and all warranty terms immediately. 2. MFJ Enterprises, Inc. agrees to repair or replace at MFJ's option without charge to the original owner any defective product provided the product is returned postage prepaid to MFJ Enterprises, Inc. with a personal check, cashiers check, or money order for $7.00 covering postage and handling.

MFJ 209 Instruction Manual

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