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MFJ-259B Instruction Manual 

HF/VHF SWR Analyzer 

The

 “FREQUENCY COUNTER INPUT”

 connector (BNC type) is for use as a frequency counter only. 

 

Note:

  The following is a description of the opening or default menu used by the MFJ-259B. This unit 

also has an advanced user section in section 4.0. 

3.2 Power-up 

Display 

 
After turning on the 

"POWER"

 switch, or after applying external power with the 

“POWER”

 switch on, a 

sequence of messages appears on the display.  
 
The first message is a program version,

 

 this "VER" number indicates the software version. 

 

 

 
The second message is the software copyright date. 

 

 

 

Note: 

Holding the

 “mode”

 button in continuously before applying power or turning the 

“POWER”

 

switch on, and continuing to hold the 

“MODE”

 button down until the copyright message 

appears, causes a "POWER SAVING OFF" message to appear just as the 

“MODE”

 button is 

released.  This message appears just before the voltage check.  This message confirms the 
battery saving “sleep mode” has been disabled. 

 
The third message is a voltage check. It displays the operating voltage, indicating battery charge or external 
power supply voltage. 

 

 

 
The final power-up display is the “working” display described in 3.2 (Impedance R&X) below. 
 
Two panel meters indicate SWR and Impedance of loads connected to the 

“ANTENNA”

 port. 

 
If you press the 

“MODE”

 button, the mode changes.  After releasing the

 “MODE”

 button, the display will show 

the proper data for the new mode.  The five main (or opening) menu modes are described below. 

3.3 

Main MODE descriptions 

 
If the “

MODE

”  button is momentarily pressed during normal main (or opening) mode operation, the MFJ-259B 

changes display modes.  When the mode first switches, the measurement mode comes up on the screen for a few 
seconds.  The five display modes are described below: 
 

Impedance R&X

 is the initial power-up mode.  In this mode, the MFJ-259B LCD (liquid crystal display, with 

numbers and letters) shows frequency in MHz, SWR, the resistive part of load impedance (R=), and the reactive 
part of load impedance (X=).  The IMPEDANCE meter displays the complex impedance (Z in ohms), and the 
SWR meter displays SWR. 

Summary of Contents for MFJ-259B

Page 1: ...4 3 Coax Loss 11 4 4 Capacitance 11 4 4 Inductance 12 5 0 ADVANCED OPERATION 14 5 1 Forward 14 5 2 General Connection Guidelines 15 5 3 Magnitude of Impedance mode 15 5 4 Return Loss and Reflection Coefficient mode 16 5 5 Distance to Fault mode 16 5 6 Resonance Mode 18 5 7 Percentage Transmitted Power 18 6 0 ADJUSTING SIMPLE ANTENNAS 19 6 1 Dipoles 19 6 2 Verticals 19 6 3 Tuning a simple antenna 1...

Page 2: ...ce meters use broad band voltage detectors The reason virtually all analyzers use broadband detectors is cost Narrow band detectors are very expensive since the detector system would have to use at least one selective gain stable receiver Narrow band detectors would price antenna and impedance analyzers far outside the price range of most casual users Broadband detectors are sensitive to out of ba...

Page 3: ...d bandwidth Antenna tuners SWR bandwidth frequency Amplifiers Input and output matching networks chokes suppressors traps and components Coaxial transmission lines SWR length velocity factor approximate Q and loss resonant frequency and impedance Filters SWR attenuation and frequency range Matching or tuning stubs SWR approximate Q resonant frequency bandwidth impedance Traps Resonant frequency an...

Page 4: ...is 150 mA maximum Be sure you read the battery instructions if you use also install batteries The MFJ 259B has a recessed 2 1 mm power type receptacle near the RF connectors This receptacle is labeled POWER 12VDC The outside conductor of the POWER receptacle is negative the center conductor positive Inserting a power plug in the POWER 12VDC receptacle disables internal batteries as a power source ...

Page 5: ...ls all power supply requirements When using rechargeable batteries the internal black plastic jumper located inside the cover near the external power jack on the back side of the circuit board must be set to the proper position If it is not set to the proper position the batteries will not charge With rechargeable batteries the internal charger jumper located on the printed circuit board near the ...

Page 6: ...hold the MODE button and only release it after the copyright message appears If the Power Saving mode is successfully disabled on power up when the MODE button is released the display will momentarily indicate 3 0 MAIN MENU AND DISPLAY WARNING NEVER APPLY RF OR ANY OTHER EXTERNAL VOLTAGES TO THE ANTENNA PORT OF THIS UNIT THIS UNIT USES ZERO BIAS DETECTOR DIODES THAT MAY BE DAMAGED BY EXTERNAL VOLT...

Page 7: ...ing sleep mode has been disabled The third message is a voltage check It displays the operating voltage indicating battery charge or external power supply voltage The final power up display is the working display described in 3 2 Impedance R X below Two panel meters indicate SWR and Impedance of loads connected to the ANTENNA port If you press the MODE button the mode changes After releasing the M...

Page 8: ...ce in ohms the SWR meter displays SWR Freq Counter is the fifth and final function of the main mode The BNC connector labeled FREQUENCY COUNTER INPUT should connect to the RF sample you want to measure The sensitivity of this port ranges from 10 millivolts at 1 7 MHz to 100 millivolts at 180 MHz The frequency counter is not design for use below 1 MHz The GATE button controls the gate time of the f...

Page 9: ...ystem or device that is not a 50 ohm coaxial system When measuring 50 ohm coaxial systems or antennas interconnecting transmission lines may modify impedance and SWR Use properly constructed 50 ohm coaxial cables of known quality to avoid errors 4 2 Antenna SWR To measure SWR of an antenna or antenna tuner input a If the antenna does not use a dc grounded feed system momentarily short the antenna ...

Page 10: ...1 the likely cause is reactance makes up part or all of the impedance Contrary to popular but very incorrect misconceptions it is impossible to obtain a perfect 1 1 SWR when the load is reactive even if the complex impedance is 50 ohms A good example is a 50 ohm nearly pure reactance load The MFJ 259B LCD will indicate R 0 X 50 while the impedance meter reads 50 ohms The SWR would overflow SWR 25 ...

Page 11: ...asurements the opposite end of the device under test must have an open circuit a short circuit or a pure reactance for termination Any loss resistance will make attenuation appear worse than it actually is To measure loss 1 Connect the MFJ 259B to the 50 ohm cable attenuator or transmission line type balun or transformer you wish to measure Be sure the distant end of the component you are testing ...

Page 12: ...lue will likely change with test frequency This happens because stray inductance in the capacitor and in wires to the ANTENNA connector are in series with the capacitor Effective capacitance does change with frequency and is often quite different from dc or low frequency ac values At higher frequencies the effective capacitance increases reaching infinite capacitance when the capacitor and stray i...

Page 13: ... working circuit 3 Adjust to a frequency as close as possible to the working frequency but one that does not produce a range warning L Z 650 is one warning and L X 7 is another L X 0 indicates the inductor appears as a near perfect short to the MFJ 259B and indicates frequency is too low or the inductor too small to measure When measuring an inductor the displayed inductance value will sometimes c...

Page 14: ...ent SWR return loss impedance reflection coefficient Distance to fault SWR impedance and distance to fault Resonance SWR resistance and reactance Transmit efficiency SWR impedance and forward power as a percentage of apparent power 5 1 Forward In the ADVANCED mode the MFJ 259B measures distance to fault impedance reactance resistance and standing wave ratio SWR It also measures and displays other ...

Page 15: ... for critical information we recommend using books written reviewed and edited by professional engineers 5 2 General Connection Guidelines The ANTENNA connector SO 239 type on the top of the MFJ 259B provides the RF measurement output connection This port is used to measure SWR or perform other RF impedance measurements with the exception of the Frequency Counter mode The ANTENNA connector has abo...

Page 16: ...ault mode The Distance to Fault mode is the third measurement mode in the Advanced mode menu This mode is useful for determining cable length or distance to an open or shorted connection This mode is reached by pressing and releasing the MODE button two times after entering the Advanced mode menu It can also be reached and all other advanced modes by stepping through Advanced modes with the MODE b...

Page 17: ...uencies used to confirm distance the more assurance we have that distances are correct To measure fault distance 1 Select a frequency where the Impedance meter is at the lowest deflection possible and where minimum reactance displayed on the MFJ 259B LCD or where the reactance crosses zero The reactance zero crossing frequency is the frequency where reactance rises when the MFJ 259B is adjusted ei...

Page 18: ...ncy or reactance changes This mode functions like other SWR and impedance modes with the exception the IMPEDANCE meter measures reactance This allows the operator to easily observe frequencies where system reactance crosses zero 5 7 Percentage Transmitted Power Percentage Transmitted Power mode is the final measurement mode available in the Advanced mode menu This mode is reached after entering th...

Page 19: ... common mode currents that are detuning the antenna or the feedline is not a true 50 ohm cable Common mode currents are caused by lack of a balun or other installation errors 6 2 Verticals Verticals are usually unbalanced antennas Many antenna manufacturers incorrectly downplay the need for a good radial system with a grounded vertical With a good ground system the SWR of a directly fed quarter wa...

Page 20: ...al lines can lay in a pile or coil on the floor Internal or external power can be used and the MFJ 259B can be placed on or near large metallic objects with no ill effects Coaxial lines connect normally with the shield grounded When tuning critical stubs gradually trim the stub to frequency Adjust the feedline or stub using the following method 1 Determine the desired frequency and theoretical len...

Page 21: ...ical length of a transmission line To obtain velocity factor you must know the physical length of the line If the distance displayed is 75 feet and the transmission line is actually 49 5 feet long the velocity factor is 49 5 divided by 75 for as result of 0 66 vF Note The far end of the line can be either open circuited or short circuited The line can not be terminated in any impedance other than ...

Page 22: ... not attach any wires other than the feedline to the unit Use the ANTENNA connector s shield for one lead and its center pin for the other Two wire balanced lines must be suspended in a fairly straight line a few feet away from metallic objects or ground Coaxial lines can lay in a pile or coil on the floor Internal or external power can be used and the MFJ 259B can be placed on or near large metal...

Page 23: ...COMMON ROTARY CONTACT OF THE SWITCH TO THE TUNER THE SWITCH MUST CONNECT EITHER THE MFJ 259B OR THE STATION EQUIPMENT TO THE TUNER TRANSMITTING EQUIPMENT MUST NEVER BE CONNECTED TO THE MFJ 259B 1 Connect the MFJ 259B to the tuner input 2 Turn on the MFJ 259B and adjust it to the desired frequency 3 Adjust the tuner until the SWR becomes unity 1 1 4 Turn off the MFJ 259B and re connect the transmit...

Page 24: ...can be measured Transformer efficiency can be measured by comparing the source voltage from the MFJ 259B to the load voltage and using standard power level conversions 7 7 Testing Baluns Baluns can be tested by connecting the 50 ohm unbalanced side to the MFJ 259B ANTENNA connector The balun must be terminated with two equal value load resistors in series The resistor combination must have total r...

Page 25: ...w impedance series resonant frequencies By moving a small insulated screwdriver s blade along the choke you will find a point where the series resonate impedance suddenly changes This is the area that has the highest voltage and the area that adding or subtracting a tiny amount of capacitance will have the largest effect By removing turns to reduce capacitance or adding capacitive stub at this poi...

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