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MFJ-969 DELUXE Versa Tuner II 

MFJ-969 Versa Tuner II 

Instruction Manual 

 

General Information 

 
The MFJ-969 is a 300 watt RF output power antenna tuner that will match any transmitter 
or transceiver to virtually any antenna.  Peak or average forward and reflected power and 
SWR can be read on the illuminated cross-needle meter. 
 
The MFJ-969 uses a "T" matching network and covers all bands between 160 and 6 meters.  
This network will tune dipoles, inverted-vees, verticals, mobile whips, beams, random 
wires, and many other antennas.  The MFJ-969 has rear panel connectors for coaxial, single 
wire or two wire feedlines.  A built-in 4:1 balun allows the use of balanced open wire, 
twinlead, or twin-axial feedlines. 
 
An internal eight position antenna-selector switch selects a built-in 50 ohm dummy load, 
two separate coaxial line outputs, or a single wire line-balanced line output.  All of these 
functions can be selected in tuned (with tuner's "T" network in line) or bypassed (no tuning 
circuit) configurations. 

Peak Reading SWR/Wattmeter 

 
The illuminated cross-needle meter measures the peak or average FORWARD power, 
REFLECTED power, and SWR.  The wattmeter is active in all ANTENNA SELECTOR 
positions.  To use the wattmeter without using the MFJ-969 tuning circuits select one of 
the ANTENNA SELECTOR positions under BYPASS. 
 

NOTE: 

The meter ON/OFF switch must be ON for the meter circuit to function.  The 
MFJ-969 wattmeter circuit does not function accurately if the Auto Tuner in 
your radio is used.  To disable the meter, turn the meter ON/OFF switch to the 
OFF position.  Set the ANTENNA SELECTOR switch to one of the bypass 
positions when using the Auto Tuner in your radio. 

 
Peak envelope power (PEP) is measured when the PEAK or AVERAGE METER push 
button (right-hand side) in placed in the PEAK (in) position.  Peak power and average 
power values are equal with steady unmodulated carriers, FSK, or FM.  The PEP power is 
twice the average power with SSB two tone test modulation. PEP power may be any 
amount larger than the average power with SSB voice signals. 
 
The metering circuit in this unit provides very accurate forward peak power readings 
during with any form of modulation.  Either an internal 9 volt battery for portable 
operation, or an external supply can be used to power the peak detector. Current demand is 
very low, and the 9 volt battery will last its' shelf life.  
 

Summary of Contents for -969 DELUXE Versa Tuner II

Page 1: ...k or average FORWARD power REFLECTED power and SWR The wattmeter is active in all ANTENNA SELECTOR positions To use the wattmeter without using the MFJ 969 tuning circuits select one of the ANTENNA SELECTOR positions under BYPASS NOTE The meter ON OFF switch must be ON for the meter circuit to function The MFJ 969 wattmeter circuit does not function accurately if the Auto Tuner in your radio is us...

Page 2: ...ale when the 30W power sensitivity is selected This scale has a picket every 5 watts above 10 watts and at each watt below 10 watts The reflected scale is also divided by 10 when using the 30W switch position When trying to measure power with a less than perfect match the reflected power should be subtracted from the forward power readings The SWR is read directly from eleven red SWR curves that r...

Page 3: ...ators can operate with high RF voltages These voltages may cause serious RF burns These high RF voltages may also damage anything contacting or within a half inch of the terminals 3 Install the MFJ 969 between the transmitter and antenna Use a 50 ohm coaxial cable to connect the transmitter or transceiver to the SO 239 UHF female labeled TRANSMITTER on the back of the tuner 4 Coaxial feedlines att...

Page 4: ...rt in the tuning instructions shows typical ROLLER INDUCTOR settings for each amateur band NOTE If your transmitter uses an adjustable output circuit it must be properly tuned into a 50 ohm load at the operating frequency Proper tuning can be accomplished by placing the ANTENNA SELECTOR switch in the fully clockwise BYPASS DUMMY LOAD position Adjust the transmitter according to the manufacturer s ...

Page 5: ... 7 15 4 1 2 4 1 2 107 10 15 6 6 112 14 15 6 1 2 6 1 2 116 18 2 7 7 118 21 1 8 8 119 24 9 8 1 2 8 1 2 119 28 5 9 9 121 50 2 9 1 2 9 1 2 123 3 Apply just enough power on CW or AM FM RTTY to obtain noticeable deflection on the reflected power meter 4 Carefully adjust the ROLLER INDUCTOR and ANTENNA controls for the lowest reflected power NOTE These controls interact Adjust the ROLLER INDUCTOR for min...

Page 6: ... you are using enough inductance a higher ROLLER INDUCTOR number and have the capacitors open far enough a higher front panel number If this tuner arcs at the rated power levels please double check all connections and follow the tuning procedures again Be sure you are using the largest amount of capacitance and lowest amount of inductance lowest ROLLER INDUCTOR TRANSMITTER and ANTENNA numerical se...

Page 7: ... the use of woven or braided conductors in RF and lightning grounds unless the lead needs to be flexible Antenna Hints WARNING For operator safety a good outside earth ground or water pipe ground should ALWAYS be installed and connected to the case of the MFJ 969 Make certain the safety ground also connects to the transmitter and other station accessories A wing nut post marked GROUND is provided ...

Page 8: ...i band antenna add or subtract 1 8 wave of feedline for the band that won t tune and try again 4 Never try to load a G5RV or center fed dipole on a band below the half wave design frequency If you want to operate an 80 meter antenna on 160 meters feed either or both conductors as a longwire against the station ground To avoid problems matching or feeding any dipole antenna with high impedance line...

Page 9: ... 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 also send questions by mail to MFJ Enterprises Inc 300 Industrial Park Road Starkville MS 39759 by Facsimile FAX to 662 323 6551 or by email to techinfo mfjenterprises com Send a complete description of your prob...

Page 10: ...MFJ 969 DELUXE Versa Tuner II 10 Schematic ...

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