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INSTRUCTION  MANUAL

CAUTION:  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      2013  MFJ  ENTERPRISES,  INC.

C

Model  MFJ-259C

VERSION  C1

HF/VHF  SWR  Analyzer

 

 

Summary of Contents for MFJ-259C

Page 1: ...d 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 2013 MFJ ENTERPRISES INC C Model MFJ 259C VERSION C1 HF VHF SWR Analyzer ...

Page 2: ...lines 7 4 2 Antenna SWR 7 4 3 Coax Loss 9 4 4 Capacitance 9 4 5 Inductance 10 5 0 ADVANCED OPERATION 11 5 1 Forward 11 5 2 General Connection Guidelines 12 5 3 Magnitude of Impedance mode 12 5 4 Return Loss and Reflection Coefficient mode 13 5 5 Distance to Fault mode 13 5 6 Resonance Mode 14 5 7 Percentage Transmitted Power 14 6 0 ADJUSTING SIMPLE ANTENNAS 14 6 1 Dipoles 14 6 2 Verticals 15 6 3 T...

Page 3: ...eeded to deliver the additional RF power greatly reduces battery life In fact over 70 of the analyzer s 150 mA current drain is already allocated to the VFO and its amplifier stages for generating a low harmonic level amplitude test signal Most RF interference problems occur at lower frequencies and are caused by high power AM broadcast stations These signals couple efficiently into large antenna ...

Page 4: ...stance or R ohms SWR referenced to 50 ohms The MFJ 259C as a non precision signal source VFO output is leveled at approximately 3 Vpp or around 20 milliwatts into a 50 ohm load This signal is relatively pure with harmonics better than 25 dBc dB below the fundamental frequency carrier The internal source impedance Zo is 50 ohms A more complete description of the MFJ 259C s features along with prope...

Page 5: ... of the Charger Jumper To gain access remove the eight screws securing the analyzer s back cover and separate it from the unit Look for a 3 pin header with a small black plastic shorting plug that fits over two of its pins It is located at the top of the main pc board near the OFF ON switch and power connector The shorting plug must be properly positioned for the type of battery you intend to use ...

Page 6: ... minute inactivity window During any 2 minute period you must actuate the Mode switch or adjust the frequency by more than 50 kHz at least once for the analyzer to remain awake Any time a two minute inactivity period elapses the power saving circuit automatically switches in When the analyzer goes to sleep a blinking SLP message will appear in the display s lower right corner as shown below To rea...

Page 7: ...ion The five main modes and their opening screens are described in Section 3 3 below 3 3 Main MODE descriptions Press the Mode switch to scroll through the analyzer s five operating modes By scrolling we mean that each tap of the mode switch will step the analyzer ahead to the next menu selection Each new selection comes up on the display with an Identifier Screen After 3 seconds the Identifier Sc...

Page 8: ... XL at the VFO frequency in ohms The lower line shows the measured inductance L in microhenries µH The Impedance meter displays reactance in ohms 5 Frequency Counter The fifth mode converts the analyzer into a discrete frequency counter Connect the RF source DUT to the BNC connector labeled Frequency Counter Input As with many counters the sensitivity threshold for a locked in reading gradually de...

Page 9: ... X or Z remember that any length of transmission line you install between the load and the analyzer will displace the load from the analyzer s calibration plane For simple handheld analyzers like the MFJ 259C the calibration plane is always located at the analyzer s RF connector This is the point where Zo 50 Ohms and Phase shift 0 degrees It is the only test point where the analyzer will be calibr...

Page 10: ...cy By the same token if you adjust your antenna for an Impedance reading of 50 ohms the load could have a substantial reactive component e g R 46 X 17 that elevates SWR and shifts the minimum SWR point to a different frequency SWR is always your best predictor of antenna performance 4 Tuning and Matching Unlike simple wire dipoles many antennas such as Yagis and verticals are adjustable for both r...

Page 11: ...t to the Antenna connector Confirm the distant end of the DUT isn t terminated by a resistance 2 Turn the analyzer ON and toggle the Mode switch once to the Coax Loss Screen 3 Tune the analyzer s VFO to the frequency where you wish to measure loss The loss in dB will be displayed for any specific frequency you select between 0 53 and 230 MHz 4 4 Capacitance Access the Capacitance Mode by stepping ...

Page 12: ...e switch to the Inductance identification screen The top line of the working display shows the VFO Frequency in MHz and the Inductive Reactance XL of the DUT at that particular frequency The lower line shows the Inductance in uH Inductance is calculated using the measured Reactance XL and the VFO frequency The MFJ 259C will become inaccurate when measuring reactance below 7 ohms or above 650 ohms ...

Page 13: ...s and hold the Gate and Mode buttons simultaneously for several seconds When you release the Advanced message appears on screen The Advanced Menu features the following modes Impedance SWR impedance magnitude phase angle of impedance Return Loss and Reflection Coefficient SWR return loss impedance reflection coefficient Distance to fault SWR impedance and distance to fault Resonance SWR resistance...

Page 14: ... source resistance The unterminated open circuit voltage increases to approximately 1 volt RMS Harmonics are better than 25 dBc over the VFO operating range While the VFO is not frequency stabilized it is useful as a discrete signal source for many applications Also note that the Antenna connector is not dc isolated from the load so any external bias voltage will couple directly to the internal de...

Page 15: ...nce to the transmission line s abnormality To obtain the physical distance multiply electrical distance times the feed line s specified Velocity Factor Vf For example if the analyzer display reads DTF 75 feet and the transmission line is typical RG 8 with a specified velocity factor of 0 66 the physical distance to the fault will be 75 x 66 49 5 feet An open or a short circuit at the fault yields ...

Page 16: ...o 0 degrees of phase rotation as possible 5 7 Percentage Transmitted Power From the Advanced screen toggle the Mode button four times to open Percentage of Transmitted Power This parameter is yet another way of representing the basic SWR measurement see chart at 5 1 Mathematically it is an inverse presentation of the Percentage of Reflected Power scale If your load measures 3 1 1 SWR the Percentag...

Page 17: ...dings Far better to install the best ground system possible and configure a matching network at the base of the vertical element to match into a 50 ohm feed system Verticals tune the same as dipoles add length to lower the operating frequency and shorten to raise it Another class of verticals are considered ground independent because they come with a counterpoise or rigid radial system built into ...

Page 18: ...gth Continuing 5 Divide the present frequency by the desired frequency to calculate a Scaling Factor 6 Multiply the Scaling Factor by the feed line s present physical length to find the desired physical length 7 Cut the stub and confirm that the reactance null X 0 is on the desired frequency 7 2 Velocity Factor of Transmission Lines To determine the Velocity Factor Vf of a transmission line select...

Page 19: ...ion access by pressing and holding the Gate switch Methodology When random length transmission line is terminated by a load of the same impedance no transformation occurs between the cable s near end and far end However as soon as a mismatch is introduced at one end the impedance transforms to a value higher or lower than the line s characteristic impedance at the opposite end If viewed on a Smith...

Page 20: ...stance decade box 3 Adjust the analyzer s VFO frequency and note only the SWR change SWR need not be low 4 Adjust termination resistance until SWR remains constant over the widest possible range 5 The resistance of the termination resistor is the line impedance or surge impedance of the system 7 4 Adjusting Tuners Use a short patch cable to connect the analyzer s Antenna jack to the tuner s 50 ohm...

Page 21: ...e the basic SWR Resistance R Reactance X Mode plus the Impedance Magnitude Z option to evaluate the DUT s impedance and useable bandwidth You may also measure the transformer s efficiency by comparing the source voltage generated by the MFJ 259C to the load voltage using standard power level conversions 7 7 Testing Baluns To test balun performance connect the analyzer Antenna jack to the balun s 5...

Page 22: ...along the choke to find a point where the series resonate impedance changes suddenly This is the region that has the highest voltage present and the area where adding or subtracting even a tiny amount of capacitance had the greatest effect To shift the resonance out of the desired frequency range try removing turns to reduce capacitance or adding a capacitive stub A small change in capacitance has...

Page 23: ...s warranty is NOT void for owners who attempt to repair defective units Technical consultation is available by calling 662 323 5869 5 This warranty does not apply to kits sold by or manufactured by MFJ Enterprises Inc 6 Wired and tested PC board products are covered by this warranty provided only the wired and tested PC board product is returned Wired and tested PC boards installed in the owner s ...

Page 24: ...MFJ 259C Manual Version C1 Printed In U S A 300 Industrial Park Road Starkville MS 39759 MFJ ENTERPRISES INC ...

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