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MFJ-269C-Pro Instruction Manual                                                                       LF/HF/VHF/UHF SWR Analyzer 

20 

                                                           

 

The 

Return Loss and Reflection Coeff 

mode measures and displays 

Return Loss

 in dB along with the 

Voltage Reflection Coefficient

. These measurements are alternative terms that describe SWR. In this 

mode, the analog meters indicate SWR (normalized to 50 Ohms) and Impedance (Z). To use this mode, 
connect the DUT to 

Antenna 

and adjust the VFO for 

Frequency

. Sample display screens are shown 

below: 

                                    

 

                                       

 

 

5.4.1.5 Resonance 

 
To access 

Resonance Mode, 

enter Advanced-1 and then press

 Mode

 twice. If already in Advanced-1, 

scroll to it using the 

Mode 

switch. The entry screen is shown below: 

                                                          

 

Resonance Mode 

draws attention to reactance, displaying it on the

 Impedance 

meter as an analog tuning 

aid for identifying resonance. In this mode, the MFJ-269C measures and displays 

Frequency

, 

SWR

, 

Resistance (

Rs

), and Reactance (

Xs

).  When reactance equals 

zero 

in a system that has selectivity, the 

system 

is said to be 

resonant

. 

                                       

 

Note:  

Because of transmission line effects, zero-reactance (or resonance) can occur on frequencies where 

the antenna is

 

not 

actually resonant. Conversely, an antenna may 

appear

 to contain reactance even at its 

true resonant frequency when it is measured through a feedline. A less-than-perfectly matched antenna 
and feedline, when used with a feedline that is not an exact multiple of 1/4 wavelength (0, 1/4, 1/2, 3/4, 
etc.), will have reactance added by the feedline. Reactance added by a non-quarter wave multiple 
mismatched feedline may coincidentally cancel a non-resonant antenna’s reactance, making the system 
resonant. 
 
The SWR of the system, if the feedline is a true 50-ohm feedline (or any impedance feedline that matches 
the normalized (Zo) impedance setting of the instrument) with minimal loss and free from common mode 
currents, will not change as the feedline length is changed. This is true even if the resonant frequency or 
reactance changes.  
 

Resonance Mode

 functions like other SWR and impedance modes, with the exception the 

Impedance 

meter measures only reactance. This allows the operator to easily locate frequencies where system 
reactance crosses zero. 
 

5.4.1.6 Match 

Efficiency 

 

Summary of Contents for MFJ-269CPro

Page 1: ...UTION 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 2014 MFJ ENTERPRISES INC C Model MFJ 269CPro VERSION 1A ...

Page 2: ...POWER SAVING 6 3 0 MAIN MENU AND DISPLAY 7 3 1 GENERAL CONNECTIONS 7 3 2 POWER UP DISPLAY 7 3 3 MAIN MEASUREMENT MODES LF HF VHF 0 53 230 MHZ 8 3 4 FREQUENCY CONTROL 9 4 0 MAIN OR OPENING MODE 10 4 1 GENERAL CONNECTIONS 10 4 2 ANTENNA SWR AND IMPEDANCE 10 4 3 COAX LOSS FUNCTION 2 12 4 4 CAPACITANCE FUNCTION 3 13 4 5 INDUCTANCE FUNCTION 4 14 4 6 FREQUENCY COUNTER FUNCTION 5 15 5 0 ADVANCED OPERATIO...

Page 3: ...31 7 0 TESTING AND TUNING STUBS AND TRANSMISSION LINES 31 7 1 TESTING STUBS 31 7 2 VELOCITY FACTOR OF TRANSMISSION LINES 32 7 3 IMPEDANCE OF TRANSMISSION LINES OR BEVERAGE ANTENNAS 33 7 4 ADJUSTING TUNERS 34 7 5 ADJUSTING AMPLIFIER MATCHING NETWORKS 35 7 6 TESTING RF TRANSFORMERS 35 7 7 TESTING BALUNS 35 7 8 TESTING RF CHOKES 36 8 0 TECHNICAL ASSISTANCE 37 ...

Page 4: ...lso functions as a non precision signal source and frequency counter Operating frequency extends from 0 53 to 230 MHz in nine overlapping bands with extended SWR measurement from 415 to 520 MHz LF coverage may be adjusted to cover 0 470 kHz 1 1 Typical Use The MFJ 269C Pro may be used to adjust test or measure the following Antennas SWR impedance reactance resistance resonant frequency and bandwid...

Page 5: ...acy Building these sophisticated detectors into the MFJ 269C or any small handheld unit would drive the price far beyond the reach of most hobbyists As an alternative we use broadband detectors that provide accurate measurements at a much lower cost The only drawback is that broadband detectors can be sensitive to powerful out of band signals Most of the time out of band interference isn t an issu...

Page 6: ...ine Note Some handheld analyzers display erroneous readings falling outside the reliable measurement range presenting that data numerically as if it were factual The MFJ 269C Pro is designed to avoid such errors by displaying an on screen warning Z 1500 anytime data falls outside the unit s accurate measurement range 2 0 POWER SOURCES This section describes power supply and battery selection READ ...

Page 7: ...emove all eight screws on the sides of the case and remove the back cover The black plastic jumper fits over two of three adjacent pins see detailed instructions below The plug must be properly positioned for the type of cell you plan to use AA rechargeable or AA non rechargeable 2 3 Rechargeable Batteries Important Note When using rechargeable batteries your external power source must deliver at ...

Page 8: ...ed Pressing Mode during a low voltage warning will disable the on screen alert and allow you to continue operating However measurements may not be reliable when operating the analyzer with insufficient supply voltage 2 6 Sleep Mode Power Saving Typical current drain for the MFJ 269C Pro is around 150 mA for HF operation 250 mA for UHF Battery operating time is by default extended significantly thr...

Page 9: ...ary RF measurement connection It is used for all functions except frequency counter measurements The Power connector 2 1 mm is described in section 2 0 Please read the power source section carefully before attempting to operate the analyzer Improper voltage application the wrong battery charger setting or reversed polarity could permanently damage your unit The BNC Frequency Counter Input is for f...

Page 10: ...mode and it is the function most commonly used The top line of the data screen displays Frequency in MHz and SWR while the bottom line shows complex impedance where Rs equals the load s series resistive component and Xs shows the load s series reactive component In this function the analog SWR and Impedance Meters Z are also activeated 2 Coax Loss Pressing Mode once brings up the Coax Loss followe...

Page 11: ... each band edge to ensure gap free tuning across the spectrum Note that LF coverage may be lowered to 0 470 0 940 MHz or lower for 600 Meters and select maritime services To modify 1 adjust Tune fully counter clockwise 2 remove the back cover 3 Remove battery pack by removing Philips head screws and 4 using a 2 mm hex tuning wand readjust inductor L12 while watching the frequency display 2 UHF Ope...

Page 12: ... practical guidelines 1 Connectors If connector transitions RF adapters are needed use only high quality parts and check them for wear oxidation dirt and tight pin contact before proceeding 2 Lead Length Make all connection electrically secure and keep all leads as short as possible This precaution is especially important when measuring electrical components that are not part of a 50 ohm coaxial s...

Page 13: ...strong working knowledge of RF systems you may find these added modes of limited value Most represent more technically sophisticated ways of expressing the same data offered by the basic modes Antenna hints 1 Measuring Antenna Impedance For complex impedance measurements always install the analyzer as close as possible to the element s feedpoint within or 1 2 degrees of phase shift Alternatively y...

Page 14: ... look for a feed problem Here are some possibilities to check 6 Common Mode Current Your coax may be carrying Common Mode Current on its outer shield and radiating RF To eliminate this problem install a Guanella current balun at the feedpoint It will isolate the outer coax shield from the radiating portion of the antenna stabilize your SWR reduce receiver noise and suppress RF in the shack Install...

Page 15: ...e loss The loss in dB will be displayed for any specific frequency you select between 0 53 and 230 MHz 4 4 Capacitance Function 3 Access the capacitance mode by stepping to the Capacitance screen using the Mode switch The top line of the working display shows the Frequency in MHz and the Capacitive Reactance Xc of the DUT at that specific frequency The lower line displays the computed Capacitance ...

Page 16: ...ometimes intentionally operated at or near this frequency but for most applications the frequencies will be far below it In addition to the display the analyzer s Impedance meter displays the reactance X in ohms of the capacitor 4 5 Inductance Function 4 Access the Inductance mode by stepping the Mode switch to the Inductance identification screen The top line of the working display shows the Freq...

Page 17: ...pen circuit or a trap with infinite reactance At some very low frequency it may look like a short 4 6 Frequency Counter Function 5 The Frequency Counter mode is the final Main Mode function To access the counter from the opening menu press Mode four times or if already in the Main menu step through it until the Freq Counter screen appears Important Note Never apply dc or more than 5 volts peak to ...

Page 18: ... resistance reactance SWR and complex impedance In some modes the system cross checks itself and displays a weighted average of the most accurate measurement methods or searches for certain impedance conditions System resolution is limited mostly by diode linearity calibration stability and external noise or signals While we have attempted to make this unit as accurate as possible most formulas co...

Page 19: ...olated from the load external voltages will couple directly into internal detectors WARNING NEVER APPLY EXTERNAL VOLTAGES OR RF SIGNALS TO THE ANTENNA CONNECTOR ALSO PROTECT THIS PORT FROM ESD Use proper RF connections Keep leads as short as possible when measuring components or non matched systems Interconnecting transmission lines or wires can modify readings including impedance and SWR Use prop...

Page 20: ... way of expressing R and X Instead of providing R and X as separate numerical quantities it presents a vector type description of measured impedance Impedance Z is still described as the length magnitude of a line representing the complex impedance this is the same Z as given in other functions Besides Z an angle between zero and 90 degrees is shown This angle represents the phase difference betwe...

Page 21: ...llel Equivalent Impedance of Rp 126 Xp 102 ohms You can make the conversion in this mode by pressing the Gate button see section 5 4 1 3 below 5 4 1 3 Parallel Equivalent Impedance Pressing the Gate button twice from the Magnitude and Phase of Load Impedance mode toggles the analyzer into a parallel equivalent impedance sub mode Parallel equivalent display examples 7 1598 MHz 3 2 Rs 126 Xs 102 14 ...

Page 22: ... of transmission line effects zero reactance or resonance can occur on frequencies where the antenna is not actually resonant Conversely an antenna may appear to contain reactance even at its true resonant frequency when it is measured through a feedline A less than perfectly matched antenna and feedline when used with a feedline that is not an exact multiple of 1 4 wavelength 0 1 4 1 2 3 4 etc wi...

Page 23: ... input of the feedline or system where the measurement is made It is mostly useful in laboratory situations It does not describe antenna system or feedline efficiency Even with nearly zero percent match efficiency an antenna system can radiate the applied power with good efficiency In fact for any given amount of match efficiency your antenna system could be near 100 or near zero percent efficient...

Page 24: ...SWR normalized to 50 Ohms and the impedance meter is disabled To use this mode connect the DUT to the Antenna connector adjust Frequency as needed and read the results on the screen and SWR analog meter display 5 4 2 2 Match Efficiency UHF Match Efficiency is the second and final measurement available in the Advanced 1 UHF menu To access it first enter the Advanced 1 menu then press and release Mo...

Page 25: ...alculations aren t available at UHF frequencies because the internal capacitance of the diodes and lead lengths through the connector and connections create errors in other measurements Only SWR and SWR related functions are displayed for the UHF band 5 5 1 Distance to Fault DTF for HF VHF only With Vf entered in the previous function the next function in the display menu is Distance to Fault in F...

Page 26: ...ansmission line To determine antenna length treat the antenna like a transmission line following the procedure for measuring Distance To Fault For a dipole your result will be the electrical length of one leg For a longwire or Beverage it will be electrical length for the entire antenna 5 5 1 4 DTF Measurement Procedures Distance to Fault is the first measurement mode in Advanced 2 To enter the mo...

Page 27: ...Physical Distance in Feet to a transmission line fault or mis termination To obtain the true physical distance the analyzer multiplies Electrical Distance by the feedline Vf entered in step 1 This reading will only be as accurate as the velocity factor you entered To find the Electrical Length in Feet you must program the velocity factor as Vf 1 00 in step 1 5 After determining the DTF press Mode ...

Page 28: ...tells you length of a line in electrical degrees when you know a the physical length and b the velocity factor You can also measure the electrical length directly using the Distance to Fault mode sec 5 5 This mode is useful for calculating the Length in Degrees for matching sections and phasing lines If you enter this mode after using Distance to Fault sec 5 5 the Vf and Length will be programmed ...

Page 29: ...ess the Gate To decrease line length press Mode When the desired length appears simultaneously press and hold Gate and Mode to lock it in The display will now change to Line length l 67 2 ft 7 Pressing Mode switches the display to Length in Feet for the degrees programmed in at the selected Vf 5 5 3 2 Line Length in Feet This mode displays the length in feet required to obtain a certain number of ...

Page 30: ...ill appear Note If you know the true electrical length in degrees set velocity factor to VF 1 0 and enter the electrical length in degrees as indicated in step 5 3 Press and release the Mode button The display will flash Line Length in Degrees After a moment the display changes to sample screen 4 Press Mode again The Line Length in Feet screen appears 5 It then quickly changes to the data screen s...

Page 31: ...hange reference impedance in this mode It continues to display the 50 ohm normalized value Only the display SWR changes 5 6 1 Z Characteristic After entering Advanced 3 the display changes to a default setting of Zo 75 It also prompts the operator to enter a different value Z Characteristic 1 Zo may be re set using Gate to increase or Mode to decrease the normalized impedance value 2 After selecti...

Page 32: ...de for an extended period to cycle the analyzer back to the Main or to another Advanced mode 6 0 ADJUSTING SIMPLE ANTENNAS Most antennas are adjusted by varying element length and most homemade antennas are simple verticals or dipoles that are easily adjusted 6 1 Dipoles Since a dipole is a balanced antenna it is a good idea and good engineering practice to put a balun at the feedpoint The balun c...

Page 33: ...ven a good ground system the SWR of a directly fed quarter wave vertical can be nearly 2 1 SWR often improves if the ground system is poor but performance suffers Low SWR on a directly fed Marconi might be a sign of inefficiency Verticals are tuned the same way as dipoles lengthening moves the frequency lower and shortening moves the frequency higher 6 3 Tuning a simple antenna Select any mode tha...

Page 34: ...ritical stubs gradually trim the stub to frequency and adjust the feedline or stub using the following method 1 Determine the operating frequency and calculate the theoretical length for the feedline or stub 2 Cut the stub or feedline 20 longer than the calculated length 3a Quarter Wave Measure frequency of the lowest resistance and reactance or the lowest impedance for odd quarter wave stubs To f...

Page 35: ...ve apart If measured distances agree they are almost certainly very reliable Use the following method 1 Using procedures in 5 5 Advanced 2 measure distance to fault with Vf set at 1 00 2 Measure the Physical Length of the line in feet 3 Divide the measured Physical Length by the display reading Example 27 feet actual physical length divided by 33 7 feet measured electrical length equals 80 The vel...

Page 36: ...ency and note only the SWR change 3 Adjust the termination resistance until the SWR remains as constant as possible with very large frequency changes around the operating frequency range 4 The resistance of the termination resistor is the surge impedance of the system The electrical length of the Beverage can be determined by using procedures outlined in Advanced 2 7 4 Adjusting Tuners The MFJ 269...

Page 37: ...condition with the low level of RF from the MFJ 269C Pro 7 6 Testing RF Transformers RF transformers designed to operate with 10 1000 ohm termination on one of the windings can be tested with the MFJ 269C Pro The 10 to 1000 ohm winding is connected through very short less than one electrical degree long leads to the Antenna connector on the MFJ 269C Pro The other winding s of the transformer is te...

Page 38: ...where the distributed capacitance and inductance form a low impedance series resonance This series resonance occurs because the choke acts like a series of back to back L networks This causes three problems 1 Impedance from end to end in the choke becomes very low 2 The voltage at the center of the resonant point becomes very high often causing severe arcing 3 The current in the winding becomes ve...

Page 39: ...ty of the warranty claim and submit the original or machine reproduction of such proof of purchase to MFJ Enterprises Inc at the time of warranty service MFJ Enterprises Inc shall have the discretion to deny warranty without dated proof of purchase 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 r...

Page 40: ...rises Inc reserves the right to make changes or improvements in design or manufacture without incurring any obligation to install such changes upon any of the products previously manufactured 11 All MFJ products to be serviced in warranty or out of warranty should be addressed to MFJ Enterprises Inc 300 Industrial Park Rd Starkville Mississippi 39759 USA and must be accompanied by a letter describ...

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