MFJ Enterprises MFJ-249D Instruction Manual Download | Manualshive

Page: 1 / 16

background image

1
2
3
...
»

Summary of Contents for MFJ-249D

Page 1: ......

Page 2: ...s 5 3 4 Blinking VOLTAGE LOW display warning 6 4 0 MAIN OR OPENING MODE 6 4 1 General Connection Guidelines 6 5 0 ADJUSTING SIMPLE ANTENNAS 7 5 1 Dipoles 7 5 2 Verticals 7 5 3 Tuning a simple antenna 7 6 0 TESTING AND TUNING STUBS AND TRANSMISSION LINES 8 6 1 Testing Stubs 8 6 2 Velocity Factor of Transmission Lines 8 6 3 Impedance of Transmission Lines or Beverage antennas 8 6 4 Adjusting Tuners ...

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: ...28 to 230 MHz using a precision reduction drive VFO tuning capacitor and two band switches Bands of coverage are Main Switch 155 230 MHz 113 155 MHz 67 113 MHz 28 67 MHz 11 28 MHz Lower Range Lower Range Switch 4 7 11 MHz 2 1 4 7 MHz 1 0 2 1 MHz 0 52 1 0 MHz 0 28 0 52 0 10 0 16 2 0 POWER SOURCES Please read this entire section before connecting your analyzer to any power source Improper connection...

Page 5: ...low the charger will not work properly and batteries will eventually discharge We recommend charging batteries with the MFJ 249D power switch off and allowing enough charging time to establish full battery charge A minimum of ten hours is recommended When using rechargeable batteries your power source must deliver a minimum of 13 8 volts to meet the minimum charge voltage threshold Typical chargin...

Page 6: ...ppears on the screen 4 Release Mode If Sleep Mode was disabled successfully the message shown below will appear on screen The Sleep Mode function becomes re enabled anytime the analyzer is turned Off and On again 3 0 MAIN MENU AND DISPLAY IMPORTANT WARNING Never Apply RF or any other external voltage to the Antenna port of this unit The MFJ 249D uses zero bias detector diodes that may be damaged b...

Page 7: ...erical and a bar graph format The maximum numerical SWR displayed is 25 Any SWR adjustments have to be made at the antenna since any adjustments at the transmitter end of the feedline cannot affect the losses nor the efficiency of the antenna system 2 Impedance Magnitude This mode will provide magnitude of the impedance readings for the load connected to the ANTENNA jack The readings are the combi...

Page 8: ...his unit uses zero bias detector diodes that are easily damaged by external voltages over a few volts Also confirm the power supply is correct as described in Section 2 0 before operating this unit A basic understanding of antenna theory and transmission line behavior will be helpful for making the best use of the data provided by your MFJ 249D The ARRL Handbook and ARRL Antenna Book provide conci...

Page 9: ...un has been installed at the feed point to choke it off Common mode induction currents may also result from other installation errors such as running the feedline parallel rather than perpendicular to the radiating element Repositioning the feedline may reduce unwanted inductive coupling 5 2 Verticals Verticals in the monopole class require a ground plane To simplify installation and cut costs man...

Page 10: ...enter pin of the connector Coaxial lines can lay in a pile or coil on the floor two wire lines must be suspended in a straight line a few feet away from metallic objects or ground The lines must be open circuited at the far end for odd multiples of 1 4 wave stubs i e 1 4 3 4 1 1 4 etc and short circuited for half wave stub multiples like 1 1 1 2 etc Connect the PL 259 to the ANTENNA connector of t...

Page 11: ...e 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 6 4 Adjusting Tuners The MFJ 249D can be used to adjust tuners Connect the MFJ 249D ANTENNA connector to the t...

Page 12: ...pability and lowest loss for given materials To evaluate the balun DUT measure SWR while connecting the grounded clip lead to point A B and C When functioning properly a current balun will exhibit low SWR over its entire operating range with the clip lead installed at any of those three positions A well designed voltage balun should show low SWR over its operating range with the clip lead installe...

Page 13: ...ot get a low SWR change to the next smaller value standard capacitor and try again Repeat the process until you get low SWR 4 Solve this equation using F as the resonant frequency and C as the capacitance of the standard capacitor L H 1 00003948F C F MHz C pF 2 µ 6 9 Resonant Frequency of Tuned Circuits The MFJ 249D can be used to measure the resonant frequency of tuned circuits by two methods The...

Page 14: ...er will identify the low impedance series resonant frequencies 1N34 01 10K Measure the voltage between these points with a Hi Z meter All leads should be short choke ANTENNA To the MFJ 249B s connector Refer to the section on measuring the inductance of RF chokes 7 0 TECHNICAL ASSISTANCE If you have any problem with your MFJ 249D first check the appropriate section of this manual If the manual doe...

Page 15: ...e the original parts you wish to replace your proof of purchase and a personal check cashiers check or money order must be provided to cover postage and handling Postage and handling may vary according to the weight of the product in question We also take MasterCard Visa American Express and Discover credit cards 4 This warranty is NOT void for owners who attempt to repair defective units Technica...

Page 16: ...MFJ 989C VersaTuner V Instruction Manual 14 ...

Reviews:

No comments

Related manuals for MFJ-249D

Brand: BANTE inststruments Pages: 15

Brand: 3Bays Pages: 21

Brand: MADDALENA Pages: 4

Brand: Macnaught Pages: 4

Brand: Magnum Energy Pages: 3

Kotron 805 series

Brand: Magnetrol Pages: 36

Brand: Magnescale Pages: 104

Brand: Magnescale Pages: 44

Brand: National Instruments Pages: 85

Brand: National Instruments Pages: 12

Brand: National Instruments Pages: 18

Brand: National Instruments Pages: 12

Brand: Ralston Instruments Pages: 52

Brand: Vaisala Pages: 2

WJ-NU301K Series

Brand: i-PRO Pages: 24

WJ-NU101K Series

Brand: i-PRO Pages: 18

Brand: janitza Pages: 48

HF scientific AccUView LED

Brand: Watts Pages: 40

Brands by name

0 1 2 3 4 5 6 7 8 9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Popular brands

Load more brands