MFJ MFJ-266C User manual
INSTRUCTION MANUAL
CAUTION: Read All Instructions Before Operating Equipment
MFJ ENTERPRISES, INC.
300 Industrial ark Road
Starkville, MS 39759 USA
Tel: 662-323-5869 Fax: 662-323-6551
COP YRI GHT 20 12 MF J E NTE RPRI S ES, INC.
C
Model MFJ-266C
VERSION 2A
MFJ-266C HF/VHF/UHF Antenna Analyzer Instruction Manual
Version 2A ii 2012 MFJ Enterprises, Inc
DISCLAIMER
Information in this manual is designed for user purposes only and is not
intended to supersede information contained in customer regulations,
technical manuals/documents, positional handbooks, or other official
publications. The copy of this manual provided to the customer will not be
updated to reflect current data.
Customers using this manual should report errors or omissions,
recommendations for improvements, or other comments to MF Enterprises,
300 Industrial Park Road, Starkville, MS 39759. Phone: (662) 323-5869;
FAX: (662) 323-6551. Business hours: M-F 8-4:30 CST.
MFJ-266C HF/VHF/UHF Antenna Analyzer Instruction Manual
Version 2A iii 2012 MFJ Enterprises, Inc
Contents
1.0 Introduction........................................................................................................... 1
2.0 Power Sources........................................................................................................ 2
2.1 Internal Batteries............................................................................................... 2
2.2 External Power Supply...................................................................................... 3
3.0 Operating Mode ..................................................................................................... 3
3.1 Display Bac light.............................................................................................. 3
3.2 Main Menu Screen............................................................................................ 4
3.3 Frequency Counter Mode (D -> FC) ................................................................. 4
3.4 Antenna Analyzer Mode (U -> ANT) ............................................................... 5
3.5 RF Signal Source .............................................................................................. 5
3.6 L/C Measurement Mode ................................................................................... 5
4.0 Frequency Selection .............................................................................................. 6
4.1 Variable Tuning ................................................................................................ 6
4.2 Range Selection ................................................................................................ 6
4.3 HF-Band Selection............................................................................................ 6
5.0 Accuracy Limits..................................................................................................... 7
5.1 SWR Measurements and Local Interference ..................................................... 7
5.2 Chec ing for Local Interference........................................................................ 7
5.3 Detector Linearity and Accuracy....................................................................... 7
5.4 Calibration-Plane Error..................................................................................... 8
5.5 Sign Ambiguity (± j) ......................................................................................... 8
6.0 Antenna Measurements .......................................................................................... 9
6.1 Antenna Connectors.......................................................................................... 9
6.2 SWR.................................................................................................................. 9
6.3 Measuring SWR................................................................................................ 9
6.4 SWR, Bandwidth, and Resonance................................................................... 10
6.5 Antenna Tuning .............................................................................................. 10
6.6 Antenna matching ........................................................................................... 11
6.7 Matching Antennas Through A Tuner (ATU)................................................. 11
6.8 Antenna Impedance Readings ......................................................................... 11
6.9 Unpredictable SWR ........................................................................................ 12
7.0 Advanced Functions............................................................................................. 12
7.1 Frequency Measurement ................................................................................. 12
7.2 Field Strength Measurement ........................................................................... 12
7.3 Stimulus Generator as a Signal Source............................................................ 13
7.4 Measuring Un nown Capacitance................................................................... 13
7.5 Measuring Un nown Inductance..................................................................... 14
7.6 Tuning a ¼-Wave or ½-Wave Coaxial Stub.................................................... 14
7.7 Determining Velocity Factor........................................................................... 15
7.8 Testing RF Transformers ................................................................................ 15
7.9 Chec ing HF Baluns ....................................................................................... 16
7.10 Chec ing Coax Cable.................................................................................... 16
8.0 Quic Guide to Analyzer Controls and Functions ................................................ 17
Technical Assistance.................................................................................................. 19
12 MONTH LIMITED WARRANTY ....................................................................... 20
MFJ-266C HF/VHF/UHF Antenna Analyzer Instruction Manual
Version 2A 1 2012 MFJ Enterprises, Inc
1.0 INTRODUCTION
Important: Read Section-2 before attempting to use your analyzer --
applying incorrect operating voltages could result in permanent damage!
Also, never apply a DC voltage to the antenna connector
General Description: The MFJ-266C is a self-contained handheld RF
analyzer that performs the following diagnostic functions:
SWR (1:1 to 9.9:1)
Complex Impedance (Z = R + jX)
Impedance Magnit de (Z = Ω)
Capacitance (pF)
Ind ctance ( H)
Relative Field Strength (mV)
Freq ency (MHz)
The MFJ-266C also generates a 2-dBm RF signal that may be used to check
receivers, networks, amplifiers, and antenna patterns Operating range is:
HF: 1.5 - 68 MHz in six HF bands
VHF: 108-230 MHz contin o s coverage
UHF: 305-490 MHz contin o s coverage
A 10:1 vernier drive provides smooth tuning Measurements are displayed
on an easy-to-read LCD screen with optional backlighting Power is supplied
by internal AA cells, an 18650 Li-ion cell or by a regulated 12-VDC external
power source (not included) Weighing just over 1 3 pounds, the MFJ-266C
package fits comfortably in one hand for convenient bench work or on-the-
fly testing in the field Operation is simple, but you will need to read the
manual to learn all of the unit's features and functions The more you know
the more valuable it will become as a diagnostic tool
MFJ-266C HF/VHF/UHF Antenna Analyzer Instruction Manual
Version 2A 2 2012 MFJ Enterprises, Inc
2.0 POWER SOURCES
The MFJ-266C may be powered with internal AA batteries, 18650 Li-ion
cell or with an external DC supply To avoid needless damage and ensure top
performance, please follow the guidelines below when choosing a voltage
source
2.1 Internal Batteries
To access the jumpers and battery compartments, remove all four screws
securing the analyzer's back cover and carefully open the case To operate
the MFJ-266C on batteries put the EXT PWR-BAT jumper on the PC board
in the BAT position and install the batteries
The MFJ-266C can use either AA cells or a 18650 LI-ion cell to power it on
batteries
AA Battery power requires 4 (four) AA-size 1.5-volt alkaline cells Batteries
are installed in a fully encased 4-cell plastic tray mounted inside the analyzer
enclosure Slide the battery box covers sideways to unlatch, and then lift
vertically to expose the cells
Slide and
Lift
When replacing old batteries, be sure to follow the manufacturer's
environmental guidelines for safe disposal For longest battery life, always
replace with a matched set of factory-fresh cells The MFJ-266C will not
charge batteries in the AA cell pack Do not use rechargeable AA cells in the
pack
The MFJ-266C can also hold an optional rechargeable 18650 battery This
battery is inserted into a holder that is at the bottom of the case Disassemble
the case as listed above and insert the battery into the holder making sure the
polarity is correct This battery is recharged from the external supply through
a special charging circuit built into the MFJ-266C Charging time is about 10
hours using the MFJ-1312B The 18650 battery will only charge when the
MFJ-266C is off For
charging the position of the
EXT PWR-BAT jumper
does not matter It will
charge in either position
To switch between the AA
cell pack and the
rechargeable 18650 unplug
the 3 pin header from the
AA cell pack and plug in
the 3 pin header from the
MFJ-266C HF/VHF/UHF Antenna Analyzer Instruction Manual
Version 2A 3 2012 MFJ Enterprises, Inc
18650 pack
2.2 External Power Supply
To operate the MFJ-266C on an external power supply open up the unit and
move the EXT PWR-BAT jumper from to EXT PWR The MFJ-266C will
not run on external power and batteries at the same time
Powering the MFJ-266C externally requires a well-filtered 12V DC supply
such as the MFJ-1312D capable of delivering 12 to 15 VDC under varying
load conditions Current drain ranges from 30 mA to 180 mA, depending on
operating mode, frequency range, and whether or not the display backlight is
on The unit's external power jack is located on the front panel and accepts a
standard 2 1-mm power plug Positive voltage (+) must be applied to the
connector's center pin.
+
-
+
-
2.1 mm
mportant Warnings: Reverse polarity or excessive voltage could
permanently damage the MFJ-266C! To avoid damage:
1. Never connect an AC transformer or positive-ground power source
2. Never install or remove batteries with external power connected
3.0 OPERATING MODE
Once you have suitable power (battery or external), you're ready to explore
the analyzer's basic operating features Begin by pressing the red P R
button on
BAND-MODE
SELECT
Up Down
ANT Counter
Bk Lite
PWR
ON
OFF
3.1 Display Backlight
When the analyzer comes on, the screen displays a brief 1-second prompt
before automatically switching to the main menu This prompt allows you to
turn on the optional display backlight If you elect to use it, press the Up
button immediately, before the screen changes to the main menu and hold it
down until the backlight comes on If you ignore the prompt, the backlight
will remain off Off is the default setting to reduce battery drain
MFJ-266C HF/VHF/UHF Antenna Analyzer Instruction Manual
Version 2A 4 2012 MFJ Enterprises, Inc
3.2 Main Menu Screen
The main menu screen has two purposes:
(1 ) Power Supply Voltage: Appears on the right side of the screen If it
falls outside the 3 5 to 5V operating window of the battery packs, be sure to
change batteries or make power supply adjustments
(2 ) Operating Mode Prompt: On the left side of the screen This prompts
you to select between the two primary operating modes (see below)
D >FC DC:12.00V
U >ANT Analyzer
Supply Voltage"Down" for Counter
"Up" for Antenna Analyzer
(3 ) (D >FC) Press the “Down” button to select Frequency Counter mode
(4 ) (U > ANT Analyzer) Press the “Up” button to select the Antenna
Analyzer mode
3.3 Frequency Counter Mode (D -> FC)
In this setup, the MFJ-266C functions as a 1-500 MHz frequency counter
Note that the BAND SELECT switch B must be "up" in the HF position for
the counter mode to activate. If switch B is down, an error message will
prompt you to change the band setting to HF
AB
BAND SELECT
BAND A B
HF X
VHF
UHF
Counter X
UP
When a signal is applied to the Antenna jack, the frequency is displayed in
MHz Two gate speeds are available The default gate speed is Fast (or Fg --
see the top right-hand side of the display) The fast gate provides 1-kHz
resolution The alternative gate speed is Slow (or Sg), which provides 100-
Hz resolution To change the gate speed:
(1 ) For Fast Gate, press the UP button
(2 ) For Slow Gate: press the DO N button
Fg f: 010.000 MHz
REF FS: 100mV
Gate Speed Frequency Readout
Relative Field Strength
The Counter mode also provides relative Field Strength (REF FS) This
feature is useful for conducting relative field-strength tests, estimating input
levels to the counter, and detecting local signals that could impact SWR
accuracy (see Section 7 2)
MFJ-266C HF/VHF/UHF Antenna Analyzer Instruction Manual
Version 2A 5 2012 MFJ Enterprises, Inc
3.4 Antenna Analyzer Mode (U -> ANT)
In this mode, the analyzer's built-in stimulus generator drives a bridge circuit
and the unit functions as a network analyzer The top line of the screen
displays band selection (a single letter) and the operating frequency in MHz
(see Section-4) The bottom line simultaneously displays complex
impedance (Z = R+JX), impedance magnitude (Z = Ω), and S R for any
load connected to the antenna jack Note that only SWR is displayed in the
UHF operating range
50+j 0 50 1.0
Stimulus Frequency
Band (Frequency) Selection
SWR (1.0:1)
10.000MHz D SWR
Impedance Magnitudeomplex Impedance
3.5 RF Signal Source
RF output from the MFJ-266C’s built-in stimulus generator is available at
the ANT connector in Analyzer mode This signal is a +2 dBm continuous
carrier When using the analyzer as a signal source, the operating range,
band, and frequency are selected in the normal manner and will be displayed
on the screen (see Frequency Selection, Section-4)
3.6 L/C Measurement Mode
The MFJ-266C may be used to measure the value of unknown capacitors and
inductors To measure L/C values, connect the device to be tested to the
antenna jack and follow the procedure outlined below:
Measure Capacitance
Turn the analyzer off, then press and hold the Up button while turning
PWR back on. The screen will display the value in pF along with the
stimulus frequency being used for the measurement
Measure Inductance
Turn the analyzer off, then press and hold the Down button while turning
PWR back on The display will show inductance in uH along with the
stimulus frequency
5.000MHz D C=
122 pF
Capacitance
Frequency Band
5.000MHz D L=
10.200 uH
Inductance
Frequency Band
5.000MHz D C=
Xc>1.5k
Frequency Band
Reactance out of Range
Change Stimulus Frequency
MFJ-266C HF/VHF/UHF Antenna Analyzer Instruction Manual
Version 2A 6 2012 MFJ Enterprises, Inc
4.0 FREQUENCY SELECTION
The MFJ-266C covers the HF region (1.5-71 MHz) in six bands, plus VHF
(85-185 MHz) and UHF (300-490 MHz) Tuning and band-selection are
electronically switched for high reliability
4.1 Variable Tuning
The TUNE control uses an instrumentation-grade potentiometer with a 10:1
drive reduction to ensure gradual tuning on each band Note that a
mechanical lock is provided on the side of the TUNE knob assembly The
lock is used to prevent accidental changes once a desired frequency is set
Dial Lock
TUNE
4.2 Range Selection
BAND SELECT buttons A and B are used to toggle between the HF, VHF,
and UHF ranges Follow the up/down position prompts shown in the table
printed next to the buttons to select ranges
AB
BAND SELECT
BAND A B
HF X
VHF
UHF
Counter X
X means the VHF/UHF switch can be in either position Tuning is
continuous in the VHF and UHF ranges The frequency readout line of the
display shows both the operating frequency in MHz and the letter of the
selected range
Band V: 108 to 230 MHz (Airband, 2 Meters, VHF 2-Way and 1 2 Meters)
Band U: 308 to 490 MHz (Military, 70-cm, UHF 2-way)
4.3 HF-Band Selection
The UP and DO N buttons are used to step or scroll through a selection of
six HF bands To step up or down in one-band increments, quickly tap the
appropriate switch to initiate each change To scroll, press and hold the
switch down Most users find it easier to watch the letter designation for the
desired band rather than watch the frequency display when making a
selection:
MFJ-266C HF/VHF/UHF Antenna Analyzer Instruction Manual
Version 2A 7 2012 MFJ Enterprises, Inc
A: 1 5 to 2 7 MHz (160 Meters)
B: 2 5 to 4 8 MHz (80/75 Meters)
C: 4 6 to 9 6 MHz (60,40 Meters)
D: 8 5 to 18 7 MHz (30,20,17 Meters)
E: 17 3 to 39 MHz (17,15,12,10 Meters)
F: 38 7 to 71 MHz (6 Meters)
Before moving on to the next section, take time to review the MFJ-266C’s
basic set-up procedures Operation becomes second nature quickly, but
should you need it, there’s a supplemental "quick guide" in the back for
reference (Section 8 0) The remainder of the manual will focus on general
instructions and helpful tips for making accurate measurements
5.0 ACCURACY LIMITS
The MFJ-266C will serve as your “eyes and ears” when working with RF
systems, and it can deliver results that rival units costing thousands of
dollars However, all handheld analyzers share certain limitations, and being
aware of them will help you to achieve more meaningful results
5.1 S R Measurements and Local Interference
The MFJ-266C (and other hand-helds) use a broadband diode detector that is
open to receiving signals across the entire radio spectrum Most of the time,
the unit's built-in stimulus generator is powerful enough to overcome any
lack of front-end selectivity and override stray pickup However, a powerful
transmitter located nearby could inject enough RF energy into the detector to
disrupt readings If this condition occurs, performance will become erratic
and SWR readings may appear higher than they really are
5.2 Checking for Local Interference
Unlike many analyzers, the MFJ-266C has an onboard function for
identifying local interference Simply switch to the analyzer's Frequency
Counter (FC) mode and note the readings you obtain with the antenna
connected If a strong signal (>100 mV) registers on the field-strength
display (FS) and the counter shows the frequency of a known local broadcast
station or radio service (f:), then suspect interference If the interfering
source can't be turned off or your antenna can't be moved to a different
location, you may need to use a station transceiver and a thru-line directional
Wattmeter to complete the adjustments
5.3 Detector Linearity and Accuracy
Diode detectors typically become non-linear at very low voltages Because
of diode non-linearity, it's not uncommon for two identical analyzers to show
slightly different readings when checking a load with very low SWR (or low
RF-return voltage) For example, one analyzer may read 1 2:1 while another
reads 1 1:1 when checking the same antenna The MFJ-266C is
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