MFJ MFJ-213 User manual

ME)
MEFJ Antenna Analyzer
1.0 to 60.0 MHz
Model MFJ-213
INSTRUCTION MANUAL
CAUTION: Read All Instructions Before Operating Equipment
MFJ ENTERPRISES, INC.
300 Industrial Park Road
Starkville, MS 39759 USA
)2-323-5869 Fax: 662-323. Tel: 66: 6551
CopymianT 2013 MS ENTERPRIBES, INC.

MFJ-213 HF/VHF/UHF Antenna Analyzer Instruction Manual
DISCLAIMER
Information in this manual is designed for user purposes only and is nof|
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 MFJ Enterprises,
300 Industrial Park Road, Starkville, MS 39759. Phone: [phone];
FAX: [phone]. Business hours: M-F 8-4:30 CST.
Version 1 ii © 2012 MFI Enterprises, Inc

MFJ-213 HF/VHF/UHF Antenna Analyzer Instruction Manual
Contents
1.0 Introduction me
2.0 Power Sources ..
2.1 Internal Batteries.
2.2 External Power Supply..
3.0 Operating Mode...
3.1 Main Menu Screen...
3.1.1 Antenna Analyzer Mode (1.Antenna)
3.1.2 Return Loss (2.Loss)
3.1.3 L/C Measurement Mode (3.LC-meter)
3.1.4 Li-ion Battery Charge (4.Chr)
3.1.5 Bluetooth link (6.BTIk
4.0 Frequency Selection.
4.1 Variable Tuning.
4.2 HF-Band Selection
5.0 Accuracy Limit
5.1 SWR Measurements and Local Interference
5.2 Checking for Local Interference.
5.3 Detector Linearity and Accuracy
5.4 Calibration-Plane Error
5.5 Sign Ambiguity (+ j)
6.0 Antenna Measurement:
6.1 Antenna Connector:
6.2 SWR
6.3 Measuring SWR
6.4 SWR, Bandwidth, and Resonanci
6.5 Antenna Tuning.
6.6 Antenna matching
6.7 Matching antennas through a tuner (.
6.8 Antenna Impedance Readings .
6.9 Unpredictable SWR.
7.0 Advanced Functions.
7.1 Stimulus Generator as a Signal Sourc
7.2 Measuring Unknown Capacitance.
7.3 Measuring Unknown Inductance.
7.4 Determining Cable Velocity Factor
7.5 Tuning a %4-Wave or '4-Wave Coaxial Stub..
7.6 Checking Coax Cable.
7.7 Testing RF Transformers ..
7.8 Checking HF Baluns ..
NOTES:
8.0 Quick Guide to Analyzer Controls and Functions .
Powe
Power Up:
Main Menu Screen:
Set Up Stimulus Frequency:
Return Loss Function (2.Loss):
LIC Function (3,LC-mets
Charging Function (4.Chr
Technical Assistance ..
12 MONTH LIMITED WARRANT"
2
Version 1 iii © 2012 MFI Enterprises, Inc

—
MFJ-213
HF/VHF/UHF
Antenna
Analyzer
Instruction
Manual
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-213 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 Magnitude (Z in Q)
Return Loss (in dB)
Cable Loss (in dB)
Capacitance (in pF)
Inductance (in uH)
The MFJ-213 also generates a 0-dBm RF signal that may be used to check
receivers, networks, amplifiers, and antenna patterns. Operating range is:
HF: 1.00 — 60.00 MHz
The
MFJ-213
uses
a
DDS
signal
generator
giving
a
stable
0dBm
signal
tuned
by a rotary
encoder.
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-213
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.
Version 1 1 © 2012 MFI Enterprises, Inc

MFJ-213 HF/VHF/UHF Antenna Analyzer Instruction Manual
2.0 POWER SOURCES
The MFJ-213 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-213 on batteries put the EXT PWR-BAT jumper on the PC board in
the BAT position and install the batteries.
The MFJ-213 can use either AA cells or a 18650 LI-ion cell to power it on
batteries.
AA Battery power requires 3 (three) AA-size 1.5-volt alkaline cells.
Batteries are installed in a fully encased 3-cell plastic tray mounted inside
the analyzer enclosure. Slide the battery box covers sideways to unlatch, and
then lift vertically to expose the cells.
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-213 will not
charge batteries in the AA cell pack. Do not use rechargeable AA cells in the
pack. The battery pack plugs into the socket on the bottom of the PC Board.
The MFJ-213 can also hold an optional
rechargeable 18650 battery and charger
board. This battery is inserted into a
holder that is placed 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 (optional) that plugs into
the MFJ-213. Charging time is about 10
hours using the MFJ-1312B. See the section on the charging function below
for charging the battery. The battery holder has a circuit built in to prevent
the battery from discharging below the minimum safe voltage. If the battery
has discharged to that point or a new battery has been put in the battery must
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MFJ-213 HF/VHF/UHF Antenna Analyzer Instruction Manual
be charged above that point resetting the circuit before a Li-ion battery will
function in the MFJ-213.
2.2 External Power Supply
To operate the MFJ-213 on an external power supply plug in an external
power supply onto the EXT PWR jack on the top of the unit..
Powering the MFJ-213 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.
Important Warnings: Reverse polarity or excessive voltage could
permanently damage the MFJ-213! 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 PWR
button on.
BAND ESC MODE
PWR
ON
morF
3.1 Main Menu Screen
The individual functions are listed on the main screen and are selected by
rotating the TUNE/SELECT knob then pushing the TUNE/SELECT knob to
select the function. To exit from any of the functions press the ESC button to
return to the Main Menu Screen.
»BT1k
1 ard Fr
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MFJ-213 HF/VHF/UHF Antenna Analyzer Instruction Manual
3.1.1 Antenna Analyzer Mode (1.Antenna)
The MFJ-213 may be used to measure the impedance, complex impedance
and SWR of an antenna connected to the antenna connector in this function.
There are 3 sub-modes selected with the MODE button. Default is the
impedance measurements. The next mode reads the external power supply
voltage (Pv) when connected to an external charger and the battery voltage
(Bv) when batteries are installed. When the external supply or internal
batteries are not installed then those numbers are not valid. The third mode is
a measurement of external noise that can cause erroneous readings.
Stimulus Frequency
=A
\plex Taianee 3.1.2 Return Loss (2.Loss)
Impedance Com
This function on the MFJ-213 reads the return loss and SWR of an antenna
connected to the antenna connector. There are two modes in this function.
The default is return loss and the next mode selected by pressing the MODE
button is cable loss. The cable loss is measured by connecting the cable to
the antenna connector and leaving the other end open or unterminated. This
mode is for 50 ohm cables.
Stimulus Frequency Stimulus Frequency
Return Loss SWR 3.1.3 LIC Return Loss SWR
Measurement Mode (3.LC-meter)
The MFJ-213 may be used to measure the value of unknown capacitors and
inductors. To measure L/C values, select this function, connect the device to
be tested to the antenna jack and follow the procedure outlined below:
Measure Capacitance
If the display does not indicate Xc in the top line and C= in the second line
press the MODE button till this mode is selected. The capacitance at that
frequency is displayed and the capacitive reactance is displayed to the far
right.
Stimulus Frequency
Mb
C FF 13
Capacitance
Reactance
Measure Inductance
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MFJ-213 HF/VHF/UHF Antenna Analyzer Instruction Manual
Press the MODE button till the display indicates XL in the top line and L=
in the second line this mode is selected. The inductance at that frequency is
displayed and the inductive reactance is displayed to the far right.
Stimulus Frequency
18, oi MHz
L= WH
Inductance SWR
3.1.4 Li-ion Battery Charge (4.Chr)
Charging the Li-ion battery is done using a special charger (optional)
plugged into the MFJ-213. The external power supply must first be plugged
into the unit for the charger to function. Note just plugging the external
supply will not charge the battery. To charge the Li-ion battery if installed
you rotate the TUNE/SELECT knob to this function then press the
TUNE/SELECT knob in. The charging circuit will come on displaying
CHARGING and will run till fully charged.
3.1.5 Bluetooth link (6.BTIk)
This is an option that is plugged into the MFJ-213 allowing you to
link the MFJ-213 to an android device. See the installation
instructions with this option on installation and use.
4.0 FREQUENCY SELECTION
The MFJ-213 covers the HF region (1.5-60 MHz)
4.1 Variable Tuning
The MFJ-213 tunes continuously from 1.500 to 60.000 MHz by turning the
TUNE/SELECT knob. The tuning speed can be selected by pushing in the
TUNE/SELECT knob to select which digit to increment. The frequency
displayed on the LCD display will have a bar under the digit that will be
incremented and pushing in the knob advances the bar to the next digit
between 1 KHz and | MHz in the Analyzer mode and 10Hz and 1 MHz in
the other modes.
Stimulus Frequency
a
You can select each of the amateur bands instead of turning the tuning knob
by pressing the BAND button.
- 88
Frequency Step Marker
4.2 HF-Band Selection
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MF/J-213 HF/VHF/UHF Antenna Analyzer Instruction Manual
Before moving on to the next section, take time to review the MFJ-213’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-213 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 SWR Measurements and Local Interference
The MFJ-213 (and other hand-helds) uses 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-213 has an onboard function for identifying
local interference. In the 1.Antenna function simply switch to the third mode
and note the readings you obtain with the antenna connected. If a strong
signal (>100) registers on the display, 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.
Stimulus Frequency
Noise
level
Noise
indicator
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-213 is electronically
compensated to minimize detector error, but be aware of the potential for
minor differences.
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MFJ-213 HF/VHF/UHF Antenna Analyzer Instruction Manual
5.4 Calibration-Plane Error
The analyzer’s calibration plane is the point of reference where all
measurements have the greatest accuracy (gain reference=0 dB, phase shift
= 0-degrees). For basic hand-held units like the MFJ-213, the calibration
plane is fixed at the antenna connector. As such, any measurement made
through a cable will displace the load from the calibration plane and
introduce some amount of error. For SWR readings, error is mainly caused
by losses in the cable. Specifically, SWR will read somewhat lower through
a length of cable than with the analyzer connected directly to the direct load
because the forward and reflected stimulus signals are attenuated in the
feedline. The more loss there is in the cable, the greater the error. Most of the
time, this inaccuracy isn’t a problem because the SWR you measure with the
analyzer is the same SWR the radio will encounter when connected.
However, if you wish to know the antenna’s actual feedpoint SWR for
documentation purposes, the analyzer should be connected directly to the
feed point through a short pigtail.
Calibration-plane error has a much more significant impact when attempting
to measure impedance values because of phase rotation in the cable. In fact,
impedance readings can swing dramatically, depending on the cable’s
electrical length and the severity of the load’s mismatch with reference to 50
Ohms. For accurate impedance data, always connect the analyzer directly to
the antenna or device you're testing using the shortest lead possible.
5.5 Sign Ambiguity (+ j)
Most hand-held analyzers (including the MFJ-213) lack the processing
capability to calculate the reactance sign for complex impedance (Z = R + j).
By default, the MFJ-213 displays a plus sign (+ j) between the resistive and
reactive values, but this sign is merely a placeholder and not a calculated
data point. Although the analyzer’s processor can’t calculate sign, it can
often be determined with a small adjustment of the TUNE control. To
determine sign, TUNE the analyzer up-frequency slightly --
(1.) If reactance decreases, the sign is likely to be ( - ) and the reactance
capacitive (Xc).
(2.) If reactance increases, the sign is likely to be ( + ) and the reactance
inductive (X:).
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MFJ-213 HF/VHF/UHF Antenna Analyzer Instruction Manual
6.0 ANTENNA MEASUREMENTS
Excellent tutorials are available in ARRL Handbooks and other League
antenna publications to help you master the art and science of constructing
and adjusting effective antenna systems. Informative introductory material
may also be found on line, but choose carefully. Not all web material is well
edited or accurate (especially items discussed in chat rooms and forums).
Here are some general guidelines to help you get started.
6.1 Antenna Connectors
The MFJ-213 uses a SO-239-female (or UHF) connector. Stacking multiple
adapters together places unnecessary stress the analyzer’s connector and
increases the possibility of measurement error.
6.2SWR
Standing Wave Ratio (SWR), sometimes referred to as VSWR, is the most
widely used format for checking tuning error and impedance mismatch
between antennas and radios. The MFJ-213 is calibrated to work on the 50-
ohm impedance standard used by amateur and commercial two-way
equipment (Zo=50). Unless a different cable impedance is specified by the
antenna designer for matching purposes, always use 50-Ohm cable of known
quality when making up transmission lines and patch cables.
WARNING: Never apply external dc voltages or strong RF signals to the
analyzer’s antenna connector or permanent damage will result. Also,
never connect the output of a transmitter to your analyzer.
6.3 Measuring SWR
Here is the recommended procedure for the checking antenna SWR with the
MFJ-213:
(1.) Turn the unit ON and select the Antenna function (Section-3).
(2.) Select the desired Frequency (Section-4).
(3.) Connect the antenna to the analyzer (Antenna connector)*.
(4.) Rotate the Tune knob to find the lowest SWR reading and write it
down.
(5.) Rotate Tune to either side of minimum SWR and note the 2:1 SWR
points.
*When testing large ungrounded antenna systems such as HF dipoles,
momentarily short the feedline center pin to ground to bleed off static
buildup before connecting to the analyzer.
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MFJ-213 HF/VHF/UHF Antenna Analyzer Instruction Manual
6.4 SWR, Bandwidth, and Resonance
The amateur-radio industry's standard for maximum SWR is 2:1. Most
modern transceivers operate safely and deliver full power within this
mismatch range. The antenna bandwidth is the frequency interval between
its two 2:1 SWR points. This specification, along with minimum SWR and
minimum SWR frequency, is often included on antenna specification sheets.
Note that minimum SWR is sometimes wrongly confused with resonant
Srequency. The technical definition for resonance is the frequency where
inductive and capacitive reactance cancels, leaving a purely resistive load
(4 = 0). The minimum SWR and resonant frequencies may be close, but
they rarely coincide.
6.5 Antenna Tuning
Where possible, make adjustments to your antenna that will yield SWR
readings under 2:1 over the frequency range where you normally operate. If
the minimum-SWR frequency measures low in the band (or below the band
edge), your antenna is probably too long and will need to be shortened. If the
Minimum SWR frequency is too high, it should be lengthened. To calculate
the required change in length:
(1.) Write down the desired minimum SWR frequency (ex: 14.200 MHz)
(2.) Use the analyzer to measure the present minimum SWR frequency (ex:
14.050 MHz)
(3.) Divide the present frequency by the desired frequency (ex 14.050 +
14.200 = .989)
(4.) Multiply the present length by the result (33.3 feet x .989 = 32.94 feet)
Note that this formula applies to full-sized antennas, but not to elements
shortened by coils, traps, or capacitive hats.
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MFJ-213 HF/VHF/UHF Antenna Analyzer Instruction Manual
6.6 Antenna matching
If your antenna doesn’t exhibit 1:1 SWR at the minimum SWR frequency,
then some mismatch is present relative to 50-Ohms. For simple dipoles and
ground-independent verticals, mounting height above ground may be the
primary cause. Generally, it’s best to ignore SWR readings under 2:1 and
mount these antennas as high as possible where they’ll perform best. For
antennas that feature adjustable matching networks (Yagis etc), SWR can
usually be improved by following the manufacturer’s antenna setup
instructions. Note that matching and tuning settings may interact, so
readjustment of both the antenna’s element length and matching network
may be needed to obtain best results.
6.7 Matching antennas through a tuner (ATU)
If your antenna can’t be tuned or matched to an acceptable SWR level by
making physical adjustments, then an external antenna tuner (ATU) should
be installed. The MFJ-213 may be used in conjunction with the tuner to
make adjustments without the need to transmit test signals over air. Simply
connect the analyzer to the tuner input (radio side) through a short patch
cable. Select the Analyzer mode, set up the Band, and Tune for the desired
frequency of operation. Then, adjust the antenna-tuner's controls following
the manufacturer's recommendations until SWR approaches 1:1. Remove the
analyzer, reconnect the radio, and the load will be pre-matched to the radio's
50-Ohm operating impedance.
6.8 Antenna Impedance Readings
The MFJ-213 displays complex impedance and impedance magnitude
readings on the same screen with the SWR reading. However, when
measuring through coax, remember that the impedance readings are phase-
shifted values appearing at your end of the cable and not the actual feedpoint
impedance of the antenna itself (Section-5.4). As a “work-around” strategy,
it’s possible to measure the antenna’s actual impedance remotely if the
feedline is cut to an exact electrical half wavelength. In a half-wavelength
line, the phase shift is a full 360 degrees, which electrically rotates the
analyzer’s calibration plane back into alignment with the load. However, this
strategy only works at one frequency and errors compound quickly if your
cable is multiple half-wavelengths long. As a practical matter, unless you
have an advanced working knowledge of transmission-lines, Smith charts,
and impedance matching theory, it’s best to ignore impedances and rely on
SWR for routine antenna-system adjustments.
6.9 Unpredictable SWR
A change in feedline length shouldn't shift your antenna's minimum-SWR
frequency or have much impact on the SWR readings. If it does, suspect a
significant mismatch between the antenna and coax, or more likely, poor
Version 1 10 © 2012 MFI Enterprises, Inc

$i
MFJ-213
HF/VHF/UHF
Antenna
Analyzer
Instruction
Manual
isolation
between
the
feedline
and
the
antenna.
Isolation
problems
typically
occur
when
unbalanced
coax
line
is
connected
directly
to
a
balanced
element
such
as
a
dipole
or
a
loop,
and
the
outer
surface
of
the
coax
shield
literally
becomes
a part of the antenna.
If the length
of the shield
happens
to
presents
a
low
impedance
path,
it
can
load
the
element
significantly
and
shift
the
minimum-SWR
frequency
unpredictably.
It
will
also
introduce
needless
mismatch,
divert
transmitted
RF back
toward
the operating
position,
causing
RFI
problems
in
the
residence,
and
increase
unwanted
noise
pickup
in
receive
mode.
The
best
way
to
decouple
the
outer
surface
of
the
shield
from
the antenna
element
is with
a balun.
Current-type
baluns
work
best because
they
have
higher
power-handling
capability
and less loss than
other
types.
An
effective
current
balun could
be
as
simple
as
a
few
loops
of
coax
taped
together
at the feedpoint,
but for best
common-mode
rejection,
a Guanella-
style
balun
wound
on a ferrite
core
is recommended.
7.0 ADVANCED FUNCTIONS
Here are some of the MFJ-213 advance functions. Note that some of these
procedures involve connecting component leads to the unit's Antenna
connector. For these connections, we suggest making up a very short UHF-
male coaxial pigtail or obtaining a UHF dual binding post adapter to prevent
damage the center-contact of the analyzer connector.
7.1 Stimulus Generator as a Signal Source
When operated in Analyzer mode, the MFJ-213 generates a 0 dBm CW
carrier (1 mW). See section 3.1.1 for setup procedures. Output will vary
slightly, depending on frequency and operating voltage, but typically holds
to within 1-2 dB of the rated power level over the analyzer's frequency
range. Harmonic suppression averages -20 dBc. A quarter-wave stub or low-
pass filter may be installed if greater harmonic suppression is required for a
specific application. Frequency stability and carrier purity are sufficient for
testing filters, mixers, low-power amplifier stages, and for checking antenna
patterns when a range antenna is connected to the analyzer output. The
stimulus generator may also be used for producing lower-level signals with a
suitable precision RF attenuator installed in line. When connecting the
generator directly to active circuitry, always insert a coupling capacitor to
prevent DC voltages from back-feeding into the bridge circuit and destroying
the detector diodes. Also, avoid connecting the stimulus signal directly to
sensitive preamps or receiver circuits that could be damaged by an un-
attenuated 1-mW signal.
Version 1 i © 2012 MFJ Enterprises, Inc

MFJ-213 HF/VHF/UHF Antenna Analyzer Instruction Manual
7.2 Measuring Unknown Capacitance
To measure capacitance, connect the unknown component to the Antenna
connector (usable range is from approximately 15 pF to 1200 pF). To enter
the Capacitance mode, begin with the analyzer at the main menu and select
the LC-meter function (see Section 3.1.3). The screen will display the
approximate value of the unknown capacitor in pF along with the stimulus
frequency where the measurement is being made. The best accuracy is
typically obtained in the 4 to 9 MHz range, which may be selected using the
BAND button and the TUNE knob. Note that any capacitor and lead
combination that approaches self-resonance at the stimulus frequency will
trigger the C = Xc >1.5KQ message and will be un-measurable. Attempt to
re-measure at a lower frequency.
7.3 Measuring Unknown Inductance
To measure inductance, connect the unknown component to the Antenna
connector. To enter the Inductance mode, begin with the analyzer at the
main menu and select the LC-meter function then press the MODE button
to select the inductance mode(see Section 3.1.3).The screen will display the
approximate value of the unknown inductor in uH along with the stimulus
frequency where the measurement is being made. The best accuracy is
typically obtained in the 2 to 9 MHz range, which may be selected using the
BAND button and the TUNE knob. Note that any inductor approaching self-
resonance at the stimulus frequency will trigger the L = X, >1.5KQ message
and will be un-measurable. Try to re-measure at a lower frequency.
7.4 Determining Cable Velocity Factor
If you have coax cable with an unknown velocity factor, you can determine
it quickly using the following procedure:
(1.) Set the MFJ-213 up in Analyzer mode (Section-3)
(2.) Set the frequency to around 20 MHz (Section-4)
(3.) Make a 1/4-A stub from 9 feet of the unknown cable and connect it to the
analyzer (other end open)
(4.) Rotate Tune for minimum impedance magnitude reading. Write down
the frequency (in MHz)
(5.) Divide 246 by this frequency to find the free-space 1/4-A wavelength in
feet (L = 246 +f MHz)
(6.) Divide 9 (the actual length) by free-space 1/4- wavelength to get the
Velocity Factor (VF =9 +L)
Note that there is nothing magical about the 9-foot stub length, other than it
falls conveniently within the limits the tuning range. Other lengths could be
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MFJ-213 HF/VHF/UHF Antenna Analyzer Instruction Manual
used. Shorter stubs will yield poorer accuracy and long ones may needlessly
waste useful cable.
7.5 Tuning a '4-Wave or '2-Wave Coaxial Stub
To accurately tune a coaxial stub, begin by calculating the free-space length
at the stub's intended operating frequency:
For 1/4-A in inches = 295] + MHz
For 1/4-A in feet = 246 + MHz
For 1/2-A in inches = 5902 + MHz
For 1/2-A In feet = 492 + MHz
Next, multiply the free-space length times your cable's velocity factor.
Finally, add at least 10% to this length for a margin of error (better too long
than too short). Cut the cable to this initial length. Connect one end of the
cable to the analyzer's Antenna connector. For a 1/4-A stub, leave the far
end open. For a 1/2-A stub, short the far end. Next:
(1.) Set the MFJ-213 to Antenna mode (Section-3)
(2.) Initially, set the Band and Tune for the desired stub frequency (Section-
4)
(3.) *Tune down in frequency to find lowest impedance-magnitude reading
(a 1/4-A open or a 1/2-A short look like a short or low impedance load).
(4.) Write your measured frequency down.
(5.) Divide the measured frequency by the desired stub frequency to obtain a
correction factor
(6.) Multiply the present stub length by the correction factor to get the
desired stub length.
(7.) Re-cut the cable to that length.
*Note that the impedance value may not drop to zero, but it will
begin to increase again as you continue to tune past the null. If the
null reading is broad, choose a frequency at the center.
(4.) Rotate Tune for minimum impedance magnitude reading. Write down
the frequency (MHz)
(5.) Divide 246 by this frequency to find the free-space 1/4-) wavelength in
feet (L = 246 +f MHz)
(6.) Divide 9 (actual length) by free-space 1/4-2 wavelength to get the
Velocity Factor (VF =9 +L)
Note that there is nothing magical about the 9-foot stub length, other than it
falls conveniently within the limits of Band E’s tuning range. Other lengths
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MFJ-213 HF/VHF/UHF Antenna Analyzer Instruction Manual
could be used. Shorter stubs will yield poorer accuracy and long ones may
needlessly waste useful cable.
7.6 Checking Coax Cable Impedance
To check a length of coax cable for impedance error, connect one end to the
analyzer and terminate the far end with a precision (non-inductive) 50-Ohm
resistive load. The cable will need to be at least 1-4 long at 30 MHz for this
test. Set the MFJ-213 up for analyzer mode and tune to 30 MHz. Rotate the
Tune between 15 and 60 MHz while watching the Jmpedance Magnitude
reading. If the cable is 50 Ohms and in good condition, there should be little
change in the impedance magnitude readings. If there are significant
fluctuations, the cable is either not 50 Ohms or is badly contaminated. If
readings cyclically swing between 25 Ohms and 100 Ohms, the cable is 75-
Ohm coax.
7.7 Testing RF Transformers
Broadband HF-matching transformers wound for the 12.5 to 200 Ohm range
may be tested using the MFJ-213. Connect the 50-Ohm (primary) side to the
analyzer connector using a short pigtail or binding post adapter, and attach
the appropriate resistive load across the secondary side (always use a non-
inductive resistor).
Next:
(1.) Set the MFJ-213 up in Analyzer mode (Section-3)
(2.) Set the Band to the desired frequency range (Section-4)
(3.) Rotate Tune across the frequency range and note SWR. Change bands,
as needed.
At the low and high ends of the transformer's frequency response range,
SWR and reactance will climb to unacceptable levels (< 1.2:1 is ideal). HF
tuned transmission-line transformers may be tested in similar fashion by
connecting one end directly to the analyzer and terminating the far end.
However, only precision RF terminations with known impedance
characteristics should be used above 50 MHz. Set up the analyzer for the
desired range and sweep the band of interest using the Tune control.
Transmission-line transformers are “frequency specific” and have much
more limited frequency response.
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MFJ-213 HF/VHF/UHF Antenna Analyzer Instruction Manual
7.8 Checking HF Baluns
A well-designed balun will have low SWR and good balance over its
operating range. The MFJ-213 can test both of these qualities using the setup
shown below. Configure the unit to operate in Analyzer mode in the HF
range. Connect the input (unbalanced) side of the balun to the analyzer’s
antenna connector. Connect a center-tapped resistive load to the balanced
side (R1,R2 = 25Q for 1:1 baluns, R1,R2 = 100Q for 4:1 baluns). Using the
Tune and Band controls:
(1.) Sweep the balun for SWR with the test lead disconnected from the load.
(2.) Connect the test lead to the mid-point (A) and re-sweep. There should be
minimal change.
(3.) Connect it to either side (B) (C). SWR will go up, but should go up
equally on both sides.
Short Test Lead
MF-213
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MFJ-213 HF/VHF/UHF Antenna Analyzer Instruction Manual
NOTES:
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MFJ-213 HF/VHF/UHF Antenna Analyzer Instruction Manual
8.0 QUICK GUIDE TO ANALYZER CONTROLS AND
FUNCTIONS
Power:
Use only 1.5-V Alkaline batteries or 18650 Li-ion battery. External power
must be 10.8-12.5 Vdc, well regulated. Power plug: 2.1-mm, positive (+) to
center pin.
Power Up:
Press PWR, wait for the Main Menu to come up.
Main Menu Screen:
Rotate the Tune knob to select the desired Function then press to select
the function.
S.BT1k
Scroll and Pres
Set Up Stimulus Frequency:
In any function press the TUNE/SELECT knob to set the step size.
Stimulus Frequency
1H.6
a 2
Frequency Step Marker
221.68
Press the BAND button to select the amateur band if desired.
Turn the TUNE knob to set the exact frequency desired.
Analyzer Function Screen (1.Antenna):
Connect the antenna to the Antenna connector.
Set the frequency and read the results.
Stimulus Frequency
Impedance Complex Impedance
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