Deepace KC901M User Manual

Contents

Introduction 1

1 Installation guide 4

1.1 How to choose batteries 4

1.2 How to Install Batteries 4

1.3 How to mount shoulder Strap 6

1.4 How to carry and hold 6

2 Quick guide 8

2.1 Power switch and keyboard 8

2.2 Measuring ports 9

2.3 Auxiliary ports 10

2.4 Function description 11

2.5 Adjust operating state 13

2.6 Local oscillation mode 13

2.7 Set the basic testing parameter 14

2.8 Filed strength mode setting 15

2.9 Insertion loss mode 15

2.10 Data storage 16

3 User calibration and preparations 17

3.1 Overview 17

3.2 Calibration modes 17

3.3 Calibration before S21 measurement 18

3.4 Calibration before S11 measurement 19

3.5 Reflection standard 20

3.6 Cable Compensation 20

3.7 Using the external bridge 21

4 Common measurement methods 23

4.1 Quick adjustment of duplexer 23

4.2 Antenna measurement 26

4.3 Measuring electric length of cable 29

4.4 Spectrum 30

4.5 Detecting interference source 31

5 Maintenance 33

5.1 How to clean screen, keyboard and ports 33

5.2 Other matters needing attention 33

6 Technical notes 35

6.1 Measuring principle 35

6.2 Charging time and time of endurance 36

6.3 Technical parameters 37

Introduction

KC901M 1

Charger 1

Shoulder Strap 1

KC901M is a multipurpose RF instrument integrating a VNA (vector network
analyzer), spectrum analyzer, field strength meter, and an extra low-frequency signal
source. It can do complete single port vector measurement and 2-ports simple vector
network analyzing.

Main Features

Vector network analyzing up to 9.8GHz
1Hz frequency step
Good accuracy and anti-interference ability
Abundant functions and easy to carry

Main Functions

Transmission measurement (Filter adjustments, measuring amplifiers, verifying
directivity of antennas)

Reflection measurement (Impedance matching network adjustment, antenna
feeding system quality evaluation)

RF source plus an extra audio signal source

Spectrum display and field strength observation (potentially used for inspecting
a radio station’s emission performance, or for searching for the interference sources)

Recommended Applications

The KC901M is mainly used for adjusting various RF circuits, such as filters,
amplifiers, splitters, combiners; testing input/output impedance, evaluating antenna
feeding system and detecting equipment’s signal amplitudes at all levels. It can also
do field strength measurement, which is useful for checking the correct operation of
low powered devices with integrated antennas and when searching for interference
sources etc.

Combining intelligence in the community, KC901M is a well-performing tool to
study RF for hobbyists. In professional situations, it is used in communication
engineering, antenna manufacturing, daily maintenance of broadcast, RF circuits
development and so on. The KC901Mis light, portable, flexible and easy to use
improving work efficiency, and quality.

Acceptance and check

confirm if the package is no damaged before opening it, and then when you
open the package, read the introduction of the user manual carefully and make sure
there are no items missing.

The standard packing includes:

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User manual 1

Please check all the items in the list provided above and make sure that there is
no physical damage to the instrument, check that all the screws are in place and
secure and also check that there is no abnormal sound while shaking it.

After that, connect the charger to the instrument and turn on the instrument to
check that it works within specification. If batteries are in place,press and hold the
power button (POWER, PWR) for 5 seconds to do the start-up check.

Safety Information

KC901M is NOT a device for general consumers, thus the user should have
related professional knowledge in order to benefit from it.

In this user manual,

NOTICE

indicates that it may cause inaccurate testing results or may incur some risk.

Warning

indicates that it may cause harms to the human body, the surroundings, or damages

to the instrument, etcetera.

Please DO NOT use the instrument if it accidentally gets spilled by water or other
liquid, or makes any weird sound while shaking, or when any other obvious abnormal
situation occurs.

Do NOT perform any test with the instrument outdoors during thunderstorm.

Pay attention to the ground connection of the devices under test to avoid
electric shock. Before the connection, equipotential touching must be done by
touching the connectors first to prevent the damages to the instrument or the
equipment due to potential difference engendered between systems.

Keep your eyes on the instrument while charging it. The instrument must be
kept from the inflammables and explosives while is being charged or operated. Do
NOT cover the instrument or the charger in case it overheats.
Be careful of the storage temperature range. Do NOT leave it in the car exposed to
the sun.

Using it in any inappropriate ways is absolutely banned. People embedded with
intrusive electronic equipment should use it with caution. Also think carefully before
use it in hospitals, airports and other sensitive areas.

The maximum battery capacity of KC901M is 60Wh. Choose qualified batteries
for the instrument. Keep the instrument properly according to the installed batteries
characters and be careful of the potential risks of the lithium battery.

Keep it from children. When KC901M is lent to someone,urge the borrower to
read the user manual first and inform him/her the safety information before using it.

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Important Statement

KC901M aligns with the third-party’s technical standards and attains recognition
and certification in industrial design capabilities, while it is NOT a commercialized
product, therefore, it may not satisfy the aesthetical requirements on appearance of
all users. But we always try our best to live up to users’ expectation with our products,
even still, there remains room for improvement. We embrace suggestions and
feedback from all users, so your supports and understanding will be appreciated very
much.
Within the law, KECHUANG and MEASALL will NOT take any responsibility of the loss
which beyond KC901M’s own price in any situations. Meanwhile, we also will NOT
take the responsibility of any direct/indirect loss regarding to time, business,
inconvenience, profit and abuse maintenance etc. The compensations accepted will
be limited to product repair, product return or exchange, and repayment in full price .
We only take responsibility for the product within stipulated guarantee period.

Under no circumstances, do we make any guarantee of the KC901M’s
applicability, reliability and security for uses such as medical care, military and so on.
We do NOT support promises from other dealers.

*Read the technical instruction.
** You are welcome to support our communities: bbs.Kechuang.org, HelloCQ.net.
*** Informal functions
For remote controlling, check our programming manual.

For upgrading, check our software upgrade instruction

Please check if there is a revised version of this user manual, as we don’t release any special
notifications when revisions are made. You are welcome to check and download the latest version
from www.measall.com.
KeChuang Instrument Association is a scientific research community which is hosted by KeChuang
Institute. It’s a department that developed KC901M.
KeChuang Institute has given authority to Sichuan Kexinshe Ltd. Co. to take charge of the production
of KC901M. At the same time, it’s responsible for the Domestic distribution of KC901M.
KeChuang Institute has given authority to Guangdong Deepace Science and Technology Ltd. to take
charge of the international distribution of KC901M.
Except the extra declarations, KeChuang Institute has all copyright of KC901M’s software and
hardware.
The product of the tool chain, the components and its attached firmware, which are supplied by the
thirdpart, are authorized being used by Kexinshe.
The copyright of the operation system is owned by KeChaung Institute.
The “中” logo of KeChuang and the KCSA logo, which are stylized, are the registered trademarks of
KeChuang Institute. KeXinShe is authorized the use of them. “Kexinshe” is the registered trademark
of KeXinShe Ltd.

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Chapter One : Installation Guide

1.1 How to Choose Batteries

1.2 How to Install Batteries

There is no battery pre-installed in KC901M except specifically asked. The batteries
will be installed by either the dealers or users themselves. Supply power with the
power adapter and verify it by starting up the instrument. After making sure the
instrument works properly, Turn off the power and unplug the power adapter, then
you may install the batteries.

Lithium batteries can be used on KC901M. For a single cell, its charging cut-off
voltage is 4.2V, and the discharging cut-off voltage is 2.6V, with voltage rating of

3.6-3.7V. Batteries are connected with two in parallels then the two groups in series.
The power management circuits provide the functions of overcharge protection,
over-discharge protection, balance protection and short-circuit protection.

The battery compartment is suitable to the cylindrical 18650 lithium batteries,
with the diameter of 18mm and the length of 65mm. The batteries must be qualified
with the related standards of the formal factories.

The KC901M can work with two or four batteries, ideally a set of four-batteries
to allow longer operation. The rated charging current of KC901M is 1A. If there are
only two batteries, for single battery, the peak charging current is 1.2A. Peak
discharging current is 1.5A; if there are 4 batteries, charge/discharge load should be
considered and accordingly the peak currents are slightly higher than the ones
mentioned above.

The batteries must be of the same type and should be from the same batch.
Please do NOT mix new and used batteries and if only using two batteries, do NOT
install them in ONE compartment. (See step 4 under Chart 1-2 below) Before
installing the batteries, please make sure that every battery has the same basic
voltage and the differences in the voltages between them is no larger than 50Mv,
otherwise they need equalizing by charge/discharge before being used.

Please take good care of the batteries based on the manual. Usually the low

-temperature resisting batteries can be used only in winter. When the temperature is
over 45 ℃ , since the KC901M’s circuits will generate heat, the batteries set’s

temperature will probably exceed 65℃. In this case, high temperature rated batteries
must be used.

Required tools: one 2mm hexagon screwdriver.

Step 1: Place the instrument flatwise on the desk and take out the two screws
from the bottom. (Chart 1-1)

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Chart 1-1

Step 2: pull the keyboard side of the shell and slide it 2cm out from the bottom
(Chart 1-2). To do it, your fingers must hold the two sides of the shell hard and pull
the RF adapter out at the same time. If it gets stuck, you can knock the bottom on the
lower shell lightly. DO NOT knock it too hard; the maximum sliding distance is 4cm, if
taken beyond this distance,, the inner cables will break.

Chart 1-2

Step 3: lift the upper shell slightly, and then turn it around to the left side.

Step 4: Install the batteries so that the positive poles are pointing toward the RF

adapter. If there are only two batteries being installed, please install them separately
to the most left side and the most right side. (Chart 1-3)

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Step 5: Check the data cable adapter. If there is any deviation and they are not

1.3 How to Mount Shoulder Strap

1.4 How to Carry and Hold

correctly seated, please set them right again.

Step 6: Put the shells back together again using the reverse of the steps above.
Then press the POWER button to turn on the power and then perform a functional
check. If it appears to be functioning correctly, reinstall the screws.

There are both mounting installing holes on the instrument’s upper part and
bottom part (behind RF port). So you can carry the instrument either with the RF port
upward or downward. If you need to carry it around, the strap mounting on the
bottom is recommended.

Unfold the strap and take it out of the plastic fasteners. Then thread it through
back to the mounting points and lock it back tightly in the plastic fasteners.

Chart 1-3 Batteries’ direction and installation steps

Warning

The standard strap is only for the carrying the KC901 during normal use. When
working at height, please take extra measures to avoid the instrument falling and
causing an accident.

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After the strap is adjusted to a suitable length, the user can carry the instrument
with the strap laying over his/her shoulder (such that the instrument will be at the
side next to user’s waist) or it can just worn with the strap around the back of the
neck (then the instrument will be in front of the body). If it needs to be carried
around, hanging it upside down is suggested so that it is in the ready for use when
picked up without the straps in the way. Please shorten the strap before you try to
carry it while running. Be careful that the instrument does not hit your body when
carrying it with the strap laying over on the shoulder.

KC901M is designed to be held with the left hand and be operated with the right
hand. So when you are using while standing, the instrument should be held on its
left-upper part with left hand so that the thumb is in charge of operating the knob.
Also the instrument’s bottom should be held against the belly. The right hand is in
charge of connecting the cables and operating the keyboard.

Using the knob is optional. The user can do all the operations necessary by
operating the keyboard. Button “+”, ”-” instead of using the rotating knob. The
button ENTER can be used as an alternative to pressing the knob. When operating the
instrument using only the keyboard, hold the unit with both hands under display
screen.

KC901M can be fixed on to a working surface by using screws through its strap
holes.

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Chapter Two Quick Guide

Name

Functions

CENT

Setting sweeping central frequency

SPAN

Setting the span width (frequency span)

MODE

Entering function selection. Pressing repeatedly switches between
function selection menu and function menu.

FUNC

Entering system setup and exiting system setup

With the help of the community, the KC901M’s designers have been continuously
striving to make it easy and straight forward to operate the instrument. User who has
only a basic related knowledge can also be familiar with using the KC901M within two
days. Therefore, this user manual is simplified and will not detail the settings of every
function. It only contains some instructions and explanations for some special parts.

2.1 Power switch and Keyboard

Chart 2-1 shows the layout of keyboard. Press the power button (POWER, PWR),
which is on the bottom left, and hold it for 0.5 seconds. After starting up the
instrument, instrument it displays the same information as the last time it was
operated. The menu displays related settings in its current mode.

Chart 2-1: The keyboard’s Layout

Chart of Keyboard’s primary functions

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STOP/RUN

Stops sweeping, starts sweeping (Toggles between each mode)

+、-

Same as function as rotating knob, but the step is larger than the knob.

MARK

Enters into the cursor function menu (and activates knob for marker
control)

AMP

Amplitude menu allows adjusting of the reference level, trajectory
position, the range of the signal source function as well as the vertical
extent in VSWR test.

POWER

Power switch

SHIFT

Allows selection of the secondary functions

Chart 2-1

Key Combination

Functions to use

SHIFT+CENT

Setting the beginning(start) frequency

SHIFT+SPAN

Setting the ending(stop) frequency

SHIFT+LOCAL

Disconnecting to the computer and forcibly switching to the
local operation

SHIFT+FUNC

Resetting to defaults

SHIFT+STOP/RUN

Switching to the single step sweeping. In this mode, press
STOP/RUN once, sweep once.

SHIFT+1

Saving the data to the storage card

SHIFT+2

Read the curves and settings from the storage card

SHIFT+3

Self-defining the file names after saving the data into the storage
card

SHIFT+4

Adjusting the screen luminance

SHIFT+5

Adjusting the RF output range

SHIFT+6

On/off the key tone

SHIFT+.

Saving the current user calibration data

SHIFT+0

Reading the user calibration data

SHIFT+ENTER

Locking the keyboard and knob to prevent accidental
operation

CENT and SPAN button function can be set in “Frequency control” which is in the
FUNC menu.

Chart of Keyboard’s secondary functions

Chart 2-2

2.2 Measuring Ports

There are three signal ports in KC901M. Two external RF ports (50 ohms), one AF
port (1Kohm). The far right one is Port 1, the input/output port for testing spectrum
and reflection. The far left one is Ports 2, generally the output port for transmission
measurement and the output of RF signal source. Inside the instrument, there is

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another RF port already connected to a standard load; the standard load is
replaceable.

In other files, as shown in chart 2-4, the ports from left to right are named Port 2,
Port 3 and Port 1.

The N type measuring port has a precise surface which needs to be protected,
especially the S11 port from the right side. Use only quality connectors and always
check before connecting. If the core needle is sticking out too long or bent, fix it
before making the connection. However, it’s not necessary to connect an adaptor just
for protecting the ports. Extra adaptors will worsen the accuracy.

The designed lifetime of RF ports is 500 times plug in/pull out. Ports’ aging has
certain influence on the accuracy of the vector measurement. Please replace the port
connector when the old one is out of its useful lifetime.

Chart 2-4 Signal ports on top

2.3 Auxiliary Ports

There are four ports at the right side as the following picture shows. From left to
right: TF card slot, RJ45 Ethernet port, power input jack, and USB port. (Shown as
Chart 2-5)

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Chart 2-5 Ancillary ports on the right side

Attention:

While performing the transmission measurement, the signals released flow in the

opposite direction to those in reflection measurement, which is different from usual

network analyzer designs (including the KC901S). This means, after testing S11, to

test S21, you must switch the two ports according to the indications on the device.

2.4 Function description

Six basic functions of KC901M

Reflection test (S11)
Transmission test (S21)
Spectrum (SPEC)
Field strength (FIELD)
RF signal source (RF SOURCE)
Audio signal source (AF SOURCE)

MODE button is for function selection. Function can be switched by pressing
MODE repeatedly. In most situations, user can switch back to the function
menu/function selection menu by just pressing MODE, it can be used like a HOME
button

Reflection test (S11)

The typical application of reflection test (S11) is to test antenna’s VSWR and
impedance. For this function, please use the port on the righthand side. (See Chart
2-4)

Reflection is measured in vector. It has various ways to display which can be
chosen through the FORMAT menu. When showing Smith chart and the impedance,
the soft menu from the second left can provide more options for display.

Access: Press MODE and then choose the item of reflection test (S11) in the
menu.

Transmission test (S21)

The typical application of transmission measurement (S21/12) is to test the filter
and the amplitude-frequency characteristic chart. For this, both two N type RF ports
need to be used. Signals are output from the instrument’s left side port and input into
the right side port.

Access: MODE and then choose item S21.

Insertion Loss Measurement is a transmission measurement at single frequency

point that can respond so quickly enough that it allows users to adjust the Device

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Under Test (DUT) more efficiently. It can also be used for accurate filter adjustment as
well as measuring the antenna gain.

In order to align with the operation of other types of devices, turn-on/off setting
of insertion loss measurement function has been placed in the field strength mode
menu.

Access: press MODE, choose FIELD in the menu, then choose Insertion. You will
see that “GEN ON” on the right down of the screen. See further information on field
strength functions information after the spectrum function below.

Spectrum (SPEC)

Spectrum mode (SPEC) is typically used for monitoring frequency occupation and
interference, but can be used for testing RF circuits as well with suitable attenuation.
When connecting to the KC-R100 directional antenna, SPEC can even detect hidden
emission sources. (Spectrum function uses the right-hand-side port)

Access: Press MODE and then choose SPEC in the menu.

Field strength (FIELD)

Field Strength mode (FIELD) is for testing field strength and signal coverage and
also detecting the amplitude of RF signals in circuits. Due to DC isolation being
already installed, users can connect probes to test signals without affecting the DC
bias in receivers and transmitters directly. However please be careful of impedance’s
match so that the measurement does not affect the normal operation of the
equipment under test. Also it is necessary to take safety measures such as adding
extra attenuation to protect the attenuator and the DC block which are concatenated
with KC901M when measuring transmitters. Proficient users can use field strength
mode to quickly judge if radio station’s emission is strong enough. For this mode,
please use the port on the right side.

Access: Press MODE then choose FIELD in the menu.

RF signal source (RF SOURCE)

RF Signal Source (RF SOURCE) is for producing a signal in mW range, its typical
application is to transmit a weak signal to check radio receivers sensitivity on a
frequency from a short distance away. A skillful operator would also find these low
level radiated signals of great value. An external attenuator can be added to extend
the uses of signal source when the RF generator port is directly connected to other
equipment.

The RF signal source’s output level can be setting through internal output
attenuator. Instrument’s output attenuator can also be used as an amplitude
modulator generating ASK signal. If the output attenuator is already used for setting
output power, the modulation depth is limited by output attenuation level. The bigger
the attenuation is, the smaller the modulation level which can be used will be.

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In RF signal source mode, please use the N-port on the left side. The RF generator
has the option of having its output selected as either Port2 or Port1.

Access: Press MODE and then NEXT, finally choose RF SOURCE in the menu.

Audio signal source (AF SOURCE)

Audio Signal Source(AF SOURCE) is for producing a low-frequency voltage signal.
its typical application is to adjust the audio signal paths in devices. Since the audio
signal source can produce a steady output up to 50MHz with various modulation, it
can also be used for adjusting RF circuits under 50MHz.

The Audio signal source actually can be set to a very high frequency (performance
can’t be guaranteed). Assisted by the under-sampling output, it can also be used for
adjusting radio station’s sensitivity and so on. The AF generator has the option of its
output being selected as the central BNC AF gen output (1Kohm), Port2 or Port1
(both 50 ohms).

Access: Press MODE and then choose NEXT, finally choose AF SOURCE in the
menu.

2.5 Adjust Operation State

On power-on, under the default setting the device will automatically sweep once,

and then turn STOP. Thereinafter, you must restart it by pressing RUN/STOP, then it
keeps sweeping until you push the same to stop. By clicking SHIFT first and then press
RUN/STOP, a secondary function of the RUN/STOP button is activated (shown in the

screen the sign “ ”); and this is for one-time sweep. In this mode, each time you
press RUN/STOP the device will run once only. Re-press SHIFT + RUN/STOP to
terminate this mode.

Single sweeping mode. Instrument sweeps only once with each RUN/STOP

press.

continuous sweeping mode. Instrument will do the constant sweeping. In

the single sweep mode, this sign will also be shown while sweeping.

Stop sweeping. RF circuit’s power will be cut entirely.

If the main setting parameters are changed when not sweeping, instrument will

scan once automatically.

NOTice:

Since there is no warm-up, the result will be less precise in the single sweeping
mode and thus it is more suitable for qualitative analysis. To collect more accurate
data, instrument must be set to “continuous sweeping mode”.

2.6 Local Oscillation Mode

There is a Local oscillation mode in each of the following modes: SPEC, S21 and
FIELD. This function is for judging signal imaging.

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LowLo: Low local oscillation. The LO frequency is lower than the test frequency.
The image interference is from the low frequency side.

HighLo: High local oscillation. The LO frequency is higher than the test frequency.
The image interference is from the high frequency side.

If there is a signal showing in the same position on the screen whether in LowLo
mode or HighLo mode, this signal is probably a truly existed signal. On the contrary, if
a signal disappears in whichever mode, it is probably fake. If it shows in LowLo mode
but disappears in HighLo mode, the real frequency probably is 219.3MHz less than
the one that is shown. If it shows in HighLo mode but disappears in LowLo mode, the
real frequency probably is 219.3MHz more than the one that is shown.

When the frequency is lower than 200MHz, the local oscillation setting is invalid.
In this case, image interference can be filtered through low-pass filter.

NOTice

The factory calibrations of spectrum, transmission and field strength modes are
done in HighLo mode. The test may be inaccurate under LowLo mode.

2.7 Basic Testing Parameters Setting

To set the central frequency, press CENT first, then enter the frequence on the
number pad. If the desired frequency is near the current frequency setting, user
might use the wheel knob or press “+” “-”.

To set the sweeping width, press SPAN.

To set the start frequency (START), use the combined key SHIFT+CENT.

To set the stop frequency (STOP), use the combined key SHIFT+SPAN.

If you are used to enter the frequency with start/stop frequency, you can set the
frequency control item as “START/STOP” in FUNC menu.

To adjust the reference level, press AMP or rotate the wheel knob clockwise or
counterclockwise, or simply use the “+” and “－” buttons.

While testing VSWR, button AMP is for adjusting the amplitude display division.
Pressing it repeatedly can switch the range among large, middle and small.

Sweeping point’s setting is in the FUNC menu, shown as SWEEP POINT. it as
450 points in most situation and it’s not necessary to change it in usual cases.
Instrument will choose the suitable frequency step (STEP) automatically according to
the sweeping width.

Sweeping speed can be set in FUNC menu with 3 levels: fast, middle and slow.
Usually the middle level is adopted. The fast level can increase efficiency by
shortening the sweep time, while reducing accuracy rate; if this is the case, there will
be a “*” shown on top right corner of the screen to notify user that the result is not
accurate.
The RBW of S11 and S21 need to be set in the FUNC menu. The smaller RBW is, the
slower the instrument sweeps. Normally factory calibration is executed on 10KHz

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RBW, so it is recommended to set RBW as 10KHz unless specially required in other
situations.

In the menu of S21, item (dB/div) can be used for switching the range of
ordinate.

2.8 Field Strength Mode Settings

Field strength mode is measuring the level of input port signal. Field strength’s
value derives from the calculation of input level and the antenna’s coefficient.
Antenna’s coefficient is mainly related to antenna’s gain and frequency. So make sure
that the instrument gets the antenna’s gain in order to obtain the accurate field
strength.

After enter field strength mode (FIELD), there is an item (ANT GAIN) in the menu.
Press the button and choose the sign with “+/-” in the menu, next enter the antenna’s
gain on the number keyboard.
The update speed of the number display can be set in 3 levels: FAST, MEDIUM and
SLOW. MEDIUM is recommended. The update speed of the scale-meter will not be
influenced by this setting, but for observing the transient strength change of signal
strength.

Warning

KC901M is a network analyzer, so there is no protection for local oscillation’s
leak. If used for observing the spectrum or field strength, there must be local
oscillation signal flow into the receiving antenna and its strength degree can reach

-10dBm. Its frequency is at 109.65MHz plus or minus the receiving frequency. User
should estimate the consequences and if needed, use Po. ATT function of internal
attenuator or avoid the interfering frequency points by setting local oscillation as
well as adding a band-pass filter.

2.9 Insertion Loss Mode

Insertion loss test is actually a single point S21 measurement.

Firstly, enter field strength mode, and then choose “Insertion” on the bottom
right corner on the screen; then there will occur a “GEN ON” sign. The data on the left
side of the screen is the absolute level value, while the data on the right is the relative
level. To calibrate, connect the testing cable directly to each RF port, and then choose
AUTO CAL in the menu. After calibrating, connect the device under the test to the
testing cable. Reading at the right is insertion loss.

2.10 Data Saving

To save the data, insert a micro SD (TF) card into the instrument.

In test function, press combined key SHIFT+1 to save the current screenshot, and
the test results and settings as a chart.

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The file will be automatically named by system. If you want rename file use the

(1) The sweep speed shall better be MEDIUM, since HIGH level is only applicable

(2) Select “INT” for both FREQ REF and TRIGER

(3) Select “INT” for S11 BRIDGE for a built-in bridge

combined key SHIFT+3.

While connecting the instrument to PC via USB, the instrument is detected as a
USB flash drive. In this case, the SD card is already taken over by the PC, therefore
when connecting to PC, data can’t be saved.

In S11, if you need to save the files of S1P format or all original testing points,
you need to save it in the Smith chart mode.

2.11 More Information about the System Settings

Normally the FUNC button pops you into the operating surface, where you can
further access the Advanced System Setting Surface (ASSS) with the combined key
SHIFT +7 . In the ASSS the parameters must be examined to be correct to achieve
measurement validity. You can reset all parameters to the defaults via the Factory
Reset function. But be
Sweep point 450 is recommended to boost up the sweep speed

for qualitative analysis because of the louder noises and data deviation under
this mode; and LOW level is ideal for enhancing accuracy though, it requires
minor calibration manually.

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Chapter 3 User Calibration

and Preparation before Measurement

3.1 Overview

KC901M has been calibrated on its ports at factory already. Due to various
reasons, there may have deviations where the displayed curves may appear drifting
and not necessary reflect the exact situations in some cases. Yet in common
engineering applications, the deviations would not tarnish judgments thus there is no
need to conduct another calibration.
In terms of measurement, cables and adapters are commonly used but these
accessories will induce loss and phase shift. Furthermore, its performance is subject
to changes such as temperature and time, accompanied with drift. Under the
circumstances which interferences could seriously impact the results of the measure,
the instrument would need an immediate calibration.

Calibration data is only valid if measuring DUT under the same conditions (cables,
adaptors, temperature, analyzing bandwidth and sweeping speed etc.) as performing
the calibration; or else new errors will occur when any condition changes. In a word,
calibration conditions should be as close as it can be the actual situation of the test.

Try to reduce the frequency of changing different adaptors during testing,
particularly it’s not recommended to put on an extra adaptor for whatever reason.

3.2 Calibration Modes

There are three kinds of calibrations in KC901M, factory calibration, system
calibration and user calibration.

Factory calibration: Instrument has a high-density full-band calibration, using
scaling algorithm to conduct more precise interpolation. The factory calibration is
saved into the instrument permanently; users cannot reset it or use it directly. But it
can override the system calibration by restoring factory settings.

System calibration: after the instrument comes out from the factory, the data of
system calibration is the same as factory calibration. System calibration can be used
directly and recalibrated by the users. It avoids further calibration since the System
Calibration in that in whichever frequency the device will execute sbasic error
correction. If it runs the “factory reset”, the system calibration which is set by user will
be abandoned and the system calibration data will be the same as the factory
calibration.

User calibration: it can be set by user anytime. This calibration will do the
correction to every data point according to the actual setting. There will not be

- 17 -

interpolation errors. Therefore, its accuracy is higher than the factory calibration and
the system calibration. User calibration is only effective for the set frequency. If the
setting parameters are changed, the calibration data will be useless though, it will be
saved temporarily lest we go back to the last setting parameters; in this case the
previous calibration data is still valid.

Calibration procedure

Under the S11 and S21 display modes, every menu on the very right side has
“CAL Select”. It’s for switching among system calibration, user calibration and shut
down calibration.

To start out the user calibration, choose “RE CAL”.

In FUNC menu, access into the system calibration with the combined key
SHIFT+7 .

When entering the calibration interface, the surface will pop up specific
operating methods. When carrying out the S11 calibration, users can SKIP the loading
procedure (LOAD).
The electric length of calibration module’s electric length parameters must be preset
first in FUNC menu.

3.3 Calibration before S21 Measurement

As long as within the dynamic range, series attenuators (above 6dB) are highly
recommended to minimize the errors.
If the DUT is small and light, you can connect the DUT’s port to the instrument
directly, although it is not a good practice. In this case, only one RF cable is needed for
a complete testing system. If the DUT is too big and heavy or the adaptor does not
match, then you need two RF cables.

Chart 3-1A: Connect with one cable in calibration

- 18 -

You can use either one or two cables to execute the calibration. As for using one
cable, simply joint the two ends of the cable to the two ports respectively (Chart
3-1A). As for using two, firstly use a thru-connector with a known electric length to
connect the two cables, and next joint the rest of the two ends respectively to the
two ports (Chart3-1B). There you can calibrate the instrument on your own.

If there are many cables which are connected in series in different places in one
system, user shall better connect all of them together in series then do the
calibration.

When testing power amplifier, the power amplifier’s output should connect in
series with an attenuator to avoid excessive RF power that will damage the
instrument. If the amplifier is a small -signal amplifier, connect the attenuator to its
input port otherwise the drive signal being too strong; moreover before
implementation, all the attenuators and cables should be connected in series to do
the calibration.

To start the user calibration, choose “Re CAL” in the function menu and then
follow the guilds.

Chart 3-1B: Connect two cables in calibration

Set the parameters of the calibration kit (or other adaptors whose electric
lengths are known) in the FUNC menu. Pre-setting the calibration kit’s electric length
enables the instrument to compensate calibration kit’s phase shift automatically. For
the testing system where there are several cables and adapters, in the FUNC menu,
the thru adaptor’s electric length should be set as the sum of the adapters’ electric
lengths which will later be removed from the actual test.

To change the frequency after the calibration, the instrument will select system
calibration automatically.

- 19 -

3.4 Calibration before S11 Measurement

Function S11 has multiple display modes yet it needs calibration once only, given
that the calibration parameters can be used in all modes.

User calibration should be done in the following situations:

Verifying important devices (e.g. antennas for broadcasting and TV station).

DUT fails to directly connect to the instrument, where necessitates extra cables.

After calibration, test if the curve of open and load are shown normally. If there
are some obvious errors, redo the calibration. In VSWR mode, curves in an open
circuit should be over than 10; when connecting to the load, it should be under 1.2.

NOTice

Executing calibration at the far-end of the external cables, under the condition
which the external cables’ electric lengths exceed one half of the wave length of the
frequency (STEP), user needs to increase the sweeping points (or reduce SPAN)
before the calibration to avert the phase aliasing. For example, STEP 3MHz converting
to wave length equals 100m. The external cable must be less than 35 meter (Electric
length = cable’s actual length/speed factor).

Choose “Re CAL” in mode S11 and then follow the operation tips.

DUT can sometimes be a printed circuit, or a device which cannot be connected
with a coaxial connector, therefore users need to strip off testing cable’s end and then
solder it on the DUT. In situations of this kind, user can do the open-short calibration
before connect the DUT. Operating the open-short calibration, users should solder
coaxial cables’ core wires on the shielding layer; in an open circuit, users should
separate the cables and hang them in the air. When the instrument is loading (LOAD),
choose “Skip” in the soft menu.

3.5 Reflection Calibrator

S11 abides by SOL calibration, in which the three capital letters respectively
represent 3 types of calibrators: short, open and load.
KC951011/KC951012 is the SOL calibrator that we (Kexinshe) produced. Users can
also use other proper calibrators, but keep in mind that the terminal effect of the
chosen calibrators must be small enough since there is no compensation for KC901M
(non-commercial version). KC951011’s nominal electric length is 5.26mm and
KC951012’s one is 0. If a user chooses other standard, he/she needs to input the
value of the actual electric length in the FUNC interface.
To attach the calibrator tightly with instrument, clamp it hard with the thumb and the
index finger. If using a torque spanner, the torque should better be 135M.cm.
Calibrator are expensive accessories that should be taken good care of and better be
scrutinized from time to time. Check the adaptors before calibration to prevent
unexpected damages to the calibrator.

- 20 -

3.6 Cable Compensation (Extension)

In order to connect the instrument and DUT, usually we can calibrate on the end
of the RF cables; but in some restricted occasions, users can either appeal to the
system calibration or just calibrate it by manual, thanks to the compensation function
that erases the influences by the cables on measurement. Of course the second
method brings about lower accuracy rate than the first method does.

Firstly, strictly follow the steps shown in Section 4.3 to test the exact electrical
length of the cable. If the cable’s velocity coefficient is already known, electric length
can derive from calculating cable’s mechanical length. But it will be less accurate than
actually measuring it.

When the cable cannot be disconnected from the antenna easily, users can again
turn to Section 4.3 to test the electric length. Choose those frequency bands whose
phase variation tendency is steady, meanwhile phase-frequency characteristics curve
should be rather straight. In this way, usually the tested electric length will extend to
antenna’s feed point, which is a more effective way to do the calibration than
adjusting the antenna. This method also applies to the occasion where calibration is
executed on the end of the feeder in that by doing so, users can maintain the phase
plane extended to feed point.

Press FUNC to enter system setting interface. There is an item” Cable data”.
Enter the testing result into “Cable Length”.

“Cable attenuation” means antenna’s single attenuation in “Cable frequency”.

The best way to measure cable attenuation is using S21. But sometimes in reality,
users may be set back from performing the calibration on the other side, in other
word, fail to do the S21 measurement. There we need to enter the data from the
cable’s factory. Of course we can also appeal to S11 to measure it in far-end open
circuit: if there are fluctuations in the curve, take the wave crest of less attenuation
near the final-expected frequency band. Pay attention that the reading number
should be divided by 2. When the attenuation is unsure, set it as 0.

Once “Cable data” is set, instrument will try to cancel the cable influence with it.
After the measurement is done, reset the parameters in time to prevent mistakes in
future use.

Cable parameter is also effective in S21 measurement.

3.7 Using the External Bridge

Access the “Advanced Settings” via combined keys SHIFT + 7 in the FUNC menu,

and make sure if the S11 BRIDGE is on EXT mode. Then the input port should go with
the left port of the instrument (Port 2), the output port should go with the right one
(Port 1). In this situation, attenuators in series are generally recommended.
Additionally, S11 calibration must be done before measurement.
Higher accuracy rate can be achieved through an external bridge with better
configuration than an internal bridge.

3.8 Necessary Preparation

- 21 -

3.8.1 Check battery status before going outdoors, particularly when working
outdoors for long hours, bring the charger as well (a external battery pack is more
helpful in the absence of socket). A shortcut to test if there remains enough power,
run the instrument and read the voltmeter; if the meter shows a voltage over 8.0 V, it
has at least half of the power left for use.

3.8.2 Be cautious of the instrument and prevent exposure to water or rains when
working outdoors. It is better be safeguarded in a waterproof Pelican case.

3.8.3 When it may be necessary to measure an amplifier or transmitter, prepare
enough attenuators. When the tested signal is suspected to be over the instrument’s
limit, user must connect the attenuators in series.

3.8.4 When testing in places where antennas may work intensively, such as
broadcast and television tower, to ensure interference will not have much effect on

the result, it is advised to test the coupled power of the antenna beforehand with the
terminal power meter, and the meter should indicate lower than 0.1W. Besides, when

other antennas are working, it will engender powerful emissions that may couple
together, which will definitely do harm to the instrument.

3.8.5 When testing antennas near the high voltage power line or a substation,
please check that the coupled voltage on the port which under test with ac voltmeter.
The induced peak voltage shouldn’t be over 15V. Also coaxial cable’s shielding layer
should be grounded nearby.

3.8.6 If using a probe to measure RF signal on circuit board, it is imperative to
connect the external shielding layer of the cable with circuit board’s ground together,
or else it probably will break KC901M.

3.8.7 Instrument can measure passive devices while it’s charging. But user
should avoid using it on active devices in the same situation. If user insists on doing so,
please connect the ground of KC901M (the external layer of the coaxial connector) to
the ground of the DUT in equipotential connection to prevent the damages due to
the voltage difference between two.

3.8.8 If user needs to test at somewhere high, prepare enough firm safety ropes
and packing bags. Also set warning zone under the tower.

- 22 -

Chapter Four Common Measurement Methods

4.1 Quick Adjustment of Duplexer

Duplexer is an important part of a repeater. Its insertion loss and isolation ratio
are related to the performance of the repeater. In frequency band which is used
commonly, KC901M can provide an operation range better than 95dB. User can
adjust the duplexer into the best state under its monitoring.

Prepared accessories: a 50Ω load, 2 RF cables, necessary RF adaptors

Fixing KC901M on the workbench

tools: a socket spanner with a center hole, screwdrivers. If it’s possible, fix the
duplexer which is under the test on the workbench.

Special settings: In the beginning of the adjustment, user can use middle speed
or high speed (FUNC, Speed). When doing the fine-tuning to the trap frequency point,
user should adjust to Low Speed; or the insertion loss mode can work as well.

Take band trap theory’s six-cavity duplexer as an example to introduce the
adjusting steps.

Set KC901M to S21 and then set its center and span so that the frequency range
covers the original and the new frequencies of the duplexer. AMP can be set as 0dB or
+10dB (AMP and ordinate range can be switched according to the curve’s position.).
After turning on the system calibration, move mark1 and mark2 nearby duplexer’s
new receiver frequency and transmitter frequency.
To begin with, measure the insertion loss of the RF cable (S21); slightly shake the
cable and adaptor, and see if the curve shakes as well: if it does, double check the
contact point. Cable’s insertion loss should be neglectably small and be steady as well.
Choose a cable of adequate quality. User can hang the cable in the air to check the
position of instrument’s noise floor. In 450MHz, it should be at least up to -90dB
though, better below -100dB.

Clean up the socket of the duplexer, and then connect one of the instrument’s
RF port to duplexer’s TX input port (usually noted as high). After that, connect
instrument’s another port to duplexer’s ANT (antenna) port. Finally, connect the
dummy load to the remaining RX port (usually noted as low)(Chart 4-1).

- 23 -

Chart 4-1: Example for connection method of duplexer measurement

Adjust the three screws nearest to the TX port (the first three on the left in
Chart4-1) until the dip point moves to Mark1 (M1) (Chart4-2). Fine-tune the screws
step by step meanwhile monitor M1’s S reading till it makes to the minimum negative
number. Normally it can reach -60dB. Right now, M1 indicates the insulation of the
HIGH side, and mark2 (M2) indicates the insertion loss of HIGH side.

Connect KC901M’s output port to duplexer’s ANT port, and then connect the
input port to the RX port and the dummy load to the TX port. Adjust the three screws
nearest to the RX port (the last three on the right in Chart4-1) until the dip point
moves to M2 (Chart4-2). Fine-tune these three screws from left to right one by one
repeatedly, at the same time, monitor M2’s S reading till it probes to the minimum
negative number. Also generally, it can reach -60dB.

Adjust the central frequency and sweeping span to zoom in the new curve. Then
adjust the positions of maker1 and marker 2. Finally connect the testing cables with a
thru-coupling to perform user calibration.

Then connect instrument’s output port to duplexer’s TX port, the input port to
the ANT port and the dummy load to RX port. Fine-tune the three screws from left to
right repeatedly till the M1’s S reaches the minimum. In normal situation it should be

- 24 -

lower than -70dB. The derived S-parameter of M2 is the duplexer’s insertion loss to
the transmit signal.

Chart 4-2: Typical curve of duplexer’s LOW side, uncompensated cable loss

To get the insertion loss of the duplexer to the receiving signal, connect the
output port to ANT port, the input port to RX port and the dummy load to TX port.
After that, fine-tune the three screws on the RX side to get to M2’s minimum,
commonly lower than -70dB. There we get the S-parameter of M1, which is the
insertion loss.

Switch the LO (Local Oscillation) mode, compare the minimum value of each curve,
and find out the lowest among. When adjusting both sides of the duplexer, different
OSL modes may need to be used.

Some duplexers’ parameters of both sides can influence each other. In this case,

user may need to do the steps above again till the attenuation parameter is up to

-70dB.

Do not make the notch curve of the duplexer too sharp pointed at the bottom.
Through reducing the SPAN to 1MHz, observe the curve’s bottom: it should be more
then 100KHz wide. If the curve is too sharp, its tip may drift out of the used frequency
once temperature or the matching of antennas has changed.

When there is conflict between the insertion loss and the attenuation, consider
the attenuation at RX side first. Properly lower repeater’s transmission power to lower
the demand of isolation. In this case, keep in mind that “adjust TX toward inside,
adjust RX toward outside” to try to keep the balance between insertion loss and
isolation.

For coupling level, user can adjust the coupling bolt with the duplexer which is
adjusted by the screws. The other adjusting screws can be replaced with the longer

- 25 -

ones if necessary. If the screws need to get inside very deep, duplexer’s Q value will
reduce. If needed, user can lengthen solenoid by taking apart the duplexer.

If the insertion loss can’t be reduced to a reasonable level, user might consider
using S11 (connect the dummy load to the untested port and it’s not preferred to
connect it to instrument’s port) to try different adjustments. Also balance it with
other parameters and make SWR stay within 1.5.

During the adjustment, user should lock the screw to fix the parameters.

NOTice

Port matching has a great influence on duplexer’s attenuation. There will be
some tiny differences of the results by using different instruments. There also will be
differences after changing the connections between instrument and duplexer. There
are differences too for different repeaters and antennas’ impedance which may cause
gap between its actual performance and the expected performance. In the initial
testing, after putting the repeater in, users should be accumulating operating
experiences from each actual performance .

Concatenate the attenuator (about 10dB) with instrument’s input port to
improve the matching. Increase the output attenuation (SHIFT+Po. ATT) to 10dB.

4.2 Antenna Measurement

WARNING

The maximum output generated from the output port of KC901M is
10dBm(10mW). The output will be transmitted to the air via the antenna during
testing. To diminish the transmission, users can increase the output attenuation
(Po.ATT). A recalibration (Re CAL) is imperative in this case.

4.2.1 SWR Measurement

When measuring SWR, set the instrument to S11 and select the Format as VSWR.
Connect the antenna to Port 1, Using adapter if necessary. User must stay away from
the antenna after setting the center and span.

Antenna’s standing wave ratio is related with the field environment. So users
should choose a capacious open-air, such as the roof. The cable should be as short as
it can be; if the RF cable is too long, disconnect the end from the antenna, and then
do the user calibration at the end of cable.

The 13.56 MHz antenna, which RFID usually uses, almost can’t connect to the
instrument directly. In this case, users can make a small ring-type antenna by
themselves to measure its SWR. When leaning that small antenna close to the RFID
antenna, the standing wave will change. This gives valuable experiences for judging
the performance of the tested antenna as the standing wave changes.

4.2.2 Cable canceling

When measuring antennas, users may not be able to calibrate on the antenna’s
port due to the limitation of the field environment, therefore, there exists the

- 26 -

influences from the coax on the result. In such cases, users can “wipe out” the cable
by inputting the cable’s length into the instrument to get the antenna’s RF
parameters.

There are two items in FUNC menu, which are “Cable Length” and “Cable Loss”.
Cable length is the actual length of the cable divided by the velocity coefficient. With
cable length, cable loss can be predicted according to the loss per unit length which is
provided by cable technical manual.

Both two items above are the one -way -travel parameters.

The operation of cable canceling is only suitable on low frequency, for instance,
under 30MHz. Thus as long as permitted, users are highly suggested to do the user
calibration on the end of the cable so that the instrument can remove the cable’s
influences precisely.

4.2.3 Antenna Impedance Measurement

KC901M can calculate antenna’s impedance by testing RF signal, amplitude
differences of reflection signal and the phase differences. Since amplitude and phase
differences are related with the feeder line, the user calibration must be performed
on the end of the feeder line unless the antenna connects to instrument directly.

As for the antenna based of the PCB, if there is no coaxial interface, users can
disconnect the antenna from the PCB, and then connect the thin coaxial cable to the
instrument. Perform calibration before any measurement. Follow the instruction by
the screen to operate an open/short circuit at the end of the coaxial cable accordingly.
Then skip the load calibration (SKIP).

Antenna’s installation environment has a great impact on antenna’s impedance.
For the sake of a more accurate measurement, make sure the antenna system setup
is as close to the application environment as possible. Antennas installed on devices
such as handheld device and routers are integrated with the devices’ metallic
conductive casing, thus they should be tested with the case. For example, to test the
antenna of the router, the router ant’s host device case should be tested together,
and the original coax need to be disconnected from router’s PCB for the antenna. The
end of the testing cable, which is near the antenna, needs to go through the toroid
ring. During the calibration, make sure that this cable is included.

Under the low frequency, if it’s not able to do the calibration on the cable, user
can set cable length in FUNC menu to remove its influence. But it is not applicable to
the occasion when the frequency is relatively high (for example, 2400MHz).

4.2.4 Simple Measurement of Antenna’s Gain and Antenna Pattern

KC901M can test antenna’s horizontal pattern or the front-to-back ratio with S21
(or insertion loss) function with another set of antenna; it can even test the antenna
gain adding one more set of antenna whose gain is known.

Measurement environment: RF anechoic Chamber or standard measurement
site. For engineering measurement, choose somewhere open-air and flat, with the

- 27 -

size more than 20 times of the wave length; generally the flat roof is acceptable to
test antennas whose frequency bands are over UHF.

Equipment: Two antenna stands, one has a turntable on the top. Antenna stands’
heights should correspond with the functional design of the antenna, normally it
should be larger than two operating wavelengths. The distance between the two
stands should be longer than 10 times of the operating wavelength (it is also
acceptable a shorter distance when testing antennas whose operating wavelengths
are exceptionally long, like short-wave antenna). Additionally, to remove the effects of
ground reflection, execute multiple testing at various distances so as to obtain the
average value among the results. Prepare a cable long enough to fit in the distance
between the stands, also allow a distance (between the operator and the instrument)
of at least 10 times of the wavelengths. Besides a tested antenna, a directional
antenna may be needed. To test the antenna gain, prepare another reference
antenna whose gain is already known.

Method: install the testing antenna and the antenna under test on the stand
(Chart 4-3). Testing antenna’s main lobe should align with the antenna under test. In
specific, the first step is to align the under-the -test antenna’s certain direction (a
predicted main-lobe direction or just mark a direction) with the testing antenna.
Secondly, set the instrument to mode S21 and enter the testing frequency. Commonly
choose a smaller span, 1MHz for example. Perform the user calibration in S21 mode
to make the curve return to zero. Rotate the under-the-test antenna within a certain
angle and record the corresponding S -parameters (dB) of every angle. Finally, mark
the points on the angle-gain coordinate graph to get the directivity diagram of the
under-the-test antenna.

The measurement mentioned above can also be done in insertion loss mode.
Firstly, enter into the FIELD mode and choose Insertion to start the insertion
measurement. Then press Auto CAL to make the insertion reading return to zero. Its
insertion reading shares the same meaning with the S -parameter in S21.

Chart 4-3: Measuring Antenna Gain in an Open Field

- 28 -

During the measurement, every measurement data can be saved by using the
combined key SHIFT+1 which is for further analysis. To be more user-friendly, KC901M
will name the files automatically and chronologically. Alternatively users can rename
the file as saving with the combined key SHIFT+3.

Before measuring the testing antenna gain, install the reference antenna (with
known gain) on the stand of the under-the-test antenna. Afterwards, adjust the
orientations of the reference antenna and the testing antenna to aim (make the
reference antenna aligns the under-the-test antenna according to the gain orientation
which is already given). Then do the user calibration in S21 mode and keep the setting
parameters of the instrument. Then replace the reference antenna with the
under-the-test antenna, and test and record the S -parameters in every different
angle. There derives the antenna gain in different angles by the summing up the
tested parameter and the gain of the reference antenna.

Repeat the steps above if you need to test the directivity diagrams and gains in
different frequencies.

Frequency can’t be changed during the test, otherwise user calibration will be
useless and the data will also be invalid. Meanwhile the operator should keep a far
distance from the antenna especially when reading the meter .

When using two pc of KC901M, they can make a scalar network testing system of
single frequency point by setting one of KC901Ms in signal source and another one in
FIELD mode. This system can be used when the two antennas are miles away from
each other. One of the KC901M, which is used for emission, can also be replaced by a
transmitter that has a steady power level. Since the isolation in this way is better than
the internal insolation of a single instrument, it can satisfy some testing applications
which need a large dynamic range. Vice versa, if an operator needs a larger dynamic
range to do other S21 tests, he/she can use a PC to control two pc of KC901M at the
same time).

4.3 Measuring Electric Length of Transmission Line

When the transmission line’s end is in open circuit or short circuit, user can use
KC901M to measure its electric length. In mode S11, adjust it into PHASE display and
take the part of the curve which is smooth and obviously periodical. Then measure
the frequency difference length (Δλ) after the phase rolled one circumference (the
difference between two cursors’ frequencies is nearly 0°N) and divide it by 2 so as to
obtain the electric length of the transmission line. After it, you can get the electric
length of the transmission line. Of course, user can also measure the frequency
difference length after the phase shifts 180°N .Then divide it with 4 to get the result
directly, or try to get the result by measuring two frequency difference length after
two 360°N.

User can also save the data first and then get the group delay by getting the
derivation of the phase on PC to work out the electric length. In this case, user should
choose the smaller SPAN or many sweeping points to avoid phase aliasing.

- 29 -

Take the SPAN which is as small as possible to make the curve in the display area
go through one or two periods so that it can get the higher range resolution.

If connect the under-the-test transmission line through the patch cord, user
needs to do the user calibration on the end of the patch cord. In this time, the cable
length compensation needs to be set as zero in FUNC menu.

What chart4-5 shows is the typical curve when testing the electric length. This
cable electric length is 1.432m. The actual length which is already known is 1.005m.
The velocity coefficient can be calculated as 0.7018.

Chart 4-5: Measuring the Cable Electric Length in Phase Frequency Characteristic

When the cable’s end is open circuit or short circuit, the cable loss is about half
of the return loss. When there is an antenna in cable connection, the echo loss in
antenna’s non-working frequency can be used for evaluating the cable loss
preliminarily.

4.4 Spectrum

We have enhanced the performance of KC901M’s input circuit. Therefore, it can
provide simple spectrum analysis display.

Warning:

KC901M’s input port’s maximal limit level is +20dBm. Limiting direct voltage is
15V. Once beyond them, the instrument will be broken immediately. When testing
the transmitter or the amplifier, a series of attenuators concatenated could assure
the input stays within the limitation at any time.

NOTice:

- 30 -

The determined maximum limiting power input level is for sake of keeping the
instrument safe only. It doesn’t guarantee the testing accuracy at this level. To obtain
more precise results, the input level should less than +13 dBm.

KC901M is an VNA, its spectrum function is only for reference use.

KC901M’s frequency spectrum mode can be interfered by the mirror image. So if
it is used for monitoring, concatenating a narrow-band filter on the input port is
suggested. When testing the short-wave frequency spectrum, concatenate a low-pass
filter (e.g. KC9504.02), which the cut-off frequency is 30MHz with suppression over
80dB at 110MHz, and then use it to filter the mirror image interference and IF
feed-though interference. User can also use different Local Mode to identify the
mirror image response. If there is IF feed-though interference, concatenate the
110MHz trap filter (KC9504.03).

There may occur a confusing peak of interference by another mirror which is
approximately 40dB lower than the main peak. It can be told from switching between
High LO and Low LO.
Better use the narrow-band antenna when the chosen frequency range is narrow. Set
CENT and SPAN according to the frequency range which needs to be tested. Also set
the AMP accordingly to the strength of the under-the-test signal. When searching the
weak signal, AMP should be set ≤-40dBm. Adopt smaller SPAN for more meticulous
sweep.

4.5 Detecting Interference Source

In the frequency band which has no image interference, user can detect the
interference source with KC901M by searching the maximum signal strength
direction.

After entering the frequency spectrum, set CENT to the frequency which may be
interfered and SPAN to a smaller value (1MHz for example). When the interference is
feeble, set AMP as -60dBm. Search the interference signal by adjusting antenna’s
directivity and its polarization mode till there appears a maximum bump in the central
of the spectrum. Use the magnetic compass to mark the azimuth angle of antenna’s
directivity and then draw a direction indication line on the map. Next, find another
place to do the test again and draws another direction indication line. The crossover
point of these two lines is the most probable location of the potential interference
source.

The line formed by the two testing points should cross with either one direction
line (mentioned above) at an angle between 60-120 °N, better close to 60 °N. (Chart
4-4)

The monitoring location should better be high and capacious enough to avoid
obstructive objects (such as buildings). Approaching the interference source, adjust
AMP according to the signal strength or use the field strength mode. Move towards

- 31 -

the strongest signal and gradually approach the interference source (the tested range
should be over 70dBμ (-37dBm) near the interference source).

Chart 4-4: Crossover Point and Operation Example on Map

Putting band pass filters between antenna and instrument can greatly improve
the testing reliability. Usually this filter is in helical structure or in cavity structure.
Before using it, user can adjust its pass-band frequency under KC901M’s monitoring.
When the testing signal is weak, user can also concatenate LNA (low noise amplifier)
between the filter and the instrument.

To locate an interference source exactly, besides the guiding theories and
auxiliary technologies, what you need are continuous practices to accumulate
necessary experiences and skills so as to enhance efficiency and effectiveness. After
several tests, especially the tests in cities and mountain areas, there will be various
illusory directions because of signal’s diffraction and the reflection.

* For the narrow-band signal, the interference source will have higher response
speed by being searched in field strength mode.

* When testing the emission field around radio station’s antennas, field strength
mode must be used. The medium frequency gain in the frequency spectrum mode
should be set by users themselves, but keep in mind that it may be broken by the
strong signal because of the wrong setting.

Warning:

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Unless permitted, DO NOT monitor the space frequency spectrum of the
non-working frequency with KC901M. Even if you accidentally do so, don’t reveal the
data to anyone.

Chapter Five : Maintenance

5.1 How to Clean the Screen, Keyboard and Ports

The glass pane of the display screen is replaceable. remove the protective film
from the screen, otherwise it will reduce the visibility under the sun.
Clean the display screen and the keyboard with a piece of wet tissue and dry up with
a gauze.

If there is dust inside, take the control circuit board apart, and clean it by
blowing it with 0.2MPa compressed air. If it’s necessary, change a new display screen
and the keyboard rubber.

Please clean the RF adaptors regularly. To start with, clean the inside of the ports
with dry cotton swabs. Then clean it with a cotton swab dipped with a bit of alcohol.
Core needle’s end face and the inside/outside steps of connector’s shell must be
cleaned very well. Core needle’s hole can be cleaned by spinning into it a slimly
twisted tissue.

Warning:

Before taking apart of the circuit board, all batteries and the charger must be
removed. Users can take apart of the instrument shell and the control circuit board
to install the batteries and clean the display screen, after which warranty is still
granted. But it will be out of the warranty range if there is any problem and damage
caused during taking it apart.

Wiping the instrument on any part with organic solvent is forbidden. Also be
careful not letting any fluid flow into the barometer.

5.2 Other Points for Attention

1. Please place the instrument into the suitcase or package during long-distance
transportation. Once taking out, tie it up to a strap to safe it from falling and crashing.
Do NOT put it together with something hard such as construction tools.

2. When testing some heavy devices, or connecting some thick and strong coax
cables, users should employ flexible cables to do the switch-over. Additionally, users
should perform calibration to erase the influence of the patch cord.

3. When installing the connector, insert it carefully into the right position. When
the core needle fits exactly into the core hole, screw the thread tight. Use one hand
to hold the instrument still and keep it from spinning, the other hand to rotate the
barrel. Also pay attention and check the connectors not frequently used. If the core
needle is too long or bent, repair it before connecting.

- 33 -

4. The instrument is NOT waterproof or moisture-proof. Thus as it gets wet, turn
off the power immediately and shake out the water from its bottom. Also disassemble
the instrument immediately and take out the batteries. Anyway if using the
instrument outdoors, better prepare a waterproof case.

5. In freezing winter, be aware of the sharp temperature difference that may
form dews in the inner part of the instrument.keep the instrument into a sealed
plastic bag right before taking it indoors from outdoors until the instrument suffers no
temperature difference. If there are dewdrops on the instrument, dry it before
starting.

6. In order to protect the batteries, charge the batteries regularly and not wait
till the power-shortage warning alerts. Also long-term floating charge is not permitted.
Take out the batteries before long-time charging.

7. Before setting aside the instrument for long time, make sure it remains 0.8V
voltage, and better remove the batteries. Also charge it at least once a year to 8.0V
despite it is idle.

8. Keep the instrument away from the high-power emission source, including the
ordinary walkie-talkie.

9. Ionization radiation may bring damages to the instrument; so will the neutron
exposure that could cause the irreversible damages to the instrument.

10. The USB plug is fragile. So use the flexible data cable and try to avoid the
lateral force.

11. Instrument’s retesting period is 1 year. It is advised to send it back to the
manufacturing factory to do the retest or calibration.

12. The warranty period is 1 year. Warranty does not include damages caused by
normal wear of the ports or the appearance, and any the artificial damage.

13. DO NOT take apart of instrument’s shell casually in that this is a precise
instrument, any damages caused by careless operation are beyond the warranty. Pay
attention that the instrument will not be eligible for warranty once the RF module
being disassembled.

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Chapter Six Technical Specification

6.1 Measurement Theory

KC901M’s circuit is comprised of one signal source and two receivers.
The signal source is divided into two frequency bands: the signal lower than 60MHz
(except audio frequency source) is produced by DDS directly; the one higher than
60MHz is produced by PLL. The signal sources of two frequency bands are gated by a
RF switch and converged into one RF signal to output.

Both receivers are digital-IF synchronous receivers. S21 function is so-called
“simplified vector” in that in this mode, the instrument’s receivers can only detect the
forward signal but not the reverse signal. So it can only run the simplified calibration
model. It only erases the errors of the frequency response.

Check Chart 6-1 for KC901M’s schematic diagram.

Chart 6-1: KC901M’s Schematic Diagram

KC901M’s signal source generates a RF CW signal and output at port 1 when
measuring S11 parameter. Use the Forward divider to get the forward signal and then
use a Directional Coupler after the divider to get the reverse signal. The forward
signal and the reverse signal are sent to two receivers respectively. After double

-conversion and ADC sampling, these two signal become a digital string and then are
sent to a FPGA for further processing. KC901M use the inner product of vector
method to measurement the phase and use the Rms detection to measurement the
amplitude. All the data of RF measurement are derived from calculating the
forward/reserve signal and the phase difference.

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When measuring S21 parameter the signal source will switch to the port 2, after

Table 1

Endurance Time

Function/Capacity

2200mAh

2600mAh

3100mAh

3400mAh

RF (S11)

3

4

5

5.5

Transmission/Insertion Loss

3

4

5

5.5

Spectrum/Field Strength

567

8

RF Signal Source

567

8

Audio Signal Source

6810

12

going through the DUT the signal input at port 1. The transition measurement is
based on the forward signal and the transition signal. KC901M cannot measure the
transition and reflection at the same time since the S21 measurement just supports a
simple calibration. Also the S21 measurement we call it “simple vector
measurement”.

In audio source signal function, DDS is used for outputting the audio signal
directly. KC901M uses the digital synthesizer which the clock frequency is 400MHz.
Therefore the audio signal source function can produce signal which the frequency is
over 50MHz. Also it supports FM, but the index is not guaranteed.

6.2 Charging Time and Endurance Time

The Rated charge current of KC901M’s batteries pack is 1A. The charging time
depends on the batteries capacity. Currently the existing battery with maximum
capacity in the market, has a single battery’s capacity that can reach 3.4Ah. If
installing four batteries, the charging time will be 4/2×3.4≈7h. When a single battery
has been charged to 4.2V and the voltage of battery pack is 8.4V, the instrument will
stop the charging automatically. When the temperature is too low or too high,
instrument will also slow down the charging speed.

KC901M’s endurance time is decided by the battery’s capacity and its applying
function. Turning on mode S11 and mode S21 simultaneously, together with one or
more than one receivers, consumes more power than using any other functions.
Functions like frequency spectrum, field strength, signal source are most
power-saving, since they only need to start up signal source and one of the receivers.
When in STOP state, the whole RF circuit will be turned off. In this time, only the
processor and other display part are consuming the power.

When installing four batteries, the display screen’s luminance is 20%. At the
same time, when the temperature is 15 ℃ , the endurance time of different
functions are shown in following table (Table 1). This table is only for reference. The
endurance time will be less when the temperature is too high/low or the battery’s
actual capacity is lower than stipulated.

- 36 -

Stop/Pause

121519

21

If there are only two batteries installed, the discharge rate becomes higher, so

Object

Test tate

Parameter

Note

Min

Type

Max

Freq. Range

Effective

9KHz

9.8GHz

SPEC can setting

0

9.8GHz

Sweep Range

SPAN

1KHz

9.8GHz

Sweep point

450pt

3150pt

Local
operation

Freq.
Resolution

All Sweep Function

1Hz

SPEC etc.

Single Point Function

0.1Hz

Generator
etc.

Level Resolution

0.01dB

Phase Resolution

0.01°

Sweep Speed

RBW=30KHz,each point

1.2ms

RBW=10KHz,each point

1.5ms

RBW=3KHz,each point

2ms

RBW=1KHz,each point

4ms

RBW=30K,450pt each
frame

0.5s

Output level
（sweep）

1MHz-7.5GHz

-13dBm

-3dBm

3dBm

port1

1MHz-7.55GHz

-3dBm

6dBm

10dBm

port2

7.5GHz-9.8GHz

-16dBm

0dBm

port1

7.5GHz-9.8GHz

-10dBm

10dBm

port2

Output level

1MHz-7.5GHz Generator

-6dBm

10dBm

12dBm

port2

Output
attenuator

RF Source(see note4)
0dB

25dB

port2

0dB

55dB

port1

Sensitive

1MHz-5GHz

-107dBm

port1
RBW=1KHz

5GHz-9.8GHz

-94dBm

Transmission
measurement
dynamic
range

1MHz-1.5GHz

80dB

Equivalent to
isolation
range

1.5GHz-4GHz

60dB

4GHz-9.5GHz

40dB

Transmission
measurement
uncertainty

After through
calibration and L ＜
60dB

0.5+0.05L

See note 2

Insertion
loss
zero drift

L＜30dB

0.05dB

Coupler
absolute

9kHz—1MHz

18dB

90% range
better

1MHz—9.8GHz

20dB

the endurance time will be half less than the time above.

6.3 Technical Parameter

- 37 -

directional

Coupler
relative
directional

50kHz—3GHz

45dB

After
calibration
， 90%range
better

3GHz—6GHz

35dB

6GHz—9.8GHz

30dB

Return Lose
Uncertain

After through
calibration，3dB＜ RL
＜25dB 时

1.5+0.1RL

Phase
Uncertain

9kHz—100kHz

8°

ρ＞0.25

100kHz—1GHz

2°

1GHz—3.55GHz

5°

3.55GHz—9.8GHz

10°

Port
VSWR

Port 2，1MHz-6GHz

1.5

Dynamic
Port 1，1MHz-6GHz

2.0

Lo leakage

Port 1

-60dBm

-10dBm

IF Feedthrough

<5.8GHz

10dB

>5.8GHz

30dB

First IF image attenuation

0dB

Second IF image attenuation

40dB

Spectrum absolute level Uncertainty

1.5dBm

3dBm

Frequence stability, year

0.3ppm

1ppm

Power Voltage

DC port

11V

32V

Temperature

Power adapter

105V

230V

battery

6.5V

8.4V

Operation

0℃

45℃

Humidity
Allow

-40℃

65℃

note3
95%

Broken Level

RF Port DC15V，
+20dBm。

Demesion

200×114×46mm（L×W×T）

Quality（Battery
included）

Instrument
Package

2.0kg

Note：Expect there are other specifications，the indexes are all tested through user calibration in
these following conditions:slow mode, RBW is 1KHZ,output attenuation is 0,temperature is 25℃.
Some minority and accidental parameters, or some permanent parameters may be out of the
technical parameter range.

[END]

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