AA-230 ZOOM
Antenna and cable analyzer
RigExpert
®
User’s manual
.
Introduction
Operating the AA-230 ZOOM
First time use
Main menu
Multifunctional keys
Connecting to your antenna
SWR chart
Chart ZOOM
Data screen
Frequency and range entry
Return loss chart
R,X chart
Smith chart
Memory operation
SWR mode
Display all parameters
MultiSWR mode
Applications
Antennas
Coaxial lines
Measurement of other elements
Annexes
Annex 1: Specifications
Annex 2: Precautions
Annex 3: Tools menu
Annex 4: Setup menu
Annex 5: TDR mode
Annex 6: Calibration
Table of contents
25
26
29
21
24
24
30
34
13
13
14
10
11
12
9
9
10
8
8
8
5
6
6
7
7
4
5
5
Introduction
1
Thank you for purchasing a
RigExpert
AA-230 ZOOM
Antenna and Cable Analyzer!
We did our best to make it powerful yet easy to use.
The analyzer is designed for measuring SWR
(standing wave ratio), return loss, cable loss, as well as other parameters of cable and antenna systems in the range of 100 kHz to
230 MHz. A built-in ZOOM capability makes graphical measurements especially effective.
An integrated Time Domain Reflectometer mode can be used to locate a fault within the feedline system.
2
3
The following tasks are easily accomplished by using this analyzer:
• Rapid check-out of an antenna
• Tuning an antenna to resonance
• Comparing characteristics of an antenna before and after specific event (rain, hurricane, etc.)
• Making coaxial stubs or measuring their parameters
• Cable testing and fault location, measuring cable loss and characteristic impedance
• Measuring capacitance or inductance of reactive loads
4
1.
Antenna connector
2.
Liquid crystal display
3.
Keypad
4.
USB connector
4
User’s manual
First time use
Operating the
AA-230 ZOOM
Please insert four AAA batteries
(either alkaline or Ni-MH ones) into the battery compartment of the analyzer, watching the polarity. Instead, you may power it from a spare USB port of your computer by using a conventional USB cable.
Press the (Power) key located at the bottom-right corner of the keypad to turn on the analyzer. After displaying the initial message (showing a firmware version and a serial number of the instrument), a
Main menu
appears on the screen.
The analyzer will be turned off automatically if not in use for too long.
Main menu
The Main menu acts as a starting point from where different tasks may be launched.
Use (Cursor up) and (Cursor down) keys to scroll through the menu, then press (OK) to select an item.
For your convenience, a battery indicator is shown at the top-left corner of the screen. This indicator is replaced with a USB icon when the analyzer is connected to your computer.
You may use hot keys for the quick access to certain tasks. For instance, press the (SWR chart) button to open the SWR chart screen immediately.
RigExpert AA-230 ZOOM
5
Multifunctional keys
Most keys on the analyzer’s keypad perform several functions.
For instance, numbers (1) are used to enter frequency and other numerical parameters.
Main functions (2) provide quick access to most common tasks. Alternative functions (3) are executed if the user holds the (Functional) key. For the convenience, alternative functions are marked with yellow.
3
2
1
You may press the (Help) key to open a help screen listing all active hot keys.
Connecting to your antenna
Plug the cable to your analyzer’s antenna connector, and then tighten the rotating sleeve. The rest of the connector, as well as the cable, should remain stationary.
If you twist other parts of the connector when tightening or loosening, damage may easily occur. Twisting is not allowed by design of the N-connector.
6
User’s manual
SWR chart
Once your antenna is connected to the analyzer, it is time to measure its characteristics. Press the (SWR chart) key to open the SWR chart screen, then press (OK) to start a new measurement.
A few moments later, the result will be displayed on the analyzer’s screen.
Press the + key combination to run a continuous sweep.
A small triangle at the bottom of the chart corresponds to a point at which the SWR reaches its minimum.
Chart ZOOM
Use the arrow keys to increase or decrease the center frequency or the scanning range.
Watch the chart zooming in or out, or changing its position. Use the (Functional key) and (Cursor up) or (Cursor down) key combination to zoom the vertical scale of the chart.
Do not forget to press the (OK) key for the new measurement to start.
RigExpert AA-230 ZOOM
7
Data screen
The data screen is available in all chart modes. Press the
(Data) key to display various parameters of a load at cursor.
Frequency and range entry
To enter the center frequency or the sweep range, press the (
Frequency,
Range
) key.
Use cursor keys to navigate, or the to keys to enter values. Do not forget to press the (OK) key to apply.
Press (Up) or (Down) cursor keys while holding the (Functional) key to quickly choose a radio amateur band.
Return loss chart
The return loss (
RL
) chart, which is very similar to the
SWR chart
, is activated by pressing the (Functional key) and (RL chart) key combination in the
Main menu
.
8
User’s manual
R,X chart
Press the
(R,X chart) key in the
Main menu
to access the
R,X chart
mode.
Positive values of reactance (X) correspond to inductive load, while negative values correspond to capacitive load.
The chart will display
R
and
X
for series or parallel models of a load. Press
(Functional key) and to switch between these models.
The marker at the bottom of the screen shows a resonant frequency closest to the center of the scan.
Smith chart
The (Smith chart) key opens a screen where the reflection coefficient is plotted on the
Smith chart
.
For a list of hot keys, press the
(Help) key, as usual.
A small marker is used to indicate the center frequency.
RigExpert AA-230 ZOOM
9
Memory operation
Press the (Save) key to save the chart into one of 100 available memory slots.
To retrieve your readings from the memory, press then (Load) key, select a memory slot number and press
(OK).
To rename any existing memory slot, press (Functional key) and (Edit) key combination.
SWR mode
To watch the SWR at a single frequency, press the (SWR) key.
Do not forget to press the (OK) key to start or stop the measurement.
Change the frequency with (Left) or (Right) cursor keys, or press the (Frequency) key to enter a new frequency.
10
The SWR icon in the top-left corner flashes when the measurement is performed.
User’s manual
Display all parameters
To display various parameters of a load on a single screen, press the key.
(All)
Do not be confused by negative values of L or C. This can be useful for experienced users.
This screen displays values for series as well as parallel models of impedance of a load.
• In the series model, impedance is expressed as resistance and reactance connected in series:
• In the parallel model, impedance is expressed as resistance and reactance connected in parallel:
Z = R + jX
R
X
Z = R ||+ jX
R X
RigExpert AA-230 ZOOM
11
MultiSWR mode
Press the (Functional key) and
(Multi) key combination to see the SWR at up to five different frequencies. This mode may be useful for tuning multiband antennas.
Use (Up) and (Down) cursor keys to select a frequency to be set or changed, then press the (Frequency) key to enter a new value. Do not forget to press the
(OK) key to start the measurement.
12
User’s manual
RigExpert AA-230 ZOOM
Applications
Antennas
Checking the antenna
It is a good idea to check an antenna before connecting it to the receiving or transmitting equipment. The
SWR chart
mode is good for this purpose.
The picture on the left shows the
SWR chart of a car VHF antenna. The operating frequency is 145.5 MHz. The
SWR at this frequency is about 1.25, which is acceptable.
The next screen shot shows SWR chart of another car antenna. The actual resonant frequency is about 146.7 MHz, which is too far from the desired one.
The SWR at 145.5 MHz is 2.7, which is not acceptable in most cases.
13
Adjusting the antenna
When the measurement diagnoses that the antenna is off the desired frequency, the analyzer can help in adjusting it. Physical dimensions of a simple antenna (such as a dipole) can be adjusted knowing the actual resonant frequency and the desired one.
Other types of antennas may contain more than one element to adjust (including coils, filters, etc.), so this method will not work. Instead, you may use the
SWR mode
, the
All parameters mode
or the
Smith chart mode
to continuously see the results while adjusting various parameters of the antenna.
For multi-band antennas, use the
MultiSWR mode
. You can easily see how changing one of the adjustment elements (trimming capacitor, coil, or physical length of an aerial) affects SWR at up to five different frequencies.
Coaxial lines
Open- and short-circuited cables
The pictures on the right show
R and
X charts
for a piece of cable with open- and short-circuited far end. A resonant frequency is a point at which X
(reactance) equals to zero:
• In the open-circuited case, resonant frequencies correspond to (left to right) 1/4, 3/4, 5/4, etc. of the wavelength in this cable;
• For the short-circuited cable, these points are located at 1/2, 1, 3/2, etc. of the wavelength.
14
User’s manual
Cable length measurement
Resonant frequencies of a cable depend on its length as well as on the velocity factor.
A velocity factor is a parameter which characterizes the slowdown of the speed of the wave in the cable compared to vacuum. The speed of wave (or light) in vacuum is known as the electromagnetic constant: c=
299,792,458 meters
(or
983,571,056 feet
) per second.
Each type of cable has different velocity factor: for instance, for RG-58 it is 0.66.
Notice that this parameter may vary depending on the manufacturing process and materials the cable is made of.
To measure the physical length of a cable,
1. Locate a resonant frequency by using the
R,X chart
.
Example:
The 1/4-wave resonant frequency of a piece of open-circuited RG-58 cable is
4100 kHz.
2. Knowing the electromagnetic constant and the velocity factor of the particular type of cable, find the speed of electromagnetic wave in this cable.
299,792,458
×
0.66 =
197,863,022 meters per second
- or -
983,571,056
×
0.66 =
649,156,897 feet per second
RigExpert AA-230 ZOOM
15
3. Calculate the physical length of the cable by dividing the above speed by the resonant frequency (in Hz) and multiplying the result by the number which corresponds to the location of this resonant frequency (1/4, 1/2, 3/4, 1, 5/4, etc.)
197,863,022 / 4,100,000
×
(1/4) =
12.06 meters
- or -
649,156,897 / 4,100,000
×
(1/4) =
39.58 feet
Velocity factor measurement
For a known resonant frequency and physical length of a cable, the actual value of the velocity factor can be easily measured:
1. Locate a resonant frequency as described above.
Example:
5 meters (16.4 feet) of open-circuited cable. Resonant frequency is 9400 kHz at the 1/4-wave point.
2. Calculate the speed of electromagnetic wave in this cable. Divide the length by 1/4, 1/2, 3/4, etc. (depending on the location of the resonant frequency), then multiply by the resonant frequency (in
Hz).
5 / (1/4) × 9,400,000 =
188,000,000 meters per second
- or -
16.4 / (1/4) × 9,400,000 =
616,640,000 feet per second
3. Finally, find the velocity factor.
Just divide the above speed by the electromagnetic constant.
188,000,000 / 299,792,458 = 0.63
- or -
616,640,000 / 983,571,056 = 0.63
16
User’s manual
Cable fault location
To locate the position of a probable fault in a cable, just use the same method as when measuring its length. Watch the behavior of the reactive component (
X
) near the zero frequency:
• If the value of X is moving from –
∞
to 0, the cable is open-circuited:
• If the value of X is moving from 0 to +
∞
, the cable is short-circuited:
RigExpert AA-230 ZOOM
17
Making 1/4-
λ
, 1/2-
λ and other coaxial stubs
Pieces of cable of certain electrical length are often used as components of baluns (balancing units), transmission line transformers or delay lines. To make a stub of the predetermined electrical length,
1. Calculate the physical length. Divide the electromagnetic constant by the required frequency (in Hz). Multiply the result by the velocity factor of the cable, then multiply by the desired ratio (in respect to
λ
).
2. Cut a piece of cable slightly longer than this value. Connect it to the analyzer. The cable must be open-circuited at the far end for 1/4-
λ
, 3/4-
λ
, etc. stubs, and short-circuited for 1/2λ , λ , 3/2λ , etc. ones.
3. Switch the analyzer to the
All parameters
measurement mode. Set the frequency the stub is designed for.
4. Cut little pieces (1/10 to 1/5 of the margin) from the far end of the cable until the
X
value falls to zero (or changes its sign). Do not forget to restore the open-circuit, if needed.
Example:
1/4λ stub for 28.2 MHz, cable is RG-
58 (velocity factor is 0.66)
299,792,458 / 28,200,000 × 0.66 ×
(1/4) = 1.75 meters
- or -
983,571,056 / 28,200,000 × 0.66 ×
(1/4) = 5.75 feet
A piece of 1.85 m (6.07 ft) was cut.
The margin is 10 cm (0.33 ft). The cable is open-circuited at the far end.
28,200 kHz was set.
11 cm (0.36 ft) were cut off.
18
User’s manual
Measuring the characteristic impedance
The characteristic impedance is one of the main parameters of any coaxial cable.
Usually, its value is printed on the cable by the manufacturer. However, in certain cases the exact value of the characteristic impedance is unknown or is in question.
To measure the characteristic impedance of a cable,
1. Connect a non-inductive resistor to the far end of the cable. The exact value of this resistor is not important.
However, it is recommended to use 50 to
100 Ohm resistors.
2. Enter the
R,X chart
mode and make measurement in a reasonably large frequency range (for instance, 0 to 200
MHz).
Example 1: 50-Ohm cable with 75 Ohm resistor at the far end.
Example 2: Unknown cable with 50
Ohm resistor at the far end.
Example 1:
50-Ohm cable
RigExpert AA-230 ZOOM
Example 2:
Unknown cable
19
3. Changing the display range and performing additional scans, find a frequency where
R
(resistance) reaches its maximum, and another frequency with minimum. At these points,
X
(reactance) will cross the zero line.
4. Switch to the
Data at cursor
screen by pressing the
(Data) key and find values of
R
at previously found frequencies.
Example 1:
30.00 MHz – min., 60.00 MHz – max.
Example 2:
41.00 MHz – max., 88.40 MHz – min.
Example 1:
33.0 Ohm – min., 78.5 Ohm – max.
Example 2:
99.2 Ohm – max, 53.4 Ohm – min.
5. Calculate the square root of the product of these two values.
Example 1: square root of (33.0
×
78.5) =
50.7 Ohm
Example 2: square root of (99.2 × 53.4) =
72.8 Ohm
20
User’s manual
Measurement of other elements
Although RigExpert AA-230 ZOOM is designed for use with antennas and antennafeeder paths, it may be successfully used to measure parameters of other RF elements.
Capacitors and inductors
The analyzer can measure capacitance from a few pF to about 0.1 μF as well as inductance from a few nH to about 100 μH. Since measuring of capacitance and inductance is not a main purpose of RigExpert analyzers, the user will have to gain some experience in such measurements.
Be sure to place the capacitor or the inductor as close as possible to the RF connector of the analyzer.
1. Enter the
R,X chart
mode and select a reasonably large scanning range. Perform a scan.
Example 1:
Unknown capacitor
RigExpert AA-230 ZOOM
Example 2:
Unknown inductor
21
2. By using left and right arrow keys, scroll to the frequency where X is -25…-100 Ohm for capacitors or 25…100 Ohm for inductors. Change the scanning range and perform additional scans, if needed.
3. Switch to the
Data at cursor
screen by pressing the capacitance or inductance.
key and read the value of
Example 1:
Unknown capacitor
Example 2:
Unknown inductor
Transformers
RigExpert analyzers can also be used for checking RF transformers. Connect a 50 Ohm resistor to the secondary coil (for 1:1 transformers) and use
SWR chart
,
R,X chart
or
Smith chart
modes to check the frequency response of the transformer. Similarly, use resistors with other values for non-1:1 transformers.
22
User’s manual
Traps
A trap is usually a resonant L-C network used in multi-band antennas. By using a simple one-turn wire coil, a resonant frequency of a trap may be measured.
Example:
A coaxial trap constructed of 5 turns of TV cable (coil diameter is 6 cm) was measured.
A one-turn coil (about 10 cm in diameter) connected to the analyzer was placed, co-axially, a few centimeters away from the measured trap. The SWR chart shows a visible dip near 17.4 MHz, which is a resonant frequency of the trap.
RigExpert AA-230 ZOOM
23
Annex 1
Specifications
Frequency range:
0.1 to 230 MHz
Frequency entry:
1 kHz resolution
Measurement for
25, 50, 75 and
100-Ohm systems
SWR measurement range:
• 1 to 100 in numerical modes
• 1 to 10 in chart modes
SWR display:
numerical or analog indicator
R and X range:
• 0…10000, -10000…10000 Ohm in numerical modes
• 0…1000, -1000…1000 Ohm in chart modes
Display modes:
• SWR at single or multiple frequencies
• SWR, return loss, R, X, Z, L, C at single frequency
• SWR chart, 100 to 500 points
• R, X chart, 100 to 500 points
• Smith chart, 100 to 500 points
• Return loss chart, 100 to 500 points
• TDR chart (Time Domain
Reflectometer)
• Cable tools (loss and characteristic impedance)
Optional open-short-load calibration.
RF output:
• Connector type: N
• Output signal shape: square
• Output power: -10 dBm (at 50 Ohm load)
Power:
• Four 1.5V alkaline batteries, type AAA
• Four 1.2V Ni-MH batteries, type AAA
• Max. 4 hours of continuous measurement, max. 2 days in standby mode when fully charged batteries are used
• When the analyzer is connected to a
PC or a DC adapter with USB socket, it takes power from these sources
Interface:
• 290
×
220 color TFT display
• 6x3 keys on the water-proof keypad
• Multilingual menus and help screens
• USB connection to a personal computer
Dimensions:
82
×
182
×
32 mm
(3.2 × 7.2 × 1.3 in)
Operating temperature:
0…40 °C
(32…104 °F)
Weight:
236 g (8.32 oz)
Warranty:
2 years
RigExpert AA-230 ZOOM is made in Ukraine.
24
User’s manual
Annex 2
Precautions
Never
connect the analyzer to your antenna in thunderstorms.
Lightning strikes as well as static discharge may kill the operator.
Never
leave the analyzer connected to your antenna after you finished operating it. Occasional lightning strikes or nearby transmitters may permanently damage it.
Never
inject RF signal or DC voltage into the antenna connector of the analyzer. Do not connect it to your antenna if you have active transmitters nearby.
Avoid
static discharge while connecting a cable to the analyzer. It is recommended to ground the cable before connecting it.
Do not
leave the analyzer in active measurement mode when you are not actually using it. This may cause interference to nearby receivers.
If using a personal computer,
first
connect the cable to the antenna connector of the analyzer,
then
plug the analyzer to the computer
USB port. This will protect the analyzer from static discharges.
RigExpert AA-230 ZOOM
25
Annex 3
Tools menu
For the quick access to the the Tools menu, press the
Cable loss
To measure the loss in a coaxial cable, connect a piece of a cable to the antenna connector of the analyzer. Make sure the far end of the cable is open circuited.
Press
(OK) to start.
Next, short circuit the far end of the cable and press
(OK) to continue.
Once the analyzer finishes the measurement, you will see the
Loss versus frequency chart
. Use and
(Left)
(Right) cursor keys to change frequency and watch the loss value in decibels at the bottom of the analyzer’s screen.
+
key combination.
To see the list of other keypad shortcuts, press the (Help) key.
26
User’s manual
RigExpert AA-230 ZOOM
Cable impedance
To measure the characteristic impedance, use a piece of an open circuited cable: a half of a meter (or a foot) or longer should be fine. Press
(OK) to start.
Next, the far end of the cable should be short circuited. Press
(OK) to continue.
There are several reasons why the resulting chart does not look smooth, so we need to use (Left) and
(Right) cursor keys to find the location where the impedance is stable. The result is shown at the bottom left corner of the screen.
Use
+
(Up) and
+
(Down) key combinations to change the scale, if needed.
27
Self tests
There are several built-in self tests in the
AA-230 ZOOM analyzer, which can be run by the user to make sure the analyzer is working properly.
Make sure all cables or adapters are disconnected from the antenna connector of your analyzer, then press
test
).
(OK) to start the first test (
Detector
You should see the “
Passed
” message in case of success.
Continue with two more tests: the second
(
Built-in filter test
) and the third (
Test with load
). For the third test, make sure to connect a good 50 Ohm load directly to the analyzer’s antenna connector.
28
User’s manual
RigExpert AA-230 ZOOM
Annex 4
Setup menu
For the quick access to the
Setup
menu, press the
+
key combination.
There are several settings in the
Setup
menu:
• Language
– select a language for the analyzer’s menus
• Palette
– choose a color scheme
• Battery
– select a power consumption scheme
• Sound
– select sound volume
• Sys. imp.
– select system impedance
(25, 50, 75 or 100 Ohm) which affects
SWR and return loss readings.
• Units
– select metric (meters) or imperial (feet) units
• Bands
– select region for highlighting of radio amateur bands
• Cable vel. factor
– choose a velocity factor of the coaxial cable for the TDR mode
• Freq. corr.
– frequency correction of the analyzer’s oscillator
• Data points
– select a number of data points for each frequency sweep
• Reset settings
– reset the analyzer to factory defaults
• Clear saved charts
– clear all memory slots
29
Annex 5
TDR mode
Theory
Time domain reflectometers (
TDR
) are electronic instruments used for locating faults in transmission lines.
A short electrical pulse is sent over the line, and then a reflected pulse is observed. By knowing the delay between two pulses, the speed of light and the cable velocity factor, the DTF (distanceto-fault) is calculated. The amplitude and the shape of the reflected pulse give the operator idea about the nature of the fault.
Instead of a short pulse, a “ step” function may be sent over the cable.
30
User’s manual
Unlike many other commercially-available reflectometers, RigExpert AA-230 ZOOM does not send pulses into the cable. Instead, another technique is used. First,
R
and
X
(the real and the imaginary part of the impedance) are measured over the whole frequency range (up to 230 MHz). Then, the IFFT (Inverse Fast Fourier Transform) is applied to the data. As a result, impulse response and step response are calculated.
This method is often called a “
Frequency Domain Reflectometry”, but the “TDR” term is used in this document since all calculations are made internally and the user can only see the final result.
The vertical axis of the resulting chart displays the reflection coefficient: Γ =-1 for short load, 0 for matched impedance load (ZLoad=Z0), or +1 for open load. By knowing the cable velocity factor, the horizontal axis is shown in the units of length.
Single or multiple discontinuities can be displayed on these charts. While the Impulse
Response chart is suitable for measuring distance, the Step Response chart helps in finding the cause of a fault.
See the examples of typical
Step Response
charts on the next page.
RigExpert AA-230 ZOOM
31
32
User’s manual
Practice
Press charts:
+
(TDR) to open Impulse Response (
IR
) and Step Response (
SR
)
The velocity factor of the cable, as well as display units (meters or feet) may be changed in the
Settings menu
. You may disconnect your antenna or leave it connected to the far end of the cable. This will only affect the part of the chart located behind the far end of the cable.
The (OK) key starts a new measurement, which will take some time. Use the arrow keys to move the cursor or to change the display range. Watch the navigation bar at the top-right corner of the screen to see the current position of the displayed part of the chart.
The
(Save) key will start a new measurement, saving results in one of 100 memory slots. The
key will retrieve saved data. Use the + combination to edit memory names, if needed. Pressing
(Data) opens a data screen which displays numerical values of impulse and step response coefficients, as well as Z (estimated impedance) at cursor. The key will display the help screen, as usual.
RigExpert AA-230 ZOOM
33
Annex 6
Calibration
Although RigExpert AA-230 ZOOM is designed for high performance without any calibration, an open-short-load calibration may be applied for better precision.
The standards used for calibration should be of high quality. This requirement is especially important for high frequencies (100 MHz and upper). Three different calibration standards should be used: an “
open
”, a “
short
” and a “
load
” (usually, a
50-Ohm resistor). A place where these standards are connected during calibration is called a reference plane. If the calibration is done at the far end of a transmission line, parameters of this line will be subtracted from measurement results and the analyzer will display “true” parameters of a load.
34
User’s manual
RigExpert AA-230 ZOOM
To perform an open-short-load calibration, select
Calibrate
in the
Main menu
(or just press the combination).
+ key
Following the instructions on the screen, connect “
open
“, “
short
“ and “
load
“ calibration standards to the antenna connector of the analyzer.
You may connect calibration standards to the far end of a cable, so the cable will be “nulled”.
To apply calibration, press the
+ key combination in any measurement mode. The “
CAL
“ mark will appear at the bottom left corner of the screen.
35
http://www.rigexpert.com
Copyright © 2015 Rig Expert Ukraine Ltd.
“RigExpert” is a registered trademark of Rig Expert Ukraine Ltd.
Made in Ukraine
Doc. date: 12-Oct-2015
