3M 900AST User Manual

Advanced Systems
Tester

900AST Series

Coaxial Wire Testing

Technical Tip

December 2005
78-8135-6156-6-A

3M™ Advanced Systems Tester 900AST Series

Setup for Use

Battery Requirement

The battery holder holds six “AA” standard alkaline
batteries and should be installed prior to using the
unit. Please see the 900AST tester manual or DVD
for battery installation instructions. Always initiate a
self-calibration after installing new batteries.

The battery symbol in the upper right-hand corner
of the display gives an indication of the approximate
battery capacity. Each bar represents one-quarter of
the full capacity.

Front Panel

Test Leads

The test lead icons are shown on each of the
measurement screens and appear after a function or
test is selected. Each lead points to a color dot on
the front label that corresponds to the actual test lead
and test jack to be used. This on screen display is the
connection diagram for the selected test. The active
control keys are displayed on the bottom of the
screen and act as a guide through setup and testing.

For TDR applications using the special coaxial TDR
test lead(s), the test lead icons indicate which test
jacks (also denoted by colors) to use.

Operational Help

For operational information, refer to the 900AST
tester manual or “Help”
900AST tester keypad. For technical service,
warranty or repair questions, call 800 426 8688 (US
and Canada) or contact your local 3M representative.

control key on the

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3M™ Advanced Systems Tester 900AST Series

Keypad

The 900AST tester keypad has twelve yellow and
red “Control Keys” and nine blue “Function Keys”.
Additional blue keys on the keypad are reserved for
future expansion and have no designation or current
function.

Control Keys

Use the red and yellow keys to control and setup the
900AST tester and its functions.

Use the [Return] key to return to a previous
step in a function.

Use the [Contrast] key to adjust the contrast
or to turn the backlight on or off.

Use the [Save] key for storing TDR traces.

Use the [On/Off] key to turn the 900AST
power on or off (also see “Power Down
Timeout”).

Use the [Tab] key to select between
different options.

Use the [Setup] key to change the setup of a
function.

Use the [Help] key to get context sensitive
help with any screen or function.

Use the [Enter] key to accept changes or
move to the next step in a function. To
insert a space to the left of the cursor press
enter.

Use the [Up] and [Down] keys to
scroll to different menu options
or insert/delete characters when
editing.

Use the [Left] and [Right] keys to
select different options or move the
TDR cursor

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3M™ Advanced Systems Tester 900AST Series

Contrast and Backlighting

Note: Use of backlight decreases available battery

capacity.

Press the

Use the
the key again to turn the backlight on or off.

Use the

key to display the contrast screen.

and

keys to adjust the contrast. Press

key to return to previous screen.

Function Keys

Use the blue keys to select the different tests in the
900AST tester. The blue keys become number or
letter keys when editing.

Use the [Voltage] key to measure DC or AC
voltage.

Use the [Load] key to measure the current
through a simulated load lamp.

Use the [Resistance] key to measure
resistance and access the ‘Soak Test’ and
‘Contact Resistance’ functions.

Use the [Toolbox] key to access: Self
Calibration, Stored Results, Special
Resistance, and the Ohms to Distance
Calculator

Use the [Capacitance] key to measure the
capacitance of a component or circuit.

Use the [Tone] key to send interrupted tone
for circuit identification.

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3M™ Advanced Systems Tester 900AST Series

Use the [RFL] key to find the distance to a
resistance fault between two conductors or a
conductor and ground.

This key is used for editing only.

Use the [TDR] key to activate the Time
Domain Reflectometer.

Use the [Auto] key to activate automatic
TDR trace analysis.

 CAUTION

The 900AST tester is a tool for troubleshooting wiring

problems. It is not designed for troubleshooting electronic
circuits or instrumentation. The ohms, soak, contact
resistance, special resistance and RFL functions
generate a current limited (< 1 mA) 80V stimulus.
TDR and Auto TDR functions generate high-energy
electromagnetic pulses. Unexpected measurement
results and/or damage are possible if applied to
electronic circuits.

Circuit testing should be performed by personnel trained

in electrical safety practices and in accordance with
applicable safety standards.

Connecting to Coaxial Wires for Testing

Ensure that electrical power has been removed and
components disconnected from the wiring to be
tested before beginning wiring tests.

Note: For best operation, use the special coaxial

TDR test leads supplied with your 900AST
tester to perform coaxial wire TDR
measurements.

The TDR test cable has a standard male BNC
connector on the end. Plug the opposite end of the
TDR test leads plug into the Red/Black and/or Blue/
Yellow test jacks on the 900AST tester (one or more
cables may be used depending on the desired TDR
mode.)

Connect the end of the TDR test cable to the coaxial
wire to be tested. Use a BNC adapter (if needed) to
connect to the coaxial circuit under test.

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3M™ Advanced Systems Tester 900AST Series

TDR Setup

The TDR features a setup function that allows you to
select the type of Coaxial wire to be tested.

From the TDR Menu, press the Setup key to
enter the TDR Setup.

Press the select key and the and arrow
keys to highlight coaxial cable for wire type.

Use the
box. Use the

select key to move to the wire gauge

and keys to highlight the type
of coaxial cable to be tested and select ‘minimum
possible’ or ‘last used’ initial measurement length
setting.

Note: The 900AST tester maintains modified Vp

settings in internal memory. Press the
key in the TDR Setup screen to restore
original default Vp settings for all wire types.

Use the blue numeric keys changes the velocity
factor for the selected coaxial wire type or use the
default setting.

Press the enter key

to accept changes and

proceed.

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