Redback Q 2003 Operating Manual

FEATURES:
• 16 x 2 LCD shows impedance, 100V and 70V load value.
• 1Ω to 19KΩ test range
• Single push button operation.
• Auto ranging.
• Inbuilt Battery charger circuit.
• Display accuracy +/-10%.
• Low battery indication.
• Backlit display.
• Rugged yet easy to hold hand held case.
• Easy battery replacement.
• System test mode.
INTRODUCTION:
Measuring a transformer with a regular ohm meter or
multimeter is very difficult and provides inaccurate results.
This is because an ohm meter or multimeter uses DC to
measure the resistance.
Consider a transformer, which is basically a coil of wire, the
DC resistance will be fairly low. If an AC signal is passed
through the winding the impedance will be much higher,
unless the winding is shorted. In this case the reading will
be very low.
In the case of a short circuit the inductance of the transformer
tries to impede the current flow through the winding. The
nature of transformers will result in the impedance being
reflected into other windings on the transformer being
tested. This means a shorted turn on any winding will show
up on the other windings.
An impedance meter is also critical for accurately measuring
low impedance loudspeaker systems, incorporating multiple
speakers and crossovers, and for measuring commercial 100V
line speaker systems, which may include many speakers with
line transformers and several hundred meters of cable. Trying

Operating Manual

Q 2003
to measure this type of load is virtually impossible with a
standard multimeter.
For example a short circuit on several hundred metres of cable
will not show up as a short circuit on a standard multimeter.
You will actually measure the DC resistance of the cable
which will be around 22 ohms for 500 meters of 24/0.2
cable.
Using an impedance meter, measuring the AC resistance will
read a short circuit. A short circuit located remotely in a
speaker line is the major cause for amplifiers overheating
and blowing DC fuses.
Shorted turns on mains transformers primary windings can
also be measured with this meter. If this meter displays
a value of less than 100 ohms, this will indicate that the
transformer has a shorted turn.
OPERATION:
TO MEASURE IMPEDANCE
Make sure the amplifier has been completely disconnected
from the line to be measured.
Connect the test leads to the Q 2003.
Connect the test leads to the speaker line.
Once your meter is connected press the TEST button for
approximately 1 second (or 2 seconds if the LCD backlight
is required). The impedance meter will display "CHECKING
LOAD" for approximately 3 seconds while it checks the
speaker load. You will be able to hear a tone from the speaker
load that is under test. After 3 seconds the load impedance
will be displayed on the LCD along with the 100V load value.
After 8 seconds the 70V load value will replace the 100V
load value on the LCD.
User manual revision number 1.0 04/01/2017
www.altronics.com.au
Impedance Meter