1.4
Operational Procedure
After switching on the units, allow one minute before the taking of readings on the detector,
as the internal circuitry must be allowed to stabilise before correct results will be indicated.
When testing any type of equipment, always check for system operation by operating the
phase reverse switch on the source. A corresponding reversal will be indicated by the
phase LED's on the detector. This will serve as a check that the system is functioning
correctly.
1.5
Signal Levels
Always ensure the source's output level is sensible for the equipment under test, and does
not cause overloading. Excessive hum or noise may cause indeterminate results, with
detector LED's alternately lighting.
1.6
Source Frequency
This must be set appropriately for the equipment under test, especially where it may have
frequency dependant parts and contain major phase shifts. Refer to the following sections
for specific details. When supplied, the frequency ranges will have been set to LOW =
110hz;
M1 = 500Hz; M2 = 3k5Hz; H = 10kHz.
2.0
APPLICATIONS
2.1
Passive Components
This includes connecting cables, transformers, line attenuators, etc. Connect the source to
the input, and the detector to the output, observing all the points as in section one above.
The source output level switch can be at OdB, and the tone frequency set to band Ration
M1. High ratio transformers should be tested in a step-down mode.
2.2
General Equipment
This includes all forms of signal processing units. Those containing filters or other
frequency/phase changing parts, should have their cancel or bypass switches operated.
Connect the source to the input, and the detector to the output, observing all points as in
section one above. The source output level should be set to suit the particular unit, to avoid
any overload within it. The detector has a wide dynamic range for its input level and will
accept anything from a few millivolts, up to fifty volts. For all wide-band equipment, the
source tone frequency can be set to either range M1 or M2.
2.3
Microphones
For phantom powered types, a separate powering unit will be required. For high impedance
moving coil types, a step-down transformer will be required. Connect the source to a
loudspeaker, either directly or via a power amplifier, and adjust to give a comfortable
listening level. The tone frequency can be set to either range M1 or M2. Connect a
microphone with a known phase wiring to the detector, and hold up to the loudspeaker, on
axis, and observe the phase LED colour. Repeat with the unknown microphone, and
compare phase LED colour with that of the known reference. For some microphones it
might be necessary to adjust the tone frequency to avoid a particular peak or dip in the
phase response.
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Summary of Contents for AR 130
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