User manual

User Manual PS 260 / Issue 1 © 1994 ASL Intercom, Utrecht, Holland.
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8.0 PARTY LINE, TECHNICAL CONCEPT 10.0 TECHNICAL SPECIFICATIONS PS 260
ASL's PRO Series offers a complete two way ('full duplex')
communications system. input impedance min. 10Kohm
Users of the system are connected via a 'party line'. input level +30 to - 10 dBm
Master stations (with built-in power supply), beltpacks, frequency response 60Hz - 20KHz (-3dB)
speaker stations and power supplies are interconnected
via standard microphone cable. One wire is used as an
audio line, one as a power line and the screen of the cable Max. output current 3mA rms
functions as earth/return. output impedance > 150 Kohm
Current drive is used for signal transfer. Each station
utilises a current amplifier to amplify the microphone signal output impedance < 25 ohms
and place it on the common audio line where, due to the maximum load 600 ohms
constant line impedance (situated in the power supply max. output level +20 to -20 dBm
between XLR pin 3 and 1), a signal voltage is developed frequency response 40 Hz - 20 Khz
which can be further amplified and sent to headphones or
loudspeakers.
This principle has three advantages:
- the use of a single audio line allows several stations to
talk and listen simultaneously. width 19" (483mm)
- due to the high bridging impedance offered by each height 1U (44.5mm)
station, the number of stations 'on line' has no depth 126mm
influence on the level of the communications signal. weight 1565 grams
- power and audio to the intercom stations use the same
cable.
The Call signal is also sent as a current on the audio line. supply voltage +30VDC (12V to 32V)
It develops a DC potential over the line impedance which supply current 33 mA quiescent / each
will be sensed by each station and interpreted as a Call audio line level -18dBm (max. 0dBm)
signal. signal-to-noise 80dB
9.0 GUARANTEE
This unit is warranted by ASL Intercom to the original end-
user purchaser against defects in workmanship and
materials in it's manufacture for a period of one year from
the date of shipment to the end-user.
Faults arising from misuse, unauthorised modifications or
accidents are not covered by this warranty. If the unit is
faulty, it should be sent in it's original packing to the
supplier or your local ASL dealer, with shipping prepaid. A
note must be included stating the faults found and a copy
of the original suppliers invoice.
THIS PRODUCT WAS DESIGNED, DEVELOPED AND
MANUFACTURED BY :
AMPCO SOUND LAB BV
MAARSSEN (UTRECHT) HOLLAND
INPUT AMPLIFIER
INTERCOM LINE DRIVER
OUTPUT AMPLIFIER
SIDETONE
rejection min. 30 dB (20Hz - 20 Khz)
DIMENSIONS AND WEIGHT
GENERAL SPECIFICATIONS
station bridging impedance > 150 Kohm
Note: 0 dBu = 775 mV into open circuit.
ASL reserve the right to alter specifications without further
notice.