User manual

User Manual PS 230 / Issue 1 © 1994 ASL Intercom, Utrecht, Holland.
5
8.0 PARTY LINE, TECHNICAL CONCEPT 10.0 TECHNICAL SPECIFICATIONS PS 230
ASL's PRO Series offers a complete two way ('full duplex')
communications system. current (at 30 V DC) 40 mA quiescent
Users of the system are connected via a 'party line'. 80 mA signalling
Master stations (with built-in power supply), beltpacks, 220 mA at max. output + signalling
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 gooseneck microphone type noise cancelling electret
functions as earth/return. headset mic. impedance 200 ohms
Current drive is used for signal transfer. Each station presence filter +6 dB at 5 kHz
utilises a current amplifier to amplify the microphone signal frequency response 200 Hz - 13 kHz (-3 dB)
and place it on the common audio line where, due to the V electret mic +9 V DC
constant line impedance (situated in the power supply
between XLR pin 3 and 1), a signal voltage is developed
which can be further amplified and sent to headphones or max. load 200 ohms
loudspeakers. max. output level normal 14 V rms (200 ohms)
This principle has three advantages: max. output power normal 0.5 W rms (each can)
- the use of a single audio line allows several stations to binaural 0.16 W rms (each can)
talk and listen simultaneously.
- due to the high bridging impedance offered by each
station, the number of stations 'on line' has no speaker impedance 50 ohms
influence on the level of the communications signal. max. output power 1.3 W rms
- power and audio to the intercom stations use the same
cable.
The Call signal is also sent as a current on the audio line. output impedance > 150 Kohms
It develops a DC potential over the line impedance which
will be sensed by each station and interpreted as a Call
signal. rejection 0 - 30dB adjustable
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
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.
POWER CONSUMPTION
MIC. PREAMP
gain 40 dB - 70 dB (adjustable internally)
HEADPHONES DRIVER AMP
binaural 8 V rms (400 ohms)
SPEAKER DRIVER AMP
INTERCOM LINE DRIVER
max. output current 3 mA rms
SIDETONE
BUZZER
max. SPL 100 dBA
DIMENSIONS AND WEIGHT
width 230 mm
height 88 mm
depth 42/48 mm sloping
weight 1.3 Kg
GENERAL SYSTEM SPECIFICATIONS
intercom line impedance 350 ohms (1kHz)
2.2 Kohms (DC)
intercom line audio level nom. -18 dBu
max. +4 dBu
dynamic range 80 dB
call send signal +2.8 mA
call receive signal threshold +2.4 V DC
supply voltage +30 V DC (12 V to 32 V)
mic mute power interrupt time 0.1 sec
Note: 0 dBu = 775 mV into open circuit
ASL reserves the right to alter specifications without further
notice.