TECHNICAL DATA PACKAGE
Model RMS3OO TW Intercom System Rack Mount Speaker User Station
r1
SECTION
2:
INSTALLATION
2.1
MECHANICAL INSTALLATION
The Model RMS300 mounts in an
EIA
standard 19-
inch equipment rack/enclosure, and is one rack unit
high. Allow a minimum of 4 inches (101.6 mm) for
the panel microphone and controls in front.
Additional depth should be allowed for the cabling in
the rear. There are no ventilation requirements.
2.1.1
Headset Requirements
Dynamic microphone headset type:
50 to 1000 ohm microphone
25 to 1000 ohm headphone(s)
High efficiency headphones are recommended be-
cause less line current is required from the power
supply. Use headphones with an impedance of 25
ohms or greater. Low impedance 8 ohm headphones
are not recommended. Headphones with good
acoustic isolation (20 to 40dB) improve communica-
tion
in
high
ambient noise environments, and allow
the user to use the headphones at a less tiring, lower
i\
volume.
\d
In the headset connecting cable, prevent coupling
between the microphone and headphone leads by us-
ing a shielded, twisted pair for the microphone, and a
separate, twisted pair for the headphones. Do not
allow headphone ground to contact microphone
ground or shield. Tie the shield to microphone
ground or "mic low". The headset cable can be made
longer when the microphone and headphone pairs are
physically separated. The wider the separation, the
longer the cable length which may be used. Esti-
mated maximum usable headphone cable lengths are
as follows:
Single cable,
Two shielded twisted pair:
10 ft. (3 m).
Dual ribbed cable,
Two shielded twisted pair:
30 ft. (9 m).
22
ELECTRICAL
22.1
Power
The RMS300 receives electrical power from either:
(1) a system power supply (26 to 32 volts DC on line
connector pins 2
(+)
and
1
(com) (1 or two channel
operation); or
(2) a local power supply option (14 to 26 volts DC).
A
user station requires
18
to 33 volts to be a 10,000
ohm bridging impedance across the powering line, but
the station can otherwise operate (as in the local
power option) from 12 to 33 volts.
When using a local power supply option, each channel
requires a 200 ohm load. See Figure
1-1.
It is
necessary to do this only once for each channel string.
Model RMS300 current requirements range from 30
to 100
mA,
Since, in (I), above, the power and
communications signals may share conductors, it may
be necessary to overcome power losses by increasing
conductor size over long runs (over 1/2 mile (804
m)). Typical operating distance for one RMS300
station is 1/2 mile (.80
km),
and for one RMS300-L,
1/3
mile (0.53 km) using a normal
#
22
AWG
conductor size.
22.2
Signal
The required number of conductors to interconnect
user stations is as follows (For standard unbalanced
TW
user stations):
#
of Channels
#
of Conductors
*
Using a TW power supply (and possibly
operating on a
TW
system).
**
Using
a
non-TW power supply.
***
Using a
TW
power supply and operating on a
TW
two channel system.
RTS.Systems, Burbank, CA 91506
/
FSCM: 60572 TDP3504
/
Third Edition, Sept. 1989
Page 2-1
(107 pages)
(36 pages)
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