RTS BP320 Instruction manual

MODEL BP320
Portable Belt User Station
TECHNICAL
DATA PACKAGE
RTS '"
9300-3507-00 Rev A 1/95

/-
TABLE OF CONTENTS
( ) PROPRI~ARYNOTICE ..................................................... ii
COPYRIGHTNOTICE
..................................................... ii
......................................................... PATENTNOTICE ii
UNPACKING
AND INSPECTION ................................................ ii
RETURNSHIPPINGINSTRUCTIONS
............................................ ii
SECTION 1; DESCRIPTIONAND SPECIFICATIONS .................................
1-2
1.2 HEADSETREQUIREMENTS .............................................. 1-4
1.3 BP320 SPECIFICATIONS
................................................ 1-4
...............................................
SECTION 2: INSTALLATION 2-1
2.1 ELECTRICALINSTALLATION / GROUNDING ................................... 2-1
......
2.2 ELECTRICALINSTALLATION / POWER ....................................... 2-1
2.3 ELECTRICALINSTALLATION
/ SIGNALS ...................................... 2-1
2.4 ELECTRICALINSTALLATION
1 CROSSTALKCONTROL .............................
2-2
2.5 ELECTRICALINSTALLATION
/ MOISTURE / CONTAMINATIONPROTECTION ............... 2-2
2.6 ELECTRICALINSTALLATION
/ HUM PREVENTION ............................... 2-2
2.7 USER STATION CONNECTIONS
........................................... 2-2
SECTION 3: OPERATION ................................................. 3-1
3.1 OPERATINGCONTROLS ................................................ 3-1
SECTION 4: LIST OF' DRAWINGS ............................................ 4-1
Page iii

SECTION 1: DESCRIPTION & SPECIFICATIONS
1.1 DESCRIPTION
The Model BP320. a portable belt pack stereo user
station,
is a component used in the TW Intercom
System. Each user station
is a communicationsunit
alonga multi-unit conferencebus.
The System Concept Block Diagram, Figure
1-1,
illustrates a user station interconnection, and user
station connection tothe systempower supply. User
stationinterconnection canbe:
1) Centrally wired, with each cable coming from a
centralpoint or,
2) distributed, where all the user stations are
looped together fromone to another, or
3) a combinationof both.
Thecentrallywired interconnectionnot only reduces
interchannel crosstalk but also allows for easier
expansion into an assignablechannel, multi-channel
system.
i-)
v
The BP320 Block Diagram, Figure 1-2, illustrates a
user station functional components, inputloutput
connectionsand controls.
TheBP320 User Stationhas the followingfunctional
components:
a microphone preamplifierwith limiter,
anelectronicmicrophone switch,
two electronicchannel delegateswitches
two "bilateralcurrent source"linedrivers,
two listenvolumecontrols (dualconcentric),
twoheadphone amplifiers,
a stereolmono switchand
a channelselectorltalk delgateswitch.
ThemicrophonepreamplifierPimiter:
1) convertsthe small microphone signal to a strong
linelevelsignal,
2) conditionsthe signalstrength from loud and soft
talkers tobealmost thesameand
3) sends the signal to the line via the microphone
switch. The microphone switch transfers the
signalto the two electronic talk switches. These
two switcheseach drive a bilateral current source
for channels
1 and 2 respectively. A "bilateral
current source" adds signal to the line without
affecting any signals already
on the line. The
channel selector switch selects on which
channel@) the user will talk and listen. The
BP320has thecapabilitytotalk oneither orboth
channels without connecting the channels
together.
- Each "bilateral current source* also
extractsthelisten signalfrom its lineand sends it
to the respective headphone amplifier and
volume control. Some of the user's own voice
signal ("sidetone") is also fed to the headphone
amplifier. Each headphone amplifier output
drives the user's headphones. The monaural
switchallows a combined signal tobe
fed to each
of the headphone amplifiers so that a single
earphonecan hearboth channels.
The user station voltage regulator takes power
fromchannel
1 regardlessof the channel selector
switch setting (exception: local power option
units). Theregulator not only supplies regulated
power to the user station, but also prevents
unwanted interaction between the user station
and the intercom line supplying power. The
BP320 call light option works in a special way:
Thr transmitted call light signal follows the
channel delegate switch and may appear on
either or both channels. A call light signal on
either channels triggers the BP320 call light
receiver.
The BP320 User Station has four inputloutput
connectors:
1) DYNamic MICrophone type HeaDSeT or
handset.
2) Line INPUT (ties the station to the intercom
line.)
3) LOOPEXTension (allows another station to
access the line through the first station), (also
calledloop-through).
4) Accessories/ExternalControls allows:
1) Remotemicswitch (orfoot switch)
2) Localpowering,and
3) Stereo program input.
Page 1-2

The BP320 User Station has the following controls,
which aredescribedin Section3:
1) CHannel select switch
2) A latching-action MICrophone ON-OW toggle
switch.
3)
A momentary-action MICrophone ON-OFF
pushbutton switch
4)
A dual concentric headphone VOLUME
control.
5) CALL LIGHT switchJindicator (Call Light
Option).
1.2
HEADSET REQUIREMENTS
A wide range of headsettypes may beused:
Dynamicmicrophone headset type:
50to 1000ohm microphone
25to 1000ohm headphone (s)
High efficiency headphones are recommended
because less line current is required from the power
supply. Use headphones with an impedance of 25
ohmsor greater. Low impedance
8 ohm headphones
are not recommended. Headphones with good
1.3 BP320 SPECIFICATIONS
Input DCvoltage:
DC Current
Quiescent
Operating
Impedanceacrossline:
Ambient Temperature Range
Noisecontribution
to 200ohm line:
Microphone Preamplifier
Input impedance
SourceImpedance
Maximum Input Level
Voltagegain:
FrequencyResponse
acoustic isolation (20 to 40 dB) improve
communication in high ambient noise environments,
and allow the user to use the heaphones at a less
tiring lowervolume.
In the headset connecting cable, prevent coupling
between the microphone and headphone leads by
using 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"miclown. 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.
Estimated maximum usable headphonecable lengths
areas follows:
-Singlecable,two shielded twisted pair:
10feet (3.05 m).
-Dualribbed cable, twoshieldedtwisted pair:
30feet (.I4 m).
-Separate cables,shielded twisted pair in each:
50feet (15.24
m).
-Balanced microphoneinput:
up to 100feet (30.48 m).
20 to 35 volts DC, operating from -200 to +36 volts DCwithout
damage
10to
40 milliamps
50milliamps, typical (wn5ohm headphones)
100milliamps, typical(wJ8ohm speaker)
75miliamps typical
10,000ohms typical,2000ohmsworst casedynamicoperation
Operating: 0°Cto60°C
Storage: -55°C to 125°C
OneUnit: -75dBu
Ten Unit: -67dBu
470ohms
200ohms,nominal
150millivolts
54dB
100
Hz to 10,000Hz, +3dB
Page 1-4

SECTION 2: INSTALLATION
2.1 ELECTRICAL INSTALLATION/
GROUNDING
All console, rack and wall mounted user station
chassis shouldbe connected to earthground or power
line safety ground, but the TW Intercom System
circuit ground should not be directly connected to
"earth" or "chassis" ground. Each user station is
bypassed to its own chassis via a 0.1 microfarad
capacitor to prevent interferencefrom radio stations.
The power supply has a bleeder resistor from circuit
ground to chassis ground (22 kilohms) to prevent
a
buildup of voltage across the system capacitance. If
the system has no RTS power supply, install a bleeder
resistor at a central point in the system.
There aretwo advantagesto not "earth"groundingthe
circuitground:
1) The system continues to operate during an
accidental grounding since this can be tolerated by
the systemuntilit can be cleared.
2) Earth currents from other equipment are
prevented from introducing noise into the
TW
Intercom System.
Portable user stations should not arbitrarily be
taped or fastened to metal structures. Grounding
the case of the user station to an arbitrary
structure may introduce large noise voltages due
to local ground currents or the due to the
completion of a "ground loop antenna". Always
clear
all earth grounds from the RTS TW
Intercom System circuit ground. The only ground
should be through the 22 kilohm resistor in the
power supply.
TheBP320 receives electricalpower from either:
1)
A system power supply (26 to 32volts DC on line
connector pins 2
(t) and 1 (corn) (2 channel
operation) or
2) A local power supply option (12 to 18volts
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 12to
33 volts. Model BP320 current requirements
range from 20 to 50
mA; BP320-L, from 30 to 60
mA. Since, in (I), above, the power and
communicationssignals shareconductors, it may
be necessary to overcome power losses by
increasingconductor size over long runs (over 1/2
mile (804.67 m).
Typical operating distance for
one BP320 station is
1 mile (1.609 km) using a
normal #22 AWG conductor size; for a BP320-L,
3/4 mile (1.207
km).
23 ELECTRICALINSTALLATION/SIGNALS
The required number of conductors to interconnect
user stations is-asfollows: (For standard, unbalanced
TW user stations)
Number of Channels Number of Conductors
Use shielded cable to interconnect user stations in
areas of possible electricalinterference,(areas suchas
those near: digital equipment, high current primary
power conductors ("mains"), transformers,
transmitters and lampdimmers).
Most two channel applications may use either
standard microphone cable (for convenience) or two-
twisted-pair cable (considerably less expensive than
microphone cable). Standard wire size for the
TW
Intercom System is #22 gauge wire for
interconnection. For permanent installations it is
recommended that each channel should have
individuallyshieldedtwisted pair of at least #22 gauge
wire, such as Belden #8723 for 2 channels. For 3
channel installations using XLR type connectors, a
cable of
3 individually shielded wires such as Belden
#8733 may be used (using the 3 drain wires as circuit
ground. For 3 channel installations using terminals
blocks or tag strips, a cableof 3 twisted shielded pairs
such Belden #8777 maybe used (using the 3 drain
wires and one each of the three pair as circuit
ground). This
will reduce interference and help
maintain a low crosstalk figure between channel.
Connect the shield to system common
but do not tie
the shield to chassis, earth or connector shell
ground.
Page 2-1

Figure 3-1
Front Panel
Page 3-1

1
SECTION 4: LIST OF DRAWINGS
I
I RTS
, Document
No.
-
AS1428 Assembly Diagram, P.C.B CC-501Layout
SD1431 SchematicDiagram,Model BP501&BP320 User Stations3
SD1470 ServicingDiagram,Light SignallingCircuit, CC-18SL,Phase
3 Cod~guration
Page 4-1

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SWITCH
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Ib. BP-320 IS T#E NEW MODEL NO FOR THE BP-SO1
15. SEE SHT Z
14. SEE PAGE 4
13. SEE PAGE 3-
IZ.TH\S SLUEMATIC APPLIES TO AW 1451F(CC:SOIF).
11. ON PREVIOUS BOARDS, CC-501 E, THIS POINT
I5 CONNECTW TO I2 V..
TEST FREQUENCIES: ICO hr,lkHzASD lOkrlr (r3d8).
SET LIMITER POT WITH TEST LWlTCrl .N 0.3 P05*TIOh,
AND FREQUENCY AT IkHr..VOLUME SATM'N.
9.CALL LlqHT OPT TEST DATX. 20.oM)-'O.IOOkHZATI~O\rpp
ME43JFLED ATTHIS POINT. USETZSTJ14 IN NOTE.
IO.OSE.TESTJ~~
AND TEST SETUP FORVOLTAGE
.~.€~DI~FOR CALL UGH? OPTION TESTS ,SET
VOLTM,E ~hl TEST POWEP SUPPLY BEWEEN lav mc
-5 Z8V DC .SET CHANNELSELECT FOR CHANNEL 7..
B.CUTTAQLE TRACES (USED FOR OPTIONS) ARE
SHOWN:
QUIESCENT
WRRENT-AO~A;@~SL = 400-v).
DYNAMIC CURRENT: 40mA
to IOOmA(V~51=YlOmVtol~V).
6. ALL TEST VOLTAGES AND CURRENTS, f. 10%.
4
INPUT VOLTAGE RANGE AT EXTERNAL POWER
oINPUT, J4-I: AS SHOWN, STANDARO-FOR
lt.84
VOLT INPUTS SUCH AS AUTOMOTIVE AND AlRCRm
DC POWER; SPECIAL-LOW VOLTAGE WTTERY
CONF~GURAT~ONFOR
II to 15VOLT INPUTS:
CUT TRACE
AT^ JUMPER API TO BPI.
@ MINIMUM VOLUM~ OPTION: CUT TRACE^),
ADD Re9 AND/OR R47
.. -
2. CAPACITANCE VALUES ARE SHOWN:
MICROFARADS/VOLTS
I. hLL RE5,STORS ARE CARBON FILM, ~Vf&TT,iS'/.
UNLESS OTHERWISE SPECIFIED:
.i
NOTES:
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