MR-1 02A - Clear-Com
Contents
1. AnD 5090 Td t 079 PSE SCH Invi Oee s 7777 42 HO6E 91 sl Se 507 222 1292. Supply to support the system e 6 MR 102A FIXED INSTALLATION TWO CHANNEL METHOD I 4 WIRES UNSHIELDED IN CONDUIT PIN CONNECTIONS 1 COMMON 2 30v 3 AUDIO NOTE CONDUIT GROUNDED TO MAIN STATION CHASSIS NOTE IF WIRES DO NOT FIT IN STATION CONNECTOR BLOCK USE SONG TON BLOCK VO CONNECT WIRES TOGETHER CONNECT METHOD II 2 2 COND SHIELDED PAIR Suggested Cable Method 1 Belden 8741 Method 2 Belden 8412 or 8413 DOSE te To O II INSTALLATION OF THE MR 102A The MR 102A connects to the inter com system via a five screw termi nal strip designated on the Sche matic as H 1 While making con nections refer to the stick on label adjacent to the terminal Strip on the back of the MR 102A panel it identifies each pin by number and assignment as shown below CH 30 ALBI y 112 4 Designed for permanent installa tion the MR 102A mounts readily in a standard 2 gang electrical outlet box minimum depth 1 3 4 Refer to Figure 1 Interconnect Wiring when deciding how to install the unit After preparing a surface for in stallation route standard two conductor shielded cable from a Main Station Power Supply output connector to the MR 102A s loca tion Connect wire to the termi nals according to the following pin assignments 1 Chassis Ground 2 Intercom Audio Channel A 3 Intercom Audio Channel B H DC 30 volts 5 Common To prevent ground
3. adjust the sidetone once if at all even if other stations subsequently join or leave the intercom system Adjusting the sidetone does not affect the level of incoming or outgoing signals The sidetone control is inside an unmarked hole located above the Volume control The sidetone adjustment is accomplished with a small bladed screwdriver At the factory Clear Com sets the sidetone to be approximately 6 dB lower than the incoming signals Adjust sidetone in the following manner 1 plug in headset 2 turn on mic 3 turn up volume all the way e 4 insert screwdriver through front panel hole and engage the slot on the internal trimpot 5 begin talking while slowly turning the screwdriver When you can barely hear yourself you ll have found the null point Off Mic On Call This 3 position toggle switch provides three functions In the up position the mic in your headset is off In the middle position the mic is on The third position Call is associated with the Visual Signal Cir cuitry that s standard on Clear Com equipment It allows the intercom user to attract the attention of operators who have removed their headsets Signalling other stations is accomplished by momentarily pressing the switch down to the Call position Signalling follows the position of the Channel Select switch for instance if you are on Channel signalling activates the call lights on all stations that are assigned to that channel Call
4. loops and buzzes the common terminal pin 5 should NEVER be directly connected to chassis ground pin 1 Use con duit or a separate wire to inter connect two more MR 102A pa nels If you plan to use only one channel on the MR 102A disable the Chan nel Select switch by jumping Chan nels A and B together on the con nector block and hook the intercom audio line to either terminal A diode in the DC input of each Remote Station protects the circui try against miswiring in the inter connect cables The Remote Sta tion bridges the terminated audio line with approximately 20k ohms MR 102 MOUNTING DIMENSIONS 18 OVERALL 4 5 sovAnE MINIMUM DEPTH 175 III HEADSETS The MR 102A provides a 4 pin male XLR connector for a dynamic head set Its built in headset amplifier can drive one headset to levels greater than 110 dB SPL The mic preamp automatically shuts off when the headset is disconnected thereby eliminating hum pick up and extra neous noise The headset connector pin out as signment is Pin 1 Mic Ground Pin 2 Mic Hot Pin 3 Headphone Ground Pin Headphone Hot To assure proper level and perfor mance the dynamic headset should have the following characteristics Microphone type dynamic Impedance 150 250 ohms Output level 55 dB Headphone type dynamic Output impedance 300 2000 ohms A4F PIN 1 MIC GROUND PIN 2 MIC HOT PIN 3 HEADPHONE GROU
5. Light The amber lamp on the MR 102A will light up when another station which is using the same channel as the MR 102A activates the Call circuit or when you are calling other stations If it is necessary to replace the light unserew the lens cap and remove the bulb its replacement is a 387 bulb V THEORY OF OPERATION The MR 102A incorporates Clear Com s high impedance bridging meth od so it connects to the system without taking appreciable power from the line This enables up to 100 MR 102A s to be connected in one system with only a 6 dB loss in level Each Remote Station consists of 3 basic circuits the listen circuit the talk circuit including side tone and the signalling circuit In the LISTEN circuit signals from the line and the mic pre amp go to the buffer amp where signals are amplified 10 dB then to the vol ume control and then to the head set amp for a final 38 dB of gain Current limiting in the headset amp protects it from shorts In the TALK circuit signals from the mic are amplified 37 dB by a low level pre amp Preamplified signals are sent to the audio line where they re attenuated by 17 dB and to the line buffer amp The line buffer feeds part of the sig nal back to the bridging circuit raising the line impedance to 20k ohms When the mic is turned off the mic pre amp gain is reduced to MR 102A BLOCK DIAGRAM DYNAMIC HEADSET SIDETONE ADJUST unity reducing any no
6. MR 102A Remote Headset Station INSTRUCTION and SERVICE MANUAL 945 Camelia St Berkeley California 94710 510 527 6666 Clear Com 810033 8 15 88 REV B CLEAR COM MR 102A REMOTE INTERCOM STATION OPERATION MANUAL CONTENTS PAGE Introduction to the Remote Station System Installation Headsets Operating Controls Technical Theory of Operation e Parts 11561 6 Specifications iw ILLUSTRATIONS 2 Channel Interconnect Wiring MR 102A Mounting Dimensions Headset Y 1 Headset Extension Cord MR 102A Block Diagram Schematio reser niets emd see EK NOTICE While Clear Com makes every attempt to maintain the accuracy of the e information contained in its product manuals the information is subject to change without notice keke ke taka kakak ka ra tk nk KE RK Xx XX xx tx DOCUMENTATION ADDENDUM 102 MANUAL Kk ERK KKK x KEKE x ox Roe K X kk ox x xoxo KY MIC TO LINE GAIN LEVEL INCREASE d I INTRODUCTION TO THE MR 102A REMOTE STATION e The MR 102A Remote Intercom Station allows two way talk listen commu nieating on two separate chan nels It features our contoured frequency response for excellent Speech intelligibility in h
7. ND Pin 4 HEADPHONE HOT CAUTION DO NOT CONNECT MIC GROUND amp HEADPHONE GROUND TOGETHER A4F Figure 3 HEADSET Y CABLE CONNECTIONS Figure 4 HEADSET EXTENSION CORD SHIELDED PAIR The MR 102A drives two dynamic e headsets with only a slight reduc tion in level Clear Com can sup ply you with Model YC 100 Y Adap ter Cable which allows you to plug two headsets into the one 4 pin connector on the front panel Alternately you may construct your own Y cable we recommend you use Belden 8416 2 conductor 25 gauge or Belden 8734 3 conductor 22 gauge see Figure 3 If desired you may construct an extension cord for your dynamic headset using the same cable spec ified above see Figure 4 Limit the extension to 15 feet or less greater lengths lead to possible capacity coupling between the mic signal and the headset signal which would cause oscillation or a loss in frequency response A4M Note Headset leads do not have 16 be s velded on Beiden 8734 LESS 7 IV MR 102A OPERATING CONTROLS o A B Chan Select This two position toggle switch selects which channel will be used for communicating Volume This knob adjusts the listen level in the headset Sidetone Adj The MR 102A provides a Sidetone control which enables the operator to adjust the level of his her voice as heard in the headset allowing up to 35 dB reduction of acoustical pick up You need only
8. igh and low noise environments The MR 102A works with a standard dynamic headset which it drives to levels greater than 110 dB SPL the unit can support two dynamic headsets if they are connected with a Y cord described later in this manual A recessed sidetone control is included on the MR 102A front pan el It enables the operator to adjust his her own voice level as heard in the headset The station also features Visual Call Signal ling to attract the attention of other intercom operators and to activate the remote paging tions at speaker stations e The MR 102A is designed for perma Clear Com intercom systems MR 102 A INTERCOM STATION HEADSET VOLUME nent installation in a standard two gang outlet box The front panel is charcoal brown brushed alu minum wall plate with the intercom electronics module mounted on the back Only 1 75 depth is required for installation The MR 102A connects to the inter com system with standard shielded cable It provides a clearly labelled 5 terminal strip for intercom and power input In places where conduit is present or where AC interference is not a problem you may interconnect sta tions with unshielded wire or un Shielded cable Bidirectional current sourcing high impedance bridging and low current drain allow up to 100 102A or other headset stations to be connected over one mile of cable with one Main Station Power
9. ise in the input circuitry by 30 dB The SIDETONE control works by in jecting a portion of the audio signal from the mic into the buffer amp The mic pre amp signal feeds through the sidetone volume controi and to the inverting input of the buffer amp Cancellation occurs when the mic signal on the line and the signal from the sidetone con trol are mixed into the buffer amp The cancellation can be varied from full on to a 35 db null The visual CALL SIGNAL is accom plished by impressing a DC voltage on the audio line Pressing Call turns on a transistor applying about 11 volts to the audio line This voltage goes to all Stations on the same channel where the DC is detected by a high gain amp that turns on the Call light The call receive circuit requires only 4 volts from the line to turn on the light The 7 volt difference be tween the send and receive voltages assures positive signalling even on very long lines Various capa citors block DC call voltages from entering the amp circuits REVERSE CMANNEL SELECT TERMINAL PARTS LISTING Part Description Oty Schematic Ref Des 710030 Printed Circuit Module 1 210013 Connector dynamic headset 1 J3 240014 Volume knob 3 4 black 1 P2 390000 Lamp cover amber 11 390001 Light bulb 387 510004 Switch toggle 3 pos S1 510040 Switch toggle 2 pos ER VII MR 102A SPECIFICATIONS AMPLIFIER DESIGN Solid state integ
10. rated circuit amps which include a mic preamp headset power amp and signalling circuit Current limited with short circuit amp reverse po larity protection MIC PREAMPLIFIER GENERAL SPECS Frequency Response 250 Hz 12k Hz Line Level 15dBv max contoured to enhance Sidetone Adj 35dB null to full on intelligibility Call Voltage 11 VDC on audio line Mic Input Impedance 200 ohms Call Light Sensitivity 4 volts Mic Preamp Gain 37dB Signal to Noise TodBv Max Input before Clipping 34dBv Equivalent Input Noise 121dBv Station Bridging HEADPHONE AMPLIFIER Impedance 20k ohm 200 10k Hz Freq Response 150 18 Hz 2 dB Power Required 10 ma quiescent Load Impedance Range 300 2000 ohms 15 ma talking Output Level 20 dBm 26v p p 55 ma signalling 600 ohms Voltage Range 12 32v 28v nominal Headset Level gt 110 dB with standard Clear Com headsets CONNECTORS Distortion 0 2 THD at ik Hz Dynamic Headset 4 pin XLR male Amplifier Gain 38dB Line 5 serew terminal block OdBv is referenced to 0 775 volts RMS PHYSICAL CHARACTERISTICS Dimensions 4 5 11 3 cm square Rear Depth 1 75 4 38 em Weight 7 25 oz 21 kg Suman vos ton oo 2 0 YI INON 31 2 29 NOAVLS ILOW3A Za 39014 ASV DILVWAHIDS 62 EEN ASV UJO26 9 DK av uo5 JoO9D V oe V TAN SON 59999 8724 s Ie fe la ji EM 4227135 240
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