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FMR622S 

 

DUAL NARROW BAND  

SLIDING DE-EMPHASIS DEMODULATOR 

 
 
 
 
 
 

INSTRUCTION BOOK 

IB 1222-22 

 
 
 
 
 

 

Summary of Contents for FMR622S

Page 1: ...FMR622S DUAL NARROW BAND SLIDING DE EMPHASIS DEMODULATOR INSTRUCTION BOOK IB 1222 22 ...

Page 2: ...TABLE OF CONTENTS SECTION 1 0 INTRODUCTION 2 0 INSTALLATION OPERATING INSTRUCTIONS 3 0 SPECIFICATIONS 4 0 FUNCTIONAL DESCRIPTION 5 0 MAINTENANCE 6 0 TUNING PROCEDURES COMPONENET LOCATOR APPENDIX B ...

Page 3: ...ing PMS610 refer to Appendix B of this instruction set for the installation procedure Connect an RG59U cable between the COMPOSITE output of the satellite receiver and the SUBCARRIER INPUT IN on the rear of the FMR622S Terminate the SUBCARIER INPUT OUT with 75 ohms either a resistor or looped through into another unit with 75 ohms resistive termination Rotate the subcarrier SQ Squelch control at t...

Page 4: ... VDC 120 mA PMS610 SIZE MOUNTING This unit requires 1 3 FM Systems PMS610 mainframe power supply which fits into a standard 19 wide rack with 17 13 16 between mounting rails 1 high 10 deep The other 2 spaces in the PMS610 accommodates additional FM Systems 600 series modules The compact power supply in the PMS610 does not require a separate module location as it is beside the three module location...

Page 5: ... U5 provides a low impedance drive for negative feedback to stabilize the gain and operating point of U5 at low frequencies U6 provides 10 dB of gain and buffers the high output impedance of U5 and C141 to feed the following stages AUDIO OUTPUT U7 U8 One half of U8 provides the 75 microsecond de emphasis for the base band audio output and is used to set the drive level to U8 a semi floating fully ...

Page 6: ...retuning If circumstances require that the retuning be done in the field the following procedure may be used TEST EQUIPMENT REQUIRED A Deviation Meter D Distortion Analyzer B FM Generator E Audio Sine wave Generator C Oscilloscope TUNING OF THE BANDPASS FILTER Connect the FM generator set the approximately 1 Vp p at the required sub carrier frequency to J2 sub carrier input Connect the scope probe...

Page 7: ...res better than 0 5 connect the RF output of the FM generator set to 30mV to the sub carrier input of the FMR622S Terminate the subcarrier output with 75 Ohms Connect the input to the distortion analyzer to the wiper of VR131 Left VR231 if right channel The audio level should measure within 3 dB of 0 dBm 1 5 to 3 Vp p Adjust C115 for minimum THD it should be better than 0 7 TUNING THE DE EMPHASIS ...

Page 8: ... center tapped 600 Ohm lead Modulate the subcarrier 100 with 1 KHz Monitor the signal level at the junction of the two load resistors and adjust VR156 for the best null Check levels at T R then should be identical Connecting either T or R to ground should increase the level of the opposite terminal by 6 dB 1 dB Connecting the center tap of the load to ground should have no effect on the level APPE...

Page 9: ...610 power distribution wire 0 025 square connector pins are used usually connected to a multiple jumper daisy chain provided with mating female connectors which connect from one circuit board to the next Power supply return is through the chassis Push any L E D s Light Emitting Diodes straight into the appropriate mounting holes See instructions for the particular module being installed Insert onl...

Page 10: ...conditions but can seriously reduce the ability of the unit to function correctly under other conditions which may be encountered Therefore if you must adjust a control place a mark on it before moving it so that it may be returned to its original setting with reasonable accuracy Disconnect power Replace the top and bottom covers and mount mainframe to rack Reconnect power and check for normal ope...

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