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GENERAL TECHNICAL DESCRIPTION 

The  FM-AV4  Portable  Wireless  Sound  System  consists  of  an  FM875  combination  wireless 
receiver/amplifier/speaker  with  a  rechargeable  battery  pack,  an  M175  belt-pack  transmitter  and  a 
microphone.  Optional  microphones,  transmitters  and  accessories  are  available.  These  items  will  be 
discussed elsewhere in this manual. 

The  FM-AV4  features  a  VHF  high  band  wireless  microphone  system  with  excellent  operating  range, 
freedom from "dropouts" and interference from other radio transmissions.  The built-in receiver provides 
high selectivity and sensitivity with an automatic squelch circuit which requires no adjustment by the user. 
The M175 belt-pack transmitter uses the microphone cord as the antenna which eliminates the dangling 
wire  antenna  found  on  many  other  transmitters.  The  transmitter  features  a  gain  adjustment  to  properly 
match the level of your voice and the microphone. 

The  FM875  receiver/amplifier  offers  inputs  and  outputs  to  accommodate  virtually  any  application.  In 
addition  to  the  wireless,  there  is  an  auxiliary  microphone  input  for  dynamic  microphones,  a  balanced, 
microphone  level  audio  output,  and  both  "aux  in"  and  "line  out"  jacks  for  external  tape  recorders.  This 
allows the FM-AV4 to interface with other sound systems, video taping equipment or any type of "house" 
sound  system.  This  versatility  lets  you  use  the  wireless  microphone,  a  hard-wired  microphone,  a  tape 
recorder and the house sound system all at the same time. 

The FM875 is powered by built-in rechargeable batteries and will easily operate for over 12 hours after an 
overnight charge.  The sound output will cover an audience of several hundred people. 

RECHARGEABLE BATTERIES 

It is  very important  to recharge  the battery  pack immediately  after the  unit is used.  The  battery pack  is 
charged  by  plugging  the  CH-40  charger  into  the  jack  labeled  CHARGE  on  the  control  panel  of  the  unit. 
Connect the charger into a standard 110 Volt, 60Hz AC outlet.  The green lamp beneath the jack will light 
as long as the batteries are charging.  When the batteries are almost completely charged the green charg­
ing  light  will  go  out.  You  may  leave  the  charger  plugged  in  after  the  green  light  has  gone  out  with  no 
danger of damage to the system.  In fact, we recommend charging the system whenever it is not in use, 
then the system will always be "ready to go". 

Operation  is  possible  while  charging  the  batteries  with  the  supplied  CH-40  charger,  however  since  the 
amplifier consumes more power than the CH-40 charger can supply, the batteries will recharge faster if you 
turn the amplifier power off while charging. 

The battery pack should be recharged for 16 hours at least once every six months even when the unit is 
in storage and not being used. 

In many cases, a battery that seems to be dead may be saved by prolonged charging.  As much as 10 
days of continuous charging may be necessary to restore the batteries after they have been left for several 
weeks  or  more  in  a  "discharged"  condition.  The  charge  lamp  may  not  light  up  during  the  first  part  of  a 
prolonged charging period. 

Содержание FM-AV4

Страница 1: ...FM AV4 PORTABLE WIRELESS SOUND SYSTEM OPERATING INSTRUCTIONS and trouble shooting guide LECTROSONICS INC Rio Rancho NM ...

Страница 2: ...wer supply and the high quality of the audio output set this system apart from any other portable PA system on the market This manual covers the FM875 RECEIVER optional microphones and transmitters TABLE OF CONTENTS INTRODUCTION 2 GENERAL TECHNICAL DESCRIPTION 4 RECHARGEABLE BATTERIES 4 CONTROLS AND FUNCTIONS 5 TRANSMITTERS 7 SYSTEM SETUP 9 OPERATING TIPS 10 OPERATING INSTRUCTIONS 11 MICROPHONE CH...

Страница 3: ...ound system all at the same time The FM875 is powered by built in rechargeable batteries and will easily operate for over 12 hours after an overnight charge The sound output will cover an audience of several hundred people RECHARGEABLE BATTERIES It is very important to recharge the battery pack immediately after the unit is used The battery pack is charged by plugging the CH 40 charger into the ja...

Страница 4: ...ll go out when the batteries are discharged CHARGE LED Lights when the unit is being charged This green led will go out when the batteries are fully charged OMNI BUS IN OUT An RCA phono jack that functions both as a line level input and line level output This omnibus jack is primarily used for interconnecting several FM875s together for simultaneous operation This jack can also be used with a tape...

Страница 5: ...of the MIC OR AUX IN and the AUX IN inputs MIC OR AUX IN This jack is a standard 1 4 phone jack and will accept a dynamic microphone WIRELESS MIC VOLUME This control adjusts the volume of the built in wireless microphone system knob does not affect the MODULATION LEDs located near it This MODULATION LEDs The 20 and LIMIT Leds continuously indicate the modulation level audio level of the received s...

Страница 6: ...ch should be left in the off position when the transmitter is not in use When the switch is in the on position the battery will be drained even though the transmitter is not being used The BATTERY INDICATOR LAMP will light when the transmitter is turned on and will stay lit as long as the battery is good As the battery voltage drops the lamp will grow dim and finally go out The MIC LEVEL is a rece...

Страница 7: ...time remaining When the battery voltage is too low for proper transmitter operation the sound from the wireless system may be distorted intermittent or totally absent When the transmitter is first turned on the lamp may light for a short while even with a bad battery It is good practice to check the brightness of the lamp after the transmitter has been on for several minutes and to note the bright...

Страница 8: ...th the direct signal If the direct and reflected signals are out of phase with each other as depicted in the figure below a partial or complete cancellation of the received signal will occur The result will be a drop out A drop out sounds like either a hum or hiss or in severe cases may result in a complete loss of the sound when the transmitter is positioned in certain locations in the room Movin...

Страница 9: ...e FM875 Feedback is generally more of a problem when using lavalier lapel type microphones than with hand held or headset type microphones because the microphone is farther from the mouth See below for more details on feedback 8 The standard FM AV4 system includes an M140 cardioid lavalier microphone This directional microphone will minimize background noise and provide resistance to feedback when...

Страница 10: ...on in the same location it will be in during actual operation The microphone should ideally be within 6 to 10 inches from the mouth to minimize feedback 9 A small screwdriver is supplied with the transmitter The screwdriver is used to adjust the audio gain of the transmitter to match the microphone with your voice The adjustment is made while observing the MODULATION lamps on the FM875 control pan...

Страница 11: ...k connect the AUX IN on the unit with the AUDIO OUT line level on the tape recorder Set the AUX VOLUME at about 6 then adjust the volume control on your tape player to get the desired volume Not all tape recorders will work with the FM AV4 Low cost tape recorders may not have line level inputs and outputs required for quality recording and playback CONNECTING INTO HOUSE SOUND SYSTEMS 1 Connect MIC...

Страница 12: ...75 using a standard microphone cord MM 16 or MC 16C The M121S is available as an accessory item HM142V This single band headset microphone is normally worn on the head but can also be worn around the neck for hands free operation It provides maximum gain before feedback since the microphone is very close to the user s mouth The built in volume control helps control feedback in difficult environmen...

Страница 13: ...ransmitter gain control set much too low 4 Transmitter audio muted Check to see that the audio is not muted on your transmitter if this feature is available on your model transmitter NO SOUND BUT RECEIVER MOD LEVEL LEDs ARE ON 1 WIRELESS or AUX VOLUME control turned completely down 2 Sound system or recorder input is turned down 3 Defective speaker DISTORTED SOUND 1 Transmitter gain audio level is...

Страница 14: ...Wind Screen RK 119 Wind Screen RK 142 Wind Screen USE Replacement With locking micro plug With locking micro plug For hand held use plugged into the AUX MIC INPUT jack of the FM875 cord not supplied 16 ft coiled cord 1 4 male to male for M121S Straight cord 1 4 male to male for M121S 36 RCA male to male for interconnecting HI LEVEL IN and OUT jacks with other equipment For M121S microphone For M14...

Страница 15: ...n Below the noise at all input levels Spurious image rejection Greater than 100dB M175 SERIES TRANSMITTERS Operating frequencies 169 to 186 MHz RF Power Output 50 mW Deviation 15kHz Spurious Radiation 50dB below carrier Frequency Stability 0 005 Equivalent Input Noise 123dB Input Sensitivity 8mV to 1 6V for full modulation Input Compressor Soft Compressor 12dB range Electret Bias 5 Volt DC positiv...

Страница 16: ...n exact quotation We will be happy to quote approximate charges by phone for out of warranty repairs RETURNING UNITS FOR REPAIR You will save yourself time and trouble if you will follow the steps below A DO NOT return equipment to the factory for repair without first contacting us by letter or by phone We need to know the nature of the problem the model number and the serial number of the equipme...

Страница 17: ......

Страница 18: ...evelop we will at our option repair or replace any defective parts without charge for either parts or labor If we cannot correct the defect in your equipment we will replace it at no charge with a similar new item We will pay for the cost of returning your merchandise to you This warranty applies only to items returned to us shipping costs prepaid within one year from the date of purchase This war...

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