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Lectrosonics M187 Operating Instructions And Troubleshooting Manual

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M187
BELT-PACK TRANSMITTER
OPERATING INSTRUCTIONS
and trouble-shooting guide
LECTROSONICS, INC.
Rio Rancho, NM

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Summary of Contents for Lectrosonics M187

  • Page 1 M187 BELT-PACK TRANSMITTER OPERATING INSTRUCTIONS and trouble-shooting guide LECTROSONICS, INC. Rio Rancho, NM...

  • Page 2: Table Of Contents

    “dangling wire”. This transmitter may be used with a wide variety of audio sources. The multi-pin input jack allows the use of “phantom powered” lavalier microphones with either positive or negative bias voltages. The M187 will also match low imped- ance dynamic microphones and high impedance inputs such as musical instruments or tape decks.

  • Page 3: General Technical Description

    Belt-Pack Transmitter GENERAL TECHNICAL DESCRIPTION The M187 transmitter is comprised of four major functional subsystems: the input compressor, the mic preamp/gain control, the compandor, and the RF transmitter (see block diagram below). The mic preamp is an ultra-low noise type op-amp. Aside from gain control, this stage also adds high frequency pre- emphasis to the audio signal.

  • Page 4: Controls And Functions

    MIC LEVEL INPUT JACK The input on the M187 accommodates virtually every lavalier, hand-held or shotgun microphone available. Use a Switchcraft TA5F connector on the cord. See the separate sheet titled “M187 Input Jack Configuration” regard- ing the correct connections for various microphones, and other sources.
  • Page 5 Belt-Pack Transmitter Since the internal circuits are all tightly regulated and the RF output stage has a separate discrete regulator, the transmitter will continue to operate to a battery voltage of 6.5 Volts. From 6.5 Volts to 6 Volts, the transmitter will still operate, but with degraded performance.

  • Page 6: Battery Replacement

    BATTERY REPLACEMENT The M187 transmitter is powered by a standard alkaline 9 Volt battery. It is important that you use ONLY an ALKA- LINE battery for longest life. Standard zinc-carbon batteries marked “heavy-duty” or “long-lasting” are not ad- equate. They will provide only about 4 hours of operation. Similarly, ni-cad rechargeable batteries only provide 4 hours of operation or less, and will also run down quite abruptly.

  • Page 7: Operating Instructions

    Even when limiting is occurring, little or no distortion will occur, due to the high linearity of the limiting circuitry in the M187. The input limiter will cleanly handle peaks up to 35dB above full modulation. 5) Set up the receiver according to the receiver manual.

  • Page 8: Microphone Cord Termination

    MICROPHONE CORD TERMINATION TA5F Connector Assembly VIEW FROM SOLDER SIDE OF PINS 0.15" Heatshrink Tubing 0.3" Mic Cord Stripping Instructions Caution! Do not allow the shield wire to touch any metal part of the connector shell. The shield wire is the antenna on VHF models and poor operating range will result.

  • Page 9: M187 Input Jack Wiring

    These types of modifications are not shown on the attached instructions. The M187 uses the shield of the microphone cord as the antenna. Other brands use a “dangling wire” to emit the RF from the transmitter. There is really no difference between these two approaches, with respect to the effect of the RF on the microphone capsule.
  • Page 10 Leaded capacitors: P/N 15117 Leadless capacitors: P/N SCC330P All Lectrosonics lavalier mics are already bypassed and do not need any additional capacitors installed for proper operation. BODY GROUND Caution - When wiring the connector, do not use the connector body for any electrical connections. A common mistake is to use the connector body as an audio ground.

  • Page 11: Troubleshooting

    Belt-Pack Transmitter TROUBLESHOOTING Before going through the following chart, be sure that you have a good battery in the transmitter the red power LED on the transmitter panel should glow brightly. SYMPTOM POSSIBLE CAUSE TRANSMITTER BATTERY LED OFF 1) Battery is inserted backwards. 2) Battery is dead.

  • Page 12: Specifications And Features

    SPECIFICATIONS AND FEATURES Operating frequencies: 150 to 216 MHz RF Power output: 50 mW Deviation: ±15kHz (max) Spurious radiation: 55 dB below carrier Equivalent input noise: -126 dBV Input level: Nominal 2 mV to 300 mV (before compression) 30 Volt max. input level (including limiter) Input impedance: Selectable for 500, 1K, 10K Ohm Input compressor:...

  • Page 13: Service And Repair

    There are no adjustments inside that will make a malfunctioning unit start working. LECTROSONICS service department is equipped and staffed to quickly repair your equipment. In-warranty repairs are made at no charge in accordance with the terms of the warranty. Out of warranty repairs are charged at a modest flat rate plus parts and shipping.

  • Page 14: Warranty

    This warranty does not apply to used or demonstrator equipment. Should any defect develop, Lectrosonics, Inc. will, at our option, repair or replace any defective parts without charge for either parts or labor. If Lectrosonics, Inc. cannot correct the defect in your equipment, it will be replaced at no charge with a similar new item.

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