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Summary of Contents for Lectrosonics M185
- Page 1 M185 BELT-PACK TRANSMITTER OPERATING INSTRUCTIONS and trouble-shooting guide LECTROSONICS, INC. Rio Rancho, NM...
- Page 2 OPERATING INSTRUCTIONS ....... . . M185 INPUT JACK WIRING ........
- Page 3 GENERAL TECHNICAL DESCRIPTION The M185 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 input compressor is a low distortion shunt FET compressor operating before the mic preamp.
- Page 4 The input on the M185 accommodates virtually every lavalier, hand-held or shotgun microphone available. Use a Switchcraft TA5F connector on the cord. See the separate sheet titled "M185 Input Jack Configuration" regarding the correct connections for various microphones, and other sources.
- Page 5 CONTROLS AND FUNCTIONS (cont’d) 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 The M185 transmitter is powered by a standard alkaline 9 Volt battery. It is important that you use ONLY an ALKALINE battery for longest life. Standard zinc-carbon batteries marked "heavy-duty" or "long-lasting" are not adequate. 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 Even when limiting is occurring, little or no distortion will occur, due to the high linearity of the limiting circuitry in the M185. The input limiter will cleanly handle peaks up to 20dB above full modulation.
- Page 8 These types of modifications are not shown on the attached instructions. The M185 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 9 TROUBLESHOOTING Before going through the following chart, be sure that you have a good battery in the transmitter. It is important that you follow these steps in the sequence listed. SYMPTOM POSSIBLE CAUSE TRANSMITTER BATTERY LED OFF 1) Battery is inserted backwards. 2) Battery is dead.
- Page 10 SPECIFICATIONS AND FEATURES Operating frequencies: 150 to 216 MHz RF Power output: 50 mW ±15 kHz (max) Deviation: 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 11 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 12 This warranty gives you specific legal rights. You may have additional legal rights which vary from state to state. LECTROSONICS, INC. 581 LASER ROAD RIO RANCHO, NM 87124 USA May 12, 1994...
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