Introduction; General Technical Description - Lectrosonics MM400 Operating Instructions Manual

Thank you for selecting the Lectrosonics MM400 frequency agile UHF miniature
transmitter. The MM400 combines over 80 years of engineering experience with the
very latest components, in a design that addresses the most demanding professional
applications.
The design of the MM400 was the direct result of numerous conversations with users,
staging and touring companies and dealers across the US. The specific concerns and
needs brought up in these conversations led directly to the development of the
operational features offered on the MM400. Two hundred fifty six frequencies are user
selectable in 100kHz steps to alleviate interference problems in traveling venues.
The MM400 is a rugged, machined stainless steel package with a removable, spring
loaded belt clip. 3.3 Volts of bias voltage is available to power electret mics. Level
indicating LEDs are provided on the control panel to make level settings quick and
accurate, without having to view the receiver. The battery compartment accepts AA
alkaline or lithium batteries. The antenna is a detachable, locking ¼ wavelength
flexible bronze cable that connects to a 50 Ohm SMA port on the transmitter.
Only the MM400 transmitter is covered in this manual. Companion receivers are
covered in separate manuals. The transmitter will operate with any 400 Series
Lectrosonics receiver in the same frequency group.
If you have a miniature transmitter marked as a MM200 transmitter, this is a factory
programmed variant of the MM400 that uses the Digital Signal Processor in the
MM400 to model the dual band compander used in the 200 series with the appropriate
compander time constants and frequency division. Since the signals are converted
from analog to digital, processed and then converted back to analog, there is a delay
as with all digital audio systems. This delay is 1.6 mS or an equivalent audio path
length delay of 18 inches. With the exception of the audio processing, all other
comments and instructions in this manual can be applied to either the MM400 or
MM200.
If the unit will be used in a wet environment (possible immersion, perspiration, rain scenes, etc.) – be certain all
connectors have intact gaskets and that a properly sealed Lectrosonics' waterproof mic connector is installed and
used with the microphone.
GENERAL
The 400 system uses 75kHz wide deviation for an extremely high signal to noise ratio. The switching power supplies
provide constant voltages to the transmitter circuits from the beginning (1.5 Volts) to the end (0.85 Volts) of battery life.
The input amplifier uses an ultra low noise op amp for quiet operation. It is gain controlled with a wide range dual
envelope input compressor which cleanly limits input signal peaks over 30dB above full modulation.

INTRODUCTION

GENERAL TECHNICAL DESCRIPTION

Rio Rancho, NM – USA
Frequency Agile UHF Miniature Belt-Pack Transmitter
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