Used Lectrosonics UM400a Digital Hybrid UHF Belt Pack Transmitter.

The Lectrosonics UM400a is powered by a single 9V battery and provides a full 100mW output for extended operating range. The housing and belt-clip are machined aluminum, powder coated and laser engraved for ruggedness and legibility. The latest digital/analog hybrid technique is presented in a classic Lectrosonics wireless belt-pack transmitter. 24-bit digital audio is combined with optimized FM to create unprecedented audio quality and RF performance. The RF transmission is an aggressively optimized FM system with +/-75kHz wide deviation for a high signal to noise ratio. The overall system delivers full bandwidth audio frequency response up to 20kHz and the operating range of the finest analog wireless systems.

The innovative servo bias input on the standard 5-pin connector provides a programmable, regulated voltage to accommodate a wide variety of electrets microphones. It is no longer necessary to install resistive pads for some mics to prevent overload of the input stage, divide the bias voltage down for some low voltage mics or reduce the limiter range at minimum gain settings. To simplify wiring connectors, a single configuration for all microphones is now available for the UM400a transmitter input and an alternate wiring configuration works well with all 5-pin inputs on Lectrosonics transmitters. Compatibility with earlier analog Lectrosonics receivers and even some receiver models from other manufacturers is provided by custom firmware emulations built into the DSP code. A simple procedure using the frequency and power switches selects the desired operating mode.