Used Lectrosonics Digital Hybrid Wireless UHF Belt Pack Transmitter, Frequency Block 25 (640.000-665.500MHz)

The LMa combines an excellent feature set with superb performance in a classic Lectrosonics wireless belt-pack transmitter at a modest cost. 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 audio signal to noise ratio and wide dynamic range. When matched with a Lectrosonics digital hybrid receiver, the system will deliver a full bandwidth, flat audio frequency response up to 20kHz with extremely low distortion.

Compatibility with earlier analog Lectrosonics receivers and even some receiver models from other manufacturers is provided by firmware emulations built into the DSP code. A simple procedure using the frequency and power switches selects the desired operating mode.

The innovative servo bias input and standard 5-pin connector provides a programmable, regulated voltage to accommodate a wide variety of electret 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, optimized for the LMa, is now available for all microphones. An alternate wiring configuration is also available that works well with the 5-pin inputs on the LMa and earlier Lectrosonics transmitters.

A DSP-based pilot tone system generates one of 256 different ultrasonic tones between 25 kHz and 32 kHz to ensure that the receiver remains muted (squelched) until it receives the pilot tone from the matching transmitter. Even when a competing RF signal is present on the carrier frequency, the receiver will remain squelched. The pilot tone squelch also eliminates noise and interference from spurious RF generated by other transmitters in the same multi-channel system.

Digital Hybrid Wireless is a revolutionary new patented design that combines digital audio with an analog FM radio link to provide outstanding audio quality and the extended operating range of the finest analog wireless systems. The design overcomes channel noise in a dramatically new way, digitally encoding the audio in the transmitter and decoding it in the receiver, yet still sending the encoded information via an analog FM wireless link. This proprietary algorithm is not a digital implementation of an analog compandor. Instead, it is a technique which can be accomplished only in the digital domain, even though the audio inputs and outputs are analog signals. The process eliminates a compandor and its artifacts.

The LMa is powered by a single 9V battery and provides 50mW of RF output for extended operating range. The battery door rotates to open and close and remains attached to the transmitter housing. Alkaline, rechargeable LiPolymer and lithium battery types may be used. The housing is machined aluminum, powder coated and laser engraved for ruggedness and legibility. The battery door and control panel are also constructed of machined aluminum, with a rugged anodized finish.

A circulator/isolator in the output stage blocks external RF signals that arrive at the antenna from entering the output amplifier. This greatly reduces intermodulation that otherwise could be generated in the output stage. The antenna is a super rugged flexible whip made of galvanized steel. A detachable spring wire belt clip is supplied with the unit.