Lectrosonics HMa Digital Hybrid Wireless® UHF Plug-On Transmitter

• Accepts microphone or line level signals
• Selectable 5, 15, 48-volt phantom power
• 76 MHz tuning range in 100 kHz or 25 kHz steps for up to 3072 frequencies
• Selectable 50/100 mW output power
• Adjustable low-frequency roll-off
• Powered by two AA batteries
• USB port for firmware updates
• IR (infrared) port for fast setup
• Solid machined aluminum housing

The Lectrosonics HMa Digital Hybrid Wireless UHF Plug-on Transmitter is a unique plug-on transmitter design that will ideally match any microphone or line level source via a standard XLR connector. Phantom power is selectable at 5, 15 and 48 volts, or can be turned off for use with dynamic microphones and line level signal sources.

The design includes a wide tuning range of up to 76 MHz, with tuning steps in increments of 100 kHz or 25 kHz for up to 3072 frequencies. The tuning range covers three standard 25.6 MHz Lectrosonics frequency bands. Each of the standard bands includes 256 different pilot tone frequencies for compatibility with all Digital Hybrid Wireless receivers.

DSP compatibility modes are also included to work with legacy Lectrosonics analog wireless microphone receivers and IFB receivers, as well as some receivers from other manufacturers.

The transmitter is powered by two AA batteries, with status indicated by a multi-color LED. A USB port is provided for firmware updates. An IR (infrared) port is also included to simplify setup with IR enabled receivers.

The input amplifier uses an ultra-low noise op-amp for quiet operation. It is gain controlled with a wide range dual envelope limiter, providing over 30 dB of headroom above full modulation. A 24-bit A-D converter digitizes the audio, then filters supersonic noise above 21 kHz. The resulting signal is encoded with a proprietary algorithm to produce an analog data signal for RF transmission. The underlying RF link is an optimized FM system with +/-75 kHz wide deviation for a high signal to noise ratio.

The antenna is formed between the machined aluminum housing of the transmitter and the attached microphone or cable. It functions as a dipole radiator when attached to a hand-held microphone and somewhat like a ground plane antenna when connected with a cable or plugged directly into a mixer. The conical shaped collar on the input coupler is made of DuPontTM DelrinĀ® to improve the ERP of the antenna in the uppermost frequency bands.

The battery compartment door is hinged to the housing and remains attached to the transmitter when opened. It securely latches in place and applies pressure to the batteries when closed. The two AA batteries are connected in series through a conductive plate on the door.

Setup and adjustments are made with the control panel membrane switches and LCD. The transmitter can be powered up without the transmitter output enabled to allow frequency adjustments without causing interference to other wireless systems nearby. The switches can also be bypassed to prevent accidental changes. Dual color LEDs indicate audio input level and the power LED changes color under low battery conditions.