Lectrosonics HMa Plug on Transmitter,100mw, 3-Block tuning, Mic Phantom Power, 2 AA, Frequency  941 - 960 MHz

This unique plug-on transmitter design 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 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 Delrin® to improve the ERP of the antenna.
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
to prevent overload distortion and to maximize the signal to noise ratio. 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 +/-50 kHz deviation for a high signal to noise ratio.
The audio performance of the overall hybrid system is depicted in the graph below. Distortion in the overall system is extremely low over the entire audio bandwidth.

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 to indicate a low battery condition.