LECTROSONICS WM Watertight Transmitter

The VM Transmitter from LectroSonics is Designed for wet or dusty environments, the WM transmitter features O-ring sealed battery compartments and
input jack, a compression sealed antenna port, and gasket sealed control panel and back cover. Dual AA batteries provide twice the operating time of earlier watertight transmitter designs. Larger membrane switches and
control panel and a highly visible, backlit LCD enhance the user interface.

To meet the demand for both extended operating range and extended battery life, the transmitter offers selectable output power of 50, 100 and 250 mW.
With higher power output, the operating range is improved at the expense of battery life. When range is not an issue, the
power can be reduced to extend the battery life.
The transmitter can be controlled by the LectroRM app for hands free setup and adjustment using audible tones delivered into the microphone from your phone.
The transmitter can be put to sleep to conserve battery power during setup when it is buried deep inside costuming, then awakened for normal operation when the production begins. Other adjustments include frequency,
audio level and control panel lockout.
The DSP-based design works with all Digital Hybrid receivers, and is backward compatible for use with Lectrosonics Mode 3 and IFB.
The input section features servo bias circuitry with voltages being selectable from the LCD to match the requirements of a wide variety of lavaliere microphones.
The bias can also be turned off for use with dynamic microphones. A line level setting is provided for use with signal levels up to 5 volts.
The low frequency roll-off can be adjusted from 35 to 150 Hz. A DSP-controlled analog audio limiter is employed ahead
of the first mic preamp to protect the entire audio chain from overload.
The limiter has a range of more than 30 dB for excellent overload protection and a dual release envelope that makes the limiter acoustically transparent while maintaining low distortion.

Watertight Connections
The input connector is mounted in a recessed opening which provides a captive seat for the O-ring on the microphone connector.
This captures the O-ring allowing it to be tightened firmly.
The antenna is mounted with a compressible strain relief under a flange that presses the strain relief into a
tapered opening for a watertight connection.

Output Isolator
The transmitter RF output circuit includes a specialized RF device called an isolator using a magnetically polarized ferrite to allow RF signals to pass through to the antenna, but block them from coming backward into the transmitter output section.
The isolator greatly reduces RF intermodulation produced in the transmitter output stages when multiple units are used in close proximity (a few feet apart).
The isolator also helps protect the output stage from electrostatic shock delivered to the antenna.
Isolators are common in broadcast and commercial applications, but because of their high cost it is unusual to find them in wireless microphone transmitters.