The MSR 4030 is a 1 kW antenna coupler for use when connecting whip or wire antennas to a transmitter designed to match a 50 ohm load from (j5j)30 MHz. Although particularly suitable for use with Mackay transmitters incorporating the MSR 1020 1 kW Linear Power Amplifier, an optional model MSR 6408 control unit is available to facilitate interface of the antenna coupler with other transmitters. The MSR 4030 is designed for easy installation and features an automatically switched series capacitor to provide the capability of matching a wide range of antennas without use of optional external networks or internal field adjustments. Additionally, all the high reliability electronic control circuits are located in a compartment adjacent to the tuning circuits. This "single package" concept eliminates the need for a separate electronics unit and simplifies installation and troubleshooting. The MSR 4030 uses plug-in modular construction and can be quickly disassembled with only basic tools. Built in Test Equipment (BITE) facilites are provided for testing and maintenance of some assemblies without special test equipment. The Antenna Coupler is housed inside a fully gasketed and water-tight case. In this way, it is designed for outside mounting near the antenna. A memory module is provided to expand the capabilities of the basic coupler tuning functions. With this module, the tuning information can be stored automatically and retained in memory for up to 96 communication channels. Upon command, the memory will rapidly guide the MSR 4030 tuning elements to their preset positions without an RF carrier or any manual tuning controls. This feature provides extra convenience and a very rapid method of tuning many frequencies without the necessity of radiating RF power. The Antenna Bypass Kit is available as an option that can provide the user with a convenient method of receiving out of band signals. It is designed to bypass the coupler network during receive so that the tuned circuits will not degrade out of band received signals. Although the MSR 4030 is designed to withstand severe shock and vibration conditions, an optional shock mount kit is available for additional protection. With this kit, the coupler can withstand the severe shock and vibration of the environment as defined by MIL-STD-81OC.