This is a Conductus/Tristan Technologies iMC-303 Squid controller with user's manual. The Model iMC-303 iMAG SQUID controller forms the basis of a powerful and flexible measurement system. Its three channel capability accommodates nearly all laboratory SQUID applications without incurring the cost or complexity of eight-channel designs. A unique feature of the Tristan controller is its ability to simultaneously control both LTS and HTS devices. For the experienced user, the Tristan Multichannel Controller offers complete manual control of all SQUID parameters, including bias level, modulation amplitude, "skew" level, dc flux level in the SQUID (offset), heater and integrator reset. All parameters are easily adjusted using the membrane keypad and a convenient menu-driven interface. Users who want a fully automated system will use the one-touch tuning capability that rapidly and reliably optimize the level of all critical parameters. High-resolution AID convertors and the standard IEEE-488 bus make the iMAG controller ideal for use with computerized data acquisition. Use the rear-panel connectors to monitor the high-level analog outputs. A "fourth channel" input allows you to synchronously digitize your own signal along with the three SQUID signals using the controller's internal AID converter.