GOVERNMENT CONTRACT AWARDS

* XonTech Inc. of Van Nuys won a $5.3-million contract from the Director of Strategic Systems in Arlington, Va., for equipment modification.

* Mission Research Corp. of Santa Barbara won a $4.3-million contract from Hanscom Air Force Base in Massachusetts for research and development.

* H.E. Julien & Associates of Oxnard won a $2.5-million contract from Point Mugu for grounds maintenance.

* California Microwave Inc. of Woodland Hills won a $1-million contract from the Navy in Point Mugu for technical representative services.

* J.I. Garcia Construction Inc. of Fresno won a $731,143 contract from Edwards Air Force Base for property maintenance and repair.

* Lambda Signatics Inc. of Chatsworth won a $454,924 contract from the Army at the Redstone Arsenal in Alabama for aircraft components and accessories.

* Arete Associates of Sherman Oaks won a $448,000 contract from the Defense Special Weapons Agency in Alexandria for research and development.

* Llamas Plastic Inc. of Sylmar won a $226,600 contract from Kelly Air Force Base in Texas for aircraft components.

* Ontic Engineering and Manufacturing Inc. of North Hollywood won a $117,058 contract from the Defense Supply Center in Columbus, Ohio, for mechanical power transmission equipment.