Airmen 1st Class Cassandra Mallory (left) and Taylor Anliker, 28th Communications Squadron airfield systems technicians, change a circuit card in a radio transmitter at Ellsworth Air Force Base, S.D., March 6, 2012. The circuit card allows the radio to be tuned and calibrated to produce the proper secure frequency. (U.S. Air Force photo by Airman Alystria Maurer/Released)