dBm. It uses tunnel diodes, which utilize quantum mechanics theory, to amplify those low signals. The signals from two receivers are sent to a comparator, where they are compared, combined, or used separately, as necessary. The TRC-97 Radio Set is small, as radio sets go. It is housed in a van approximately , and is delicately loaded onto a M1028 pickup truck. A trailer hauling a twin set of parabolic antennas and generator is usually pulled by the truck when it goes on its many maneuvers and deployments in support of the American defense system. The TRC-97 was superseded by a more modern, less maintenance intensive, digital radio set called the AN/TRC-170. Users The TRC-97 was initially made for the Marine Corps to help them with their military operations, such as the Vietnam War. It originally only had only 12 multiplex channels, but when the Air Force decided to use the equipment, they added an additional 12 channels in another module called the baby mux, next to the cabinet that houses the klystron. (This modification caused the equipment to be recognized as the TRC-97A.) Wired to voice channel 1 was a 16 channel teletype multiplexer. The Air Force had been using it for 20 years in the 1980s. There are several military organizations that have used the TRC-97 and TRC-97A. One such organization was the 601st Tactical Control Wing, headquartered in Sembach Air Base, near Kaiserslautern, Germany, which has one of the largest concentrations of Americans outside of the United States. Also the 606 Tactical Control Squadron, Basdahl, GE outside of Bremerhaven, GE on the North Sea. There was also the 626 and 636 Tactical Control Flights along with the 601st, 602nd and 606th Tactical Control Squadrons fell under the 601st Tactical Control Wing, and military personnel assigned to those squadrons often went on deployment to various sites in Germany, thereby providing a show of force during the cold war. The 602nd Tactical Control Squadron was located in Turkheim, Germany, which was a remote village in Bavaria. The nearest military installation was an Army installation in Neu Ulm, Germany. The 602nd Tactical Control Squadron closed in 1985, when the United States agreed to minimize their military presence in Germany. The 728th Tactical Control Squadron was located at Duke Field (Field 3) associated with Eglin Air Force Base located near Fort Walton Fl. The 728 TCS was formerly based at Shaw