The TR5821/5822/5823/5823H are compact, inexpensive universal counters with the capabilities comparable to medium-scale counters. These are the It became possible to process data with a self-diagnostic function and various operations (by using TR1644). Since GPIB, BCD (TTL) output, and analog output (D/A converter) are available, these equipments can support various system. TR5821 is a universal counter that can measure frequencies of up to 120 MHz, and can display results in arbitrary form with TR1644 (an extra-cost option). The TR5822 has the same functions as the TR5821 plus a built-in GPIB interface, and the functions of the TR5823 include an ultrahigh-frequency measurement (1.3 GHz) and a burst signal measurement in addition to the functions of the TR5821. The TR5823H is provided with the high-stability oscillator (aging rate: 5 x l0 “8/day) as a standard feature plus the capabilities of the TR5823.