Built as a kit from Heathkit. Build was no problem, built in tuning aid. Functioned only if had good antenna. It would take a long time for it to lock on to one of the WWV 2.5, 5, 10 and 15 MHz signals from Colorado. The device wold provide a display of the exact time to 1 tenth of a second. It also provided a 10 MHz reference signal for use by devices that had that optional input. Lock function required it to scan for receivable WWV signal, then decode the transmitted coded signal. When it eventually locked, then it wold display the exact time and provide the 10 MHz signal. If it lost lock, it would have reinstate scan. If lock was held long enough, the internal ref oscillator would be auto trimmed, providing an accurate clock with reduced accuracy. Used it for many years as my main station clock.