YO-100 The YO-100, and YO-101 scopes matched the FT-101 series trancievers and use the same cabinet as the SP-101 and Landliner speakers. They featured display of transmitted signals in addition to two-tone test audio signal generator. In receive mode, the scopes can monitor audio from the speaker, IF received signal and rtty loop patterns. The YO-100 has a number of tubes with a round CRT, the 101 is solid state with a square window for the CRT.