Produced from 1986 to (?)
The Tektronix 1720 is a Television Vectorscope for the NTSC video standard. The 1721 is the PAL and the 1725 is a multi-standard sister model.
The 1720 can be coupled to a 1730 Waveform Monitor.
The standard Tektronix 1720 uses a 154-0983-00 CRT, the Opt. 74 instrument uses a 154-0983-16 CRT.