647

The Tektronix 647A is a 100MHz scope that is designed to operate in a wide range of temperatures. It takes two plug-ins, one for vertical, one for horizontal/sweep. It uses 10-series and 11-series plug-ins. The plug-ins resemble those that go in a 560-series scope, like the 3A3 and 3B2 plug-ins, but they are quite different are not at all compatible. The 647A contains vertical and horizontal amplifiers, whereas in the 560-series, the plug-ins drive the deflection plates directly.

Is it the only scope to use those plug-ins? It is unusual to see only one scope in what appears to be the beginning of a series. Was it discontinued because of lack of demand? What replaced it?