In contrast to the 3S6 which uses external sampling heads, the S-311 contains two samplers internally, like the 3S76 or 3S1. However, unlike the 3S76 and 3S1, the S-311 gets its signal inputs via BNC connectors on the rear panel. The input impedance of each input is 50 Ω.
When the S-311 is inserted into the mainframe, its BNC input connectors must be manually connected, as they are not designed to pair with a corresponding connector in the plug-in bay bulkhead. The 567 mainframe has holes in the plug-in bay bulkhead at the location of the signal input connectors and programming connector of the S-311.
The remote programmability of the S-311 typically involves a Type 262 programmer. Remote programming can control the mV/div, voltage offset, and mode, i.e., channel A, channel B, or dual-trace. The Type 262 controls the DC currents in the coils of six reed relays in the S-311.
The S-311 can be thought of as a 3S76 with remote programmability, connectors on the rear, no delay, and no trigger pickoff. Component numbers are the same in the two models. The S-311 and 3S76 both have 0.4 nanosecond risetimes. The sampler in the S-311 uses four Tek-made GaAs diodes.
The S-311 does not contain a signal delay. The BNC signal input connectors on the rear panel of the S-311 are connected by short coaxial cables to the sampling bridge.
Rear view from underneath of 567 plug-in bay bulkhead. Holes allow for S-311 signal input and programming signal connections.