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 though of as an 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.