The SD-20 Sampling Head is a high-performance sampling head that can be installed in the 11800 Series Digital Sampling Oscilloscopes, the SM-11 Multi-Channel Unit, and the CSA 803 Series Communications Signal Analyzers. The SD-20 Sampling Head provides the following features: ■ A one-channel feed thru path for signal acquisition and measurements. ■ A 17.5 ps acquisition rise time. ■ A 20 GHz typical bandwidth for high-speed signal capture. ■ Displayed noise is 750 |jVRMs typical without smoothing and 350 |jVRMs typical with smoothing on. ■ Precision 3.5 mm connectors. ■ A SELECT CHANNEL button for quick trace acquisition and selection from the sampling head front panel. As shown in Figure 1, the SD-20 Sampling Head has a single acquisition channel with a feed thru or loop path (labeled LOOP on the front panel), an INPUT connector, and a FEED THRU connector (both of these connectors are also located on the front panel). The strobe drive signal from the instrument controls the timing of the strobe assertion to the Acquisition system.