The ORTEC 9301 and 9301S Fast Preamplifiers are designed for use in fast timing system applications. They feature very low noise and fast risetime to facilitate precise timing measurements. Their small size and light weight permit them to be used in close proximity to the detectors they serve, and this minimizes noise in the output signals. The two Preamplifiers are identical except for the mating power connector at the remote end of the power cable. Although the reference in this manual is to the 9301, the instructions also relate to the 9301S. The 9301 can be used with photomultipliers, electron multipliers, and other detectors that are employed in photon counting or ion counting techniques. When the preamplifier is connected to the detector, the 50S input impedance of the 9301 becomes the load resistance for the detector output current pulse. The risetime of the 9301 output pulse is <1.5 nsec and the voltage gain is 10. This combination ensures the user that each input pulse from the detector will rise quickly through a normal discriminator threshold for a precise timing identification. The voltage gain of 10 also enhances the signal-to-noise ratio for the system. Power for operation of the 9301 must be obtained from either the instrument to which its output pulses are furnished or from an ORTEC 114 Preamplifier Power Supply. A 10-ft power cable is built into the unit and terminated with an Amphenol 17-20090 plug. The Amphenol plug is compatible with the Preamp power source on a 114 Preamplifier Power Supply, a 9302 Amplifier/Discriminator, or any ORTEC NIM-standard amplifier module. For the 9301S the power cable is terminated with a DIN plug, compatible with the ORTEC Brookdeal 5C1 Photon Counting System.