Tektronix 492P Spectrum Analyzer Opt 1,2,3 GPIB +Cover Cal Chkd Firmware: 1.7 Tektronix 492P Tek Spectrum Analyzer Opt 123 GPIB with Cover Works Tektronix 492PGM 21 Mhz Spectrum Analyzer open Tektronix 492PGM Programmable Spectrum Analyzer ...