OA47 Germanium signal diode. Package: standard glass DO-7 case Download OA47/90/91 datasheet: note: these are dating from the 60's /70's and so not cheap modern chinese imports. Status: NOS (New Old Stock) in perfect condition (STC / Mullard) ex aviation stores / GPO, Individually Tested components: YES : low Vf, 0.3 - 0.37 typical indicating Germanium. RoHS compliant: no *** back in stock as of Dec 2022 after many month of searching - guaranteed the real thing ! ****