All tubes new, military equipment and have "OTK" mark. Near equivalent: 837 and PK44. The tube is manufactured by Foton, Tashkent, Kazakhstan (new factory is Ulyanovsk).
New Old Stock * No Longer available for export MFR: VSI (Russia) SKU: 837
Designed for applications critical as to leakage under high humidity. New old stock * New In Box * No longer available for export. MFR: GE, Sylvania SKU: 1P40
Radiation cooled Twin Tetrode designed for push-pull Class C operation at frequencies up to 1000 Mhz. New Old Stock * No longer available for export. MFR: Amperex * Made in Holland Limited 90 Day Warranty SKU: 7377