Russian 5C4M kenotron tube, direct-filament, two-anode. Designed for rectification of alternating voltage. Half 5C3S. Equivalent of the 5Z4, 5Z4G, CV1863, GZ30, 5CG4, 6087, 5C4S
The 10P12S output pentode tube is designed to amplify low-frequency power in long-distance wired communication devices. Near equivalent: WE311A, 7P12S. Excellent sound!