Sensibly equivalent¶ to:
The TH41 is a triode heptode mixer for mains receivers. The data-sheet says that it was specifically designed for 'all-wave' receivers ie including short wave up to 30 MHz.
It uses the UK pre-war standard 4.0 Volt heater but draws 1.3 Amps.
The pin-out matches that of the the universal TH233 but the mutual conductance is much higher.
Where the zinc paint has come away from the glass the internal structure is visible. Above the bottom mica is the small diameter bright cylinder of the triode anode and a circular grid is just visible within. The adhesive makes identification difficult but the cathode looks to be cylindrical. The heptode is above and the anode is blackened. The cathode for this part is a wide flat rectangle.
The classic envelope is 32 mm in diameter, and excluding the MO base pins is 99 mm tall.
References: Datasheet, 1040 & 1043. Type TH41 was first introduced in 1939.
Absolute Maximum Operating Conditions¶
Updated January 14, 2017. shape:classic construction:pinch type:triode.heptode age:1930.1940 base:mo heater:4.0v pins:8 pin:1.h pin:2.k pin:3.a pin:4.a(t) pin:5.g1(t).g3 pin:6.m pin:7.g2.g4 pin:8.h pin:tc.g1