Vacuum Tube - 78, Pentode, Remote Cut-Off
New-Old-Stock (NOS) tube.
Also known by US military identifier VT-78.
The 78 is a heater-cathode type pentode amplifier tube with remote cut-off characteristics and is designed for use as a radio frequency or intermediate frequency amplifier in a-c or battery operated equipment. Except for capacitances the electrical ratings and characteristics of the 78 are identical with those of types 6K7, 6K7G, and 6K7GT.