Sharp-Cutoff Tetrode
These are commonly called Balloon or Globe types.
The Globe 224 Vacuum tube is a glass type
used as an RF amplifier or biased detector
in AC-operated receivers. It was first developed in 1930
by RCA and requires a five-contact socket.
Electrical Data:
Filament Voltage .............................. 2.5 V
Filament Current .............................. 1.75 A
Preferred Substitutes ................... 24, 24A,
35, 51, 224A, 324, 324A, CX-324A, NY-224, NY224,
TS-224, TS224, UX-224A