High-Mu Triode
See 4HA5. It is the exact same tube as a PC900.
The 4HA5 Vacuum tube is a miniature type used as an
RF-amplifier tube in VHF TV tuners. It requires a
miniature 7-contact socket.
Electrical Data:
Heater Voltage ................................ 3.9 V
Heater Current ................................ 0.3 A
Preferred Substitutes ........... 4HK5, 4HQ5, PC900