47
Pentode · DHT · UX-5 · 1931
“Earliest power pentode. Pre-octal era output.”
Small-signal pentode for low-noise voltage amplification
TRANSCONDUCTANCE0mA/V
GAIN0%
POWER8%
DRIVE50%
LINEARITY75%
EXECUTIVE SUMMARY
The 47 is a directly-heated pentode from RCA·Sylvania, introduced around 1931. Commonly used in power/output applications. Earliest power pentode. Pre-octal era output.
APPLICATIONS
Voltage amplifier
Generic pentode power/output stage
HISTORY
Introduced1931ManufacturerRCA·SylvaniaEquivalentsVT-47, 247
Pre-WarSPECIFICATIONS
Heater Voltage2.5V
Heater Current1.75A
Max Plate Voltage250V
Max Power3.1W
Sensitivity2.5 mA/V
Gain Factor—
Internal Impedance—
PinoutUX-5
Era1931
RaritySought-after
SPICE model not yet available. Loadline calculator requires calibrated Koren parameters.