Ampera
NR47
Triode · DHT · UX-4 · 1940
“European DHT.”
High-power directly-heated triode for single-ended amplification
Datasheet ↗SPICE
GAIN FACTOR0
PLATE IMPEDANCE0kΩ
TRANSCONDUCTANCE0mA/V
Cgk0pF
Cgp0pF
Cpk0pF
GAIN5%
POWER63%
DRIVE99%
LINEARITY95%
TYPICAL OPERATING POINT
EXECUTIVE SUMMARY
The NR47 is a directly-heated triode from Various, introduced around 1940. It provides a gain factor (μ) of 4.5 with 1500Ω plate resistance. Commonly used in power applications. European DHT.
APPLICATIONS
SET outputPush-pull outputHeadphone output
Generic triode power stage
• Hi-Fi stereo• Headphone amp
HISTORY
Introduced1940ManufacturerVariousEquivalentsPX25 class
Pre-WarSPECIFICATIONS
Heater Voltage4V
Heater Current2A
Max Plate Voltage400V
Max Power25W
Sensitivity3 mA/V
Gain Factor4.5
Internal Impedance1.5kΩ
PinoutUX-4
Era1940
RarityRare
Input Capacitance5pF
Miller Capacitance8pF
Output Capacitance4pF