71A
Triode · DHT · UX-4 · 1926
“Sub-watt SET. Intimate, delicate.”
Low-mu triode with excellent linearity for driver and line stages
GAIN FACTOR0
PLATE IMPEDANCE0kΩ
TRANSCONDUCTANCE0mA/V
Cgk0pF
Cgp0pF
Cpk0pF
GAIN3%
POWER10%
DRIVE98%
LINEARITY95%
EXECUTIVE SUMMARY
The 71A is a directly-heated triode from RCA·Sylvania, introduced around 1926. It provides a gain factor (μ) of 3 with 1850Ω plate resistance. Commonly used in power (set) applications. Sub-watt SET. Intimate, delicate.
APPLICATIONS
Headphone outputLine stage
Generic triode power (set) stage
• Hi-Fi stereo• Headphone amp
HISTORY
Introduced1926ManufacturerRCA·SylvaniaEquivalents171A, VT-71A
Pre-WarSPECIFICATIONS
Heater Voltage5V
Heater Current0.25A
Max Plate Voltage180V
Max Power4W
Sensitivity1.6 mA/V
Gain Factor3
Internal Impedance1.9kΩ
PinoutUX-4
Era1926
RarityCollector
Input Capacitance3.7pF
Miller Capacitance2.1pF
Output Capacitance7.4pF
SPICE model not yet available. Loadline calculator requires calibrated Koren parameters.