27
Triode · IHT · UX-5 · 1927
“First indirectly heated triode. Ancestor of 6SN7.”
Low-mu triode with excellent linearity for driver and line stages
GAIN FACTOR0
PLATE IMPEDANCE0kΩ
TRANSCONDUCTANCE0mA/V
GAIN9%
POWER5%
DRIVE91%
LINEARITY95%
EXECUTIVE SUMMARY
The 27 is a indirectly-heated triode from RCA·GE, introduced around 1927. It provides a gain factor (μ) of 9 with 9000Ω plate resistance. Commonly used in preamp applications. First indirectly heated triode. Ancestor of 6SN7.
APPLICATIONS
Voltage amplifierLine stage
Generic triode preamp stage
• Hi-Fi stereo• Headphone amp
HISTORY
Introduced1927ManufacturerRCA·GEEquivalentsVT-29
Pre-WarSPECIFICATIONS
Heater Voltage2.5V
Heater Current1.75A
Max Plate Voltage250V
Max Power2W
Sensitivity1 mA/V
Gain Factor9
Internal Impedance9.0kΩ
PinoutUX-5
Era1927
RarityCollector
SPICE model not yet available. Loadline calculator requires calibrated Koren parameters.