205D

Triode · DHT · UX-4 · 1930

WE transmitting triode.

Power triode delivering 14W for push-pull and SET designs

Datasheet ↗SPICE
GAIN FACTOR0
PLATE IMPEDANCE0kΩ
TRANSCONDUCTANCE0mA/V
GAIN6%
POWER35%
DRIVE97%
LINEARITY95%
HEATER4.5V / 1.1A
MAX PLATE425V / 14W
BASEux4
TYPICAL OPERATING POINT
Va400V
Ia35.16mA
Vg-27V
Pd14.06W
RL5kΩ
Av12.7dB
EXECUTIVE SUMMARY

The 205D is a Western Electric directly-heated triode from the 1930s, closely related to the 300B but with lower power output (around 4-5W in single-ended Class A). It represents an earlier stage in the WE power triode development lineage and is considered by some to have an even more refined midrange than the 300B, with less bass weight but greater delicacy. Like the 101D, it exists in a rarefied collector market where provenance and condition are paramount. Modern reproductions exist from boutique manufacturers, but the tube remains a niche pursuit even within the already specialized DHT community.

APPLICATIONS
SET outputPush-pull output
Generic triode power (set) stage
Hi-Fi stereo
HISTORY
Introduced1930ManufacturerWestern ElectricEquivalentsNone
Pre-War
SPECIFICATIONS
Heater Voltage4.5V
Heater Current1.1A
Max Plate Voltage425V
Max Power14W
Sensitivity1.8 mA/V
Gain Factor6
Internal Impedance3.3kΩ
PinoutUX-4
Era1930
RarityLegendary
PDF

205D Datasheet

Frank's Electron Tube Pages · PDF