EF53

Small Signal Pentode — Loctal

Philips

Known Equivalents & Substitutes

VR91A

Similar Tubes (Not Drop-In Compatible)

Earlier version (VR91) — same B9G base but inferior performance and higher noise; not all circuits will work with direct substitution

EF54

Similar B9G pentode with different operating point — verify characteristics before substituting

Functional successor on B7G miniature base — different pinout, not plug-compatible

Electrical Specifications

Absolute Maximum

Anode Voltage (max)Anode Voltage (max)300V

Screen Voltage (max)Screen Voltage (max)200V

Anode Dissipation (max)Anode Dissipation (max)2.5W

Screen Dissipation (max)Screen Dissipation (max)0.5W

Heater-to-Cathode Voltage (max)Heater-to-Cathode Voltage (max)

Heater

Heater VoltageHeater Voltage6.3V

Heater CurrentHeater Current0.2A

Notes

The EF53 is an improved version of the EF50 with higher gm and better noise performance.
B9G (Loctal) base has a central locating spigot and locking mechanism — requires the correct Loctal socket.
Pin 5 (metallising/shield) must be grounded for proper screening and lowest noise.
Widely used in British military radar equipment as VR91A during WWII.
Datasheet not available from frank.pocnet.net; specifications from Philips published data and cross-referenced with Brans Vademecum and valve equivalents references.

Pin Layout — Loctal

1Suppressor Grid (g3)

2Heater

3Anode