6L6GC — Beam Tetrode, Octal | Tubeofile

6L6GC

Beam Tetrode — Octal

RCA

Known Equivalents & Substitutes

6L66L6G6L6GA6L6GB6L6WGB6P3S6P3S-E6N3CCV1947

Similar Tubes (Not Drop-In Compatible)

Same pinout but significantly lower max ratings (400V/23W vs 500V/30W) — not safe as drop-in at GC operating limits

Same 6L6 family with same pinout but higher plate and screen voltage ratings (600V vs 500V)

Tung-Sol direct replacement for 6L6GC with improved zero-bias characteristics and low-loss base

Sams lists as substitute — Mullard Octal power pentode with similar characteristics but different internal design

Sams lists as mutual substitute — GEC beam tetrode with similar characteristics but different internal construction

Electrical Specifications

Section 1 — Beam Tetrode

Absolute Maximum

Anode Voltage (max)Plate Voltage (max)500V

Screen Voltage (max)Screen Voltage (max)450V

Anode Dissipation (max)Plate Dissipation (max)30W

Screen Dissipation (max)Screen Dissipation (max)5W

Notes

Data from RCA datasheet dated 8-60. The 6L6GC has substantially higher ratings than the original 6L6: Pa_max 30W vs 19W, Va_max 500V vs 360V, Vs_max 450V vs 270V, Ps_max 5W vs 2.5W.
Pin 1 is not connected on 6-pin base variants; on medium-shell Octal bases pin 1 may connect to an internal shield. Pin 6 has no connection on any variant.
Rg_max of 0.1 MΩ applies to fixed-bias operation. For cathode-bias (self-bias) circuits, up to 0.5 MΩ is permitted.
Triode-strapped data from RCA datasheet page 3 (triode connection, grid No.2 connected to plate). Schlangen (2009) corroborates mu=8, gm=4.7 mA/V, ra=1700 Ω for the 6L6 family.
MIL-HDBK-213A classifies the 6L6GC as a beam power amplifier. Brans Vademecum cross-lists 6L6GC(WGB) with the 6L6 family.
Sams lists KT66 as substitute for 6L6GC, and 6L6GC as substitute for KT66 and DL37.

Pin Layout — Octal

1No Connection

2Heater

3Plate

Socket-Compatible Tubes ⚠ Not electrically compatible

References