6S4A

Name: 6S4A
Brand: Tung-Sol

Small Signal Triode — Noval — Tung-Sol

Data: HighHigh quality — base, heater, all universal parameters present, and ≥50% of desirable parameters filled in. Safe to use for design decisions.

↗ TDSL ↗ Radiomuseum

Known Equivalents & Substitutes

6S4

Electrical Specifications

Absolute Maximum

Anode Voltage (max)DC Plate Voltage (max)550V

Peak Anode Voltage (max)Peak Positive Plate Voltage (abs max)2,200V

Anode Dissipation (max)Plate Dissipation (max)8.5W

Cathode Current (max)Average Cathode Current (max)30mA

Notes

6S4A is identical to 6S4 electrically; only heater thermal characteristics differ (controlled warm-up time). TDSL lists 6S4 as a 'different rating or performance' substitute.
Base is Small-Button Noval 9-Pin (JEDEC No. E9-1), basing designation 9AC. Pins 1, 7, and 8 are internal connections — do not use.
Philips interchange guide lists 6S4 -> 6S4A and 6S4A -> 6S4A (self-replacement).
MIL-HDBK-213A classifies as 'Receiving triode, miniature' and cross-references 6S4A as an other number for 6S4.
Brans Vademecum table IIIf lists 6S4 with equivalents 6BJ8 and 7AU7.
GE Essential Characteristics lists a max plate dissipation of 7.5 W for the 6S4; the Tung-Sol and RCA datasheets for 6S4A specify 8.5 W. The datasheet value of 8.5 W is used here.
The peak positive plate voltage rating of 2200 V reflects vertical-deflection service where flyback pulses are present.
Heater warm-up time is 11 seconds (defined as time to reach 80% of rated voltage across heater in a specified test circuit).

Pin Layout — Noval

1Internal Connection

2Cathode

3Grid

Socket-Compatible Tubes ⚠ Not electrically compatible

6203 AL860

References