6AC7

Small Signal Pentode — Octal

Tung-Sol

Known Equivalents & Substitutes

18526AC7ACV660CV747CV846CV849

Similar Tubes (Not Drop-In Compatible)

Similar sharp-cutoff pentode but B7G base — not pin-compatible

Soviet 6J4 (6Ж4) listed as equivalent — check pinout compatibility

Similar sharp-cutoff pentode on Octal base but lower gm (1650 vs 9000 umhos)

Electrical Specifications

Absolute Maximum

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

Screen Voltage (max)Screen Voltage (max)150V

Anode Dissipation (max)Anode Dissipation (max)3W

Screen Dissipation (max)Screen Dissipation (max)0.38W

Heater-to-Cathode Voltage (max)

Notes

The 6AC7/1852 features exceptionally high transconductance (9000 umhos) with only 10mA plate current, making it ideal for high-gain RF and IF stages.
Two operating conditions: Condition 1 (fixed screen supply, sharp cutoff) and Condition 2 (series screen resistor 60kΩ, extended cutoff for AGC applications).
Metal shell with internal shield connected to pin 1. Suppressor (grid 3) should be connected to ground to minimize feedback.

Pin Layout — Octal

1Shell (Internal Shield)

2Heater

3Anode

4

Socket-Compatible Tubes ⚠ Not electrically compatible

References