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6AC7 and 6AC7GT Vacuum Tube New and Used

- Description
- Specifications
The 6AC7 and 6AC7GT are octal-base sharp-cutoff pentodes engineered for wideband video amplifier, radar IF, and high-frequency RF applications requiring exceptionally high transconductance ($9,000\text{ }\mu\text{mhos}$).
6AC7: Features a standard drawn-steel metal envelope. Pin 1 grounds the metal shell directly to the chassis, providing optimal RF shielding for high-gain wideband circuits in early television sets, radar displays, and communications receivers.
6AC7GT: Features a glass T-9 tubular envelope with a tubular glass construction. Produced primarily during wartime material shortages or by specialized manufacturers, it requires an external metallic tube shield when used in sensitive RF or video stages to prevent oscillation.
Both versions operate on a 6.3V/0.45A heater and share identical electrical parameters and pinouts. Widely specified in chassis produced by RCA Victor, Zenith, Philco, and General Electric. Available in NOS and tested used conditions.
Type: High-Transconductance Sharp-Cutoff Pentode (Wideband RF/Video Amplifier)
Base: 8-Pin Octal (EIA 8N layout — Pin 1 Shell/Shield Ground)
Construction Variants:
6AC7: Metal Envelope (Internal shielding via Pin 1)
6AC7GT: Tubular Glass T-9 Envelope (Requires external shield in RF/Video stages)
Heater Voltage: 6.3V
Heater Current: 0.45A (450 mA)
Max Plate Voltage: 300V
Max Screen Grid Voltage (Grid 2): 150V (Fixed) / 300V (Series Resistor)
Max Plate Dissipation: 3.0W
Transconductance ($g_m$): $9,000text{ }mutext{mhos}$ ($9.0text{ mA/V}$)
Equivalents & Relatives: 6AC7, 6AC7GT, 1852 (commercial designation), VT-112 (military designation), 6AC7Y, 6Ж4 (Soviet equivalent)