6528 — Power Triode, Octal | Tubeofile

6528

Power Triode — Octal

Tung-Sol

Known Equivalents & Substitutes

CV9094

Similar Tubes (Not Drop-In Compatible)

Same pinout but much lower current capability (125 mA/plate vs 300 mA/plate) and lower gm

6336

Same pinout but much lower mu and gm

6336A

Same pinout but much lower mu (2.7 vs 9.0) and gm (13,500 vs 37,000 umhos)

Same pinout but much lower mu (2.7 vs 9.0) and gm (13,500 vs 37,000 umhos)

6AS7G

Same pinout but much lower current capability (125 mA/plate vs 300 mA/plate) and lower gm

Electrical Specifications

Absolute Maximum

Anode Voltage (max)Plate Voltage (max)400V

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

Heater-to-Cathode Voltage (max)Heater-Cathode Voltage (max)300V

Max Grid ResistorGrid Circuit Resistance (max, fixed bias)50,000MΩ

Typical Operating

Notes

Designed exclusively as a series pass tube for voltage regulators, not as an audio output tube. No load impedance or output power data is published — regulator service does not use a conventional load line.
One 6528 replaces two or three 6080WA or three or four beam power tubes in regulator circuits.
When sections are paralleled, minimum cathode resistance per cathode leg shall be 10 ohms or the resistance necessary to provide 10% of the grid bias voltage, whichever is greater.
A grid resistor of 1,000 ohms is recommended per triode section to prevent parasitic oscillation while remaining low enough to avoid loss of control from gas current.
A 30-second cathode warmup time is recommended before plate voltage is applied. This is critical in circuits where the amplifier tube plate resistor is returned to the plate side of the passing tube — during warmup the grid is effectively tied to the plate and may draw excessive current.
Heater draws 5.0 A at 6.3 V (31.5 W) — requires a dedicated or heavy-duty heater supply. When connecting many high-drain tube heaters across a single transformer, use bus bars feeding from alternate ends with a stranded pair feeding individual sockets.
Plate current per plate cannot exceed 300 mA if tube voltage drop is to be swung more than 6 volts.
Data marked 'Tentative Data' on the Tung-Sol datasheet (April 1958) — the tube was registered with RETMA in September 1957.

Pin Layout — Octal

1Grid (Section 2)

2Plate (Section 2)

3Cathode (Section 2)

Socket-Compatible Tubes ⚠ Not electrically compatible

References