KT150 — Beam Tetrode, Octal | Tubeofile

KT150

Beam Tetrode — Octal

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Tung-Sol

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Known Equivalents & Substitutes

No known equivalents. If you know of any, use the ⚑ Report Issue button above.

Similar Tubes (Not Drop-In Compatible)

KT120

Same Tung-Sol octal beam tetrode family with similar pin functions. KT150 has higher Pa_max (70W vs 60W) and higher heater current (1.75-2.0A vs 1.65A). Requires verification of heater supply capacity.

KT88

Same Octal base beam tetrode family but KT150 has much higher ratings (Pa_max 70W vs 42W) and higher heater current. Not a drop-in — requires circuit redesign.

Electrical Specifications

Absolute Maximum

Anode Voltage (max)Anode Voltage (max, tetrode)850V

Screen Voltage (max)Screen Voltage (max, pentode)650V

Anode Dissipation (max)Anode Dissipation (max)70W

Screen Dissipation (max)Screen Dissipation (max)9W

Cathode Current (max)Cathode Current (max, pentode)275mA

Typical Operating

Anode Voltage (typical)Anode Voltage400V

Screen Voltage (typical)Screen Voltage225V

Grid 1 Bias VoltageGrid 1 Bias Voltage-14V

Anode CurrentAnode Current150mA

Screen CurrentScreen Current

Output

Output PowerOutput Power20W

Load ImpedanceLoad Impedance3,000Ω

Capacitances

Grid-to-Plate CapacitanceGrid 1 to Plate Capacitance1.75pF

Input CapacitanceInput Capacitance20.5pF

Output CapacitanceOutput Capacitance10pF

Heater

Heater VoltageHeater Voltage6.3V

Heater CurrentHeater Current1.75A

Notes

Rg_max depends on bias method: fixed bias 51 kΩ, self (cathode) bias 240 kΩ.
Maximum ratings differ between tetrode and triode/UL modes: Va_max tetrode = 850 V, Va_max triode = 650 V; Vg2_max pentode = 650 V, Vg2_max triode/UL = 600 V; Ik_max pentode = 275 mA, Ik_max triode/UL = 250 mA.
Pin 1 is the outer metal screen (internal shield), not a beam plate connection. Pin 8 is cathode tied to the beam-forming plates internally.
The KT150 is physically larger than a KT88 or KT120 (60 mm diameter, 140 mm seated height, 130 g) — verify clearance and heater current capacity before substitution.
Heater current is 1.75–2.0 A (higher than KT88/6550) — confirm power transformer heater winding rating before use.
Tube impedance range is 10.0–12.5 kΩ (per TAD datasheet).
The Tung-Sol datasheet provides triode/UL maximum ratings but no triode-strapped operating point or small-signal parameters.

Pin Layout — Octal

1Outer Metal Screen (internal shield)

2Heater

3Anode (Plate)

Socket-Compatible Tubes ⚠ Not electrically compatible

6L6 KT120 KT170 KT63

References