What is the UCL82 vacuum tube?

The UCL82 is a pentode vacuum tube designed for power applications.

What is a UCL82 substitute or equivalent?

Direct equivalents to the UCL82 include 50BM8. These share the same pinout and operating envelope, so they can usually be swapped without circuit changes — though batch-to-batch variations between manufacturers (NOS vs current production) may shift the sonic character noticeably.

Is the UCL82 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the UCL82 as Common availability. NOS (new-old-stock) examples from RCA, Mullard, Tung-Sol, GE, Sylvania and Telefunken trade among collectors; modern production where it exists comes mostly from JJ Electronic, Electro-Harmonix, Tung-Sol (New Sensor), Genalex, and a handful of small-batch makers.

What does the UCL82 sound like?

Sonic character depends on the circuit operating point, the surrounding tubes in the stage, and the output transformer when present. Use the interactive loadline calculator on this page to explore the trade-offs.

UCL82 Pentode Vacuum Tube

Also known as 50BM8

Triode + PentodeHeater 50 V · 0.1 A9-pin Noval2 sectionsPhilips·Mullard 1955

Triode · Plate dissipation: 1W
Triode · Amplification factor: 70
Pentode · Plate dissipation: 7W
Pentode · Max screen voltage: 250V

UCL82

Characteristics

Datasheet values, once each. Every value cites its sheet.

HeaterIndirectly heated

Specifications of UCL82 — Heater
Heater voltageVh	50 V
Heater currentIh	0.1 A

Mechanical

Specifications of UCL82 — Mechanical
Base	9-pin Noval
Rarity	Common
Pinout

TriodeTriode

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of UCL82-T — Triode — Limiting values
Plate voltageVa max	250 V
Screen voltageVg2 max	250 V
Plate dissipationPa max	1 W
Screen dissipationPg2 max	2 W
Cathode currentIk max	50 mA
Grid resistorRg1 max	1 MΩ
Peak plate voltageVao	550 V
Heater–cathode voltageVhk max	200 V

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of UCL82-T — Triode — Small signal
Transconductance	2.2 mA/V
Plate resistance	32 kΩ
Amplification factor	70

Capacitances

Specifications of UCL82-T — Triode — Capacitances
Grid–cathode	2.7 pF
Grid–plate	4.4 pF
Plate–cathode	4.3 pF

Charactereditorial reading, not a measurement

Specifications of UCL82-T — Triode — Character
Gain	70%
Power	3%
Drive	68%
Linearity	65%

PentodePentode

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of UCL82-P — Pentode — Limiting values
Plate voltageVa max	250 V
Screen voltageVg2 max	250 V
Plate dissipationPa max	7 W
Screen dissipationPg2 max	2 W
Cathode currentIk max	50 mA
Heater–cathode voltageVhk max	200 V

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of UCL82-P — Pentode — Small signal
Transconductance	7.5 mA/V
Plate resistance	16 kΩ
Amplification factor	10

Capacitances

Specifications of UCL82-P — Pentode — Capacitances
Input	9.3 pF
Grid–plate	0.3 pF
Output	8 pF

Charactereditorial reading, not a measurement

Specifications of UCL82-P — Pentode — Character
Gain	10%
Power	18%
Drive	84%
Linearity	95%

datasheet cited · model or editorial reading · catalogue value, no citation attached yet · nothing invented

Using this tube

Interactive loadline calculator not available for this tube yet — it needs calibrated Koren or Ayumi parameters.

Applications

Phase splitter

Generic pentode power stage

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Source : audit-eu_b (CLEAN — matches canonical datasheet)

Manufacturer datasheets

Triode

4 manufacturer datasheets cross-checked for UCL82 — Triode4 verified

Triode-connectedPhilips1969 (pages datées 1969.01 / 1969.12)

Va: 100 V
Vg1: 0 V
Ia: 3.5 mA
gm: 2.2 mA/V
µ: 16
Ra: 16 Ω

Pentode

4 manufacturer datasheets cross-checked for UCL82 — Pentode4 verified

Triode-connectedPhilips1969 (Dec 1969 / Jan 1969)

Va: 100 V
Vg1: 0 V
Ia: 3.5 mA
gm: 2.2 mA/V
µ: 16
Ra: 16 Ω

UCL82 DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: audit-eu_b (CLEAN — matches canonical datasheet)
Reviewed: 2026-05-29
Status: DataModelCalc
Model: under review

Context

The UCL82-T is a indirectly-heated triode from Philips·Mullard, introduced around 1955. It provides a gain factor (μ) of 70 with 32.0kΩ plate resistance. Commonly used in preamp applications. Triode section. The UCL82-P is a indirectly-heated pentode from Philips·Mullard, introduced around 1955. It provides a gain factor (μ) of 10 with 16.0kΩ plate resistance. Commonly used in power applications. Pentode section. 100mA series heater.

History

Introduced: 1955
Manufacturer: Philips·Mullard
Era: Golden Age

METRIX TESTER

Characteristics

HeaterIndirectly heated

Mechanical

TriodeTriode

Limiting valuesDatasheet maximum ratings — not to be exceeded

Small signalDatasheet parameters at the reference operating point — not limits

Capacitances

Charactereditorial reading, not a measurement?

PentodePentode

Limiting valuesDatasheet maximum ratings — not to be exceeded

Small signalDatasheet parameters at the reference operating point — not limits

Capacitances

Charactereditorial reading, not a measurement?

Using this tube

Applications

Replace or compare

Versus 12SJ7

Similar tubes

Sources

Manufacturer datasheets

SPICE models

Context

History

Test this tube on a Metrix

Charactereditorial reading, not a measurement

Charactereditorial reading, not a measurement