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.

By Jean-Michel Falligan Devergne · Reviewed May 29, 2026

UCL82 Pentode Vacuum Tube

Triode + Pentode50 V · 0.1 A9-pin Noval2 sectionsAlso known as50BM8

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

UCL82

In brief

TriodeTriode

μ: 70
gm: 2.2 mA/V
rp: 32 kΩ
Pa: 1 W

PentodePentode

μ: 10
gm: 7.5 mA/V
rp: 16 kΩ
Pa: 7 W

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.

Limits

Specifications of UCL82
Specification	Value	Source
Heater
Heater voltage	50 V	Datasheet
Heater current	0.1 A	Datasheet

Specifications of UCL82-T — Triode
Specification	Value	Source
LimitsDatasheet maximum ratings — not to be exceeded
Max Plate V	250 V	Datasheet
Pa max	1 W	Datasheet

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

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

HISTORY

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

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