What is the 35LR6 vacuum tube?

The 35LR6 is a pentode vacuum tube designed for sweep / power applications. High-power sweep tube. 35V heater chain..

What is a 35LR6 substitute or equivalent?

Direct equivalents to the 35LR6 include 6LR6 (35V heater). 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.

What are the key specifications of the 35LR6?

Transconductance gm ≈ 16 mA/V, max plate voltage 900 V, max plate dissipation 30 W, heater 35 V / 0.6 A.

Is the 35LR6 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 35LR6 as Moderate 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 35LR6 sound like?

High-power sweep tube. 35V heater chain.. Sonic character also depends heavily 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.

35LR6 Pentode Vacuum Tube

Also known as 6LR6 (35V heater)

Power pentode delivering up to 30W in pentode, UL, or triode mode

PentodeHeater 35 V · 0.6 A12-pin CompactronSylvania·RCA 1968

Plate dissipation: 30W
Max plate voltage: 900V
Transconductance: 16mA/V

35LR6

Characteristics

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

HeaterIndirectly heated

Specifications of 35LR6 — Heater
Heater voltageVh	35 V
Heater currentIh	0.6 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of 35LR6 — Limiting values
Plate voltageVa max	900 V
Plate dissipationPa max	30 W

Mechanical

Specifications of 35LR6 — Mechanical
Base	12-pin Compactron
Rarity	Moderate
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of 35LR6 — Small signal
Transconductance	16 mA/V

Capacitances

Specifications of 35LR6 — Capacitances
Input	17 pF
Grid–plate	1 pF
Output	12 pF

Charactereditorial reading, not a measurement

Specifications of 35LR6 — Character
Gain	0%
Power	75%
Drive	50%
Linearity	75%

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

Power output

Generic pentode sweep / power stage

PA/public address

Replace or compare

Sources

By Jean-Michel Falligan Devergne

Manufacturer datasheets

35LR6 DatasheetFrank's Electron Tube Pages · PDF

SPICE models

Revision and verification status

Source: Sylvania·RCA
Reviewed: —
Status: DataModelCalc
Model: under review

Context

The 35LR6 is a indirectly-heated pentode from Sylvania·RCA, introduced around 1968. Commonly used in sweep / power applications. High-power sweep tube. 35V heater chain.

History

Introduced: 1968
Manufacturer: Sylvania·RCA
Era: Late Production

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