What is the 7868 vacuum tube?

The 7868 is a pentode vacuum tube designed for power (pp) applications. Similar to 7591..

What is a 7868 substitute or equivalent?

Direct equivalents to the 7868 include 7591. 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 7868?

Transconductance gm ≈ 10.2 mA/V, plate resistance rp ≈ 29.0 kΩ, max plate voltage 550 V, max plate dissipation 19 W, heater 6.3 V / 0.8 A.

Is the 7868 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 7868 as Sought-after 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 7868 sound like?

Similar to 7591.. 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.

7868 Pentode Vacuum Tube

Also known as 7591

Power pentode delivering up to 19W in pentode, UL, or triode mode

PentodeHeater 6.3 V · 0.8 A9-pin NovalGE·Sylvania 1960

Plate dissipation: 19W
Max plate voltage: 550V
Transconductance: 10.2mA/V

7868

Characteristics

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

HeaterIndirectly heated

Specifications of 7868 — Heater
Heater voltageVh	6.3 V
Heater currentIh	0.8 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of 7868 — Limiting values
Plate voltageVa max	550 V
Plate dissipationPa max	19 W

Mechanical

Specifications of 7868 — Mechanical
Base	9-pin Noval
Rarity	Sought-after
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of 7868 — Small signal
Transconductance	10.2 mA/V
Plate resistance	29 kΩ

Capacitances

Specifications of 7868 — Capacitances
Input	11 pF
Grid–plate	0.15 pF
Output	4.4 pF

Charactereditorial reading, not a measurement

Specifications of 7868 — Character
Gain	0%
Power	48%
Drive	71%
Linearity	75%

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

Typical operation

Conditions published by the manufacturers, one row per condition. Nothing is computed.

Typical operation
Setup	Va	Vg2	Vg1 / Rk	Ia	Load	Pout	THD	gm	Source
Class A, single-endedpentode connection · fixed bias	300 V	300 V	-10 V	60 mA	3 kΩ	11 W	13%	10.2 mA/V	OCR, to be checked RCA · 1961 · p. 9 · transcript

Using this tube

Applications

Power output

Generic pentode power (pp) stage

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Active model : Koren pentode

Manufacturer datasheets

2 manufacturer datasheets cross-checked for 78682 verified

7868 DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: GE·Sylvania
Reviewed: 2026-05-29
Status: DataModelCalc
Model: Koren pentode

Context

The 7868 is a indirectly-heated pentode from GE·Sylvania, introduced around 1960. Commonly used in power (pp) applications. Similar to 7591.

History

Introduced: 1960
Manufacturer: GE·Sylvania
Era: Late Production

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