3Z4

3Z4 directly heated low-power audio-output pentode for battery receivers, with 1.4 V parallel or 2.8 V series filament operation.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: -
Socket code: -
Base pins: 7
Nominal heater: 1.4 V / 50 mA

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: -
Socket code: -
Base pins: 7
Nominal heater voltage: 1.4 V
Nominal heater current: 50 mA
Parallel heater voltage: 1.4 V
Parallel heater current: 50 mA
Series capable: Yes

Terminal pinout

Electrical assignments shared by every tube using this base designation.

No verified pinout is recorded for this base designation.

Section ratings

1 physical section, each with unique specifications.

Section 1

Pentode

X-ray radiationInterelectrode capacitances

Plate resistance: 100000 Ω
Transconductance: 0.00145 S
Max plate voltage: 90 V
Max screen voltage: 67.5 V
Max cathode current: 11 mA

3Z4 RETMA/JETEC low-power audio pentode. Typical plate 67.5 V, grid 1 -7 V, zero-signal plate current 6.5 mA, screen current 1.3 mA, load 2000 ohms, 0.21 W audio output, 12% THD. Typical screen voltage OCR ambiguous; no unverified value promoted.

Source-dependent data

Operating conditions by source

Each block preserves the test conditions and published values from one reference. Values from different sources are intentionally kept separate.

Data set 01

9999 Mixed 2000

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

Plate voltage
67.5 V
Typical plate voltage
Control-grid voltage
-7 V
Typical grid 1 voltage
Plate current
6.5 mA
Zero-signal plate current
Screen current
1.3 mA
Zero-signal screen current

Characteristic

Plate resistance
100000 Ω
Approximate plate resistance
Transconductance
1450 µS
Transconductance