CL33

High-sensitivity series-heater audio power pentode providing approximately 4 W Class A output in AC/DC receivers.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: -
Socket code: IO
Base pins: 8
Nominal heater: 33 V / 200 mA

Description

High-sensitivity power output pentode for AC/DC mains-operated receivers, with a typical 200 V operating point, 8 mA/V transconductance and 4 W output.

Socket description

International Octal

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: -
Socket code: IO
Base pins: 8
Nominal heater voltage: 33 V
Nominal heater current: 200 mA
Parallel heater voltage: -
Parallel heater current: -
Series capable: No

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: 35000 Ω
Transconductance: 0.008 S
Max plate voltage: 250 V
Max screen voltage: 250 V
Max plate dissipation: 9 W
Max screen dissipation: 2 W
Max cathode current: 70 mA

Pentode-connected Class A operating point 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

1951 Mullard Valve and Service Manual

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

Anode Voltage
200 V
ClassA
Screen Voltage
200 V
ClassA
Control Grid Voltage
-8.5 V
ClassA
Anode Current
45 mA
ClassA
Screen Current
6 mA
ClassA
Optimum Load
4500 ohm
ClassA
Power Output
4 W
ClassA
Power Output
0.7 W
ClassA; TriodeConnection

Data set 02

1963 Mullard

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

Anode voltage
200 V
Screen voltage
200 V
Control-grid voltage
-8.5 V
Anode current
45 mA
Screen current
6 mA
Load resistance
4500 ohm
Output power
4 W
Total distortion
10 %
Cathode resistor
167 ohm
Anode supply voltage maximum
400 V
Plate voltage maximum
250 V
Plate dissipation maximum
9 W
Cathode current maximum
70 mA
Screen supply voltage maximum
400 V
Screen voltage maximum
250 V
Screen dissipation maximum
2 W
Heater-cathode voltage maximum
175 V

Characteristic

Transconductance
8000 uS
Plate resistance
35000 ohm