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Power - Pentode (NOT beam) ·Pentode

PT25H

High-efficiency Marconi power pentode for substantial Class A audio output.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
-
Socket code
-
Base pins
-
Nominal heater
4 V / 2 A

Description

The PT25H is a high-efficiency power pentode capable of substantial class-A audio output.

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
-
Socket code
-
Base pins
-
Nominal heater voltage
4 V
Nominal heater current
2 A
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

No fixed ratings are recorded for this section.

Published maximum ratings and characteristics audited; remaining useful numerical data retained in parameter table.

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

1955 Marconi

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

  • Published value [1]

    2 A

    2‘\ FILAMENT CURRENT 2-0 AMPS.

  • Published value [2]

    2 A

    2‘\ FILAMENT CURRENT 2-0 AMPS.

  • Published value [3]

    0 mA

    2‘\ FILAMENT CURRENT 2-0 AMPS.

  • ANODE VOLTS S0

    0

    ANODE VOLTS S00MAX. .

  • Ar £ [1]

    4100 ohm

    Ar £4100. £6O Marconi PX25 is a low impedance

  • Ar £ [2]

    6 ohm

    Ar £4100. £6O Marconi PX25 is a low impedance

  • Ar £ [3]

    5 ohm

    Ar £4100. £6O Marconi PX25 is a low impedance

  • < J| ‘_’"{;,‘,‘ffif,‘,’,‘,’?,”,‘fi:”””' triode giving }bout

    5

    < J| ‘_’"{;,‘,‘ffif,‘,’,‘,’?,”,‘fi:”””' triode giving }bout 5 watts output in

  • A ] T H [1]

    4000 ohm

    A ] T H 4000 ohms, bias resistance 475 ohms,

  • A ] T H [2]

    475 ohm

    A ] T H 4000 ohms, bias resistance 475 ohms,

  • Published value [1]

    1

    1 7 T grid bias 30 volts.

  • Published value [2]

    7

    1 7 T grid bias 30 volts.

  • Published value [3]

    30

    1 7 T grid bias 30 volts.

  • VRN = il AULANENT CURRENT [1]

    20 A

    : VRN = il AULANENT CURRENT 20of | efficiency pentode giving 10

  • VRN = il AULANENT CURRENT [2]

    10 A

    : VRN = il AULANENT CURRENT 20of | efficiency pentode giving 10

  • S grid bias of only

    16

    S grid bias of only 16 volts,

  • bias resistance

    240 ohm

    bias resistance 240 ohms,

  • screen current

    12.5 mA

    screen current 12.5 mA,