25A6

Max, Plate Voltage

180 V

Published ratings

Max, Screen Voltage

135 V

Published ratings

Plate Voltage

95 V

ClassA; Column1

Plate Voltage

135 V

ClassA; Column2

Plate Voltage

180 V

ClassA; Column3

Screen Voltage

95 V

ClassA; Column1

Screen Voltage

135 V

ClassA; Column2

Screen Voltage

135 V

ClassA; Column3

r‘an §V Grid Bias

-15 V

ClassA; Column1

r‘an §V Grid Bias

-20 V

ClassA; Column2

r‘an §V Grid Bias

-20 V

ClassA; Column3

MAK *k Amplification Factor (approxy

90

ClassA; Column1

MAK *k Amplification Factor (approxy

85

ClassA; Column2

MAK *k Amplification Factor (approxy

100

ClassA; Column3

e Plate Resistance {approx

45000

ClassA; Column1

e Plate Resistance {approx

35000

ClassA; Column2

e Plate Resistance {approx

40000

ClassA; Column3

Plate Current

20 mA

ClassA; Column1

Plate Current

37 mA

ClassA; Column2

Plate Current

38 mA

ClassA; Column3

PR L Load Resistance

4500 ohm

ClassA; Column1

PR L Load Resistance

4000 ohm

ClassA; Column2

PR L Load Resistance

5000 ohm

ClassA; Column3

Total Harmonic Distortion

11 %

ClassA; Column1

Total Harmonic Distortion

9 %

ClassA; Column2

Total Harmonic Distortion

10 %

ClassA; Column3

Dw[] *l\N' Power Output

0.9 W

ClassA; Column1

Dw[] *l\N' Power Output

2 W

ClassA; Column2

Dw[] *l\N' Power Output

2.75 W

ClassA; Column3

Heater to cathode bies should not exceed

90

ClassA

The

25

The 25A6 is a power-amplifier

HEATER VOLTAGE (A. C.or D. C)......oiiin.t,

25 V

HEATER VOLTAGE (A. C.or D. C)......oiiin.t, 25 Volts

HEATER CURRENT tvtivenenasnconrnnnsonnonnnns

300 mA

HEATER CURRENT tvtivenenasnconrnnnsonnonnnns 0.3 Ampere

PLATE VOLTAGE .. .cuvviuennennnnn

180 V

PLATE VOLTAGE .. .cuvviuennennnnn 95 135 180 max. Volts

ScrREEN VoLTAaGE (Grid No

135 V

ScrREEN VoLTAaGE (Grid No. 2)..... 95 135 135 max. Volts

Grip VoLTAGE (Grid No

20 V

Grip VoLTAGE (Grid No. 1)........ -15 =20 =20 Volts

PLATE CURRENT ..vtvrecnvenacnn

38

PLATE CURRENT ..vtvrecnvenacnn. 20 37 38 Milliamperes

SCREEN CURRENT .. vvvvvnnnnnnnn

7.5

SCREEN CURRENT .. vvvvvnnnnnnnn 4 8 7.5 Milliamperes

AMPLIFICATION FACTOR (Approx.)

100

AMPLIFICATION FACTOR (Approx.)... 90 85 100

SELF-BIAS RESISTOR

440 ohm

SELF-BIAS RESISTOR ............... 625 440 440 Ohms

POWER OUTPUT ....vovvunnennnn

2.75 W

POWER OUTPUT ....vovvunnennnn.. 0.9% 27 2.75% Watts

The

25 V

The 25-volt heater of the 25A6 is designed to operate under the normal

other types having

300 mA

other types having 0.3-ampere rating, the current in the heater circuit should be

adjusted to

300 mA

adjusted to 0.3 ampere for the normal supply voltage.

0.3-ampere (6.3-volt) types and one or two 25A6’s, the heate

25 A

0.3-ampere (6.3-volt) types and one or two 25A6’s, the heaters of the 25A6's

cathode voltage of the

25

cathode voltage of the 25A6 must not exceed the value given under cathode.

or two

6.3 A

or two 25A6’s, and several 0.3-ampere (6.3-volt) types, it is recommended that the

heater-cathode bias will be impressed on the

6.3 V

heater-cathode bias will be impressed on the 25A6(’'s) rather than on the 6.3-volt

the rectified voltage supply. Between this side of the line and the

25

the rectified voltage supply. Between this side of the line and the 25A6(’s), any

of the

90 V

of the 25A6 should not exceed 90 volts d.c., as measured between the negative

As a power amplifier (Class A), the

25

As a power amplifier (Class A), the 25A6 is recommended for use either singly

self-bias; or

135 V

self-bias; or 0.5 megohm for the 95-volt condition and 50000 ohms for the 135-volt

and

180 V

and 180-volt conditions with fixed bias.

E£=

25 V

E£=25 VOLTS

SCREEN VOLTS =

43 V

SCREEN VOLTS =43§

z ,//" N ™~

-2

z ,//" N ™~ -2°

PLATE VOLTS

4559 V

PLATE VOLTS 92C-4559

325 VOLTS

325 V

325 VOLTS

|~ Escreen voLTs =

110 V

|~ Escreen voLTs =110 fi

PLATE RESISTANCE (Approximate)

40000 ohm

PLATE RESISTANCE (Approximate)... 45000 35000 40000 Ohms

TRANSCONDUCTANCE ........cc

2500 µS

TRANSCONDUCTANCE ........cc.... 2000 2450 2500 Micromhos

Loap RESISTANCE

5000 ohm

Loap RESISTANCE ................ 4500 4000 5000 Ohms

The total d-c resistance in the grid circuit should not exceed

0.5

The total d-c resistance in the grid circuit should not exceed 0.5 megohm with

Service

Audio power output

Input capacitance

8.5 pF

Output capacitance

12.5 pF

Grid-to-plate capacitance

0.2 pF

Plate resistance

42000 ohm

ClassA; OperatingPoint1

Transconductance

2375 uS

ClassA; OperatingPoint1

Plate voltage

160 V

ClassA; OperatingPoint1

Screen voltage

120 V

ClassA; OperatingPoint1

Control-grid bias

18 V

ClassA; OperatingPoint1

Plate current

33 mA

ClassA; OperatingPoint1

Screen current

6.5 mA

ClassA; OperatingPoint1

Load resistance

5000 ohm

ClassA; OperatingPoint1

Power output

2.2 W

ClassA; OperatingPoint1

Maximum plate voltage

160 V

Maximum screen voltage

135 V

Plate Voltage

160 V

ClassA

Screen Voltage

120 V

ClassA

Power Output

2.2 W

ClassA

Load Resistance

5000 ohm

ClassA