NJ7P SQL Tube Database Query

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47
Power Pentode

EIA Base & Outline

47
Power Pentode

Application

Source ........................................ RCA R-10 - 1932
The '47 is a power amplifier pentode for usc in the audio output stage of a-c receivers. It is capable of giving large power output with a relatively small input signal voltage. In comparison with three-electrode power amplifiers of the same plate dissipation, the '47 is capable of greater power output with the additional feature of higher amplification. This power-handling ability of the '47 is made possible by the addition of both a suppressor and a screen between the grid and plate.

Mechanical Data

Source ........................................ RCA R-10 - 1932
Bulb .......................................... S-17
Base Type ..................................... Medium 5-Pin
EIA Outline ................................... 17-0
EIA Base ...................................... 5B
Mounting Position ............................. Vertical

Source ........................................ RCA RC-13 - 1937
Bulb .......................................... ST-16
EIA Outline ................................... 16-1

Electrical Data

Source ........................................ RCA RC-13 - 1937
Heater Voltage ................................ 2.5 V
Heater Current ................................ 1.75 A

Direct Interelectrode Capacitances (approx)

Pentode
Source ........................................ RCA R-10 - 1932
Input ......................................... 8.7 pf
Output ........................................ 13.2 pf
Grid to Plate ................................. 1.25 pf

Pentode
Source ........................................ RCA RC-13 - 1937
Input ......................................... 8.6 pf
Output ........................................ 13.0 pf
Grid to Plate ................................. 1.2 pf

Maximum Ratings (Design Center Values)

Pentode
Source ........................................ RCA R-10 - 1932
Plate Voltage ................................. 250 V
Grid No. 2 Voltage ............................ 250 V
Grid No. 1 Circuit Resistance
Fixed Bias ................................. 50K Ω
Self Bias .................................. 500K Ω

Characteristics and Typical Operation

Class A Amplifier
Source ........................................ RCA R-10 - 1932
Plate Voltage ................................. 250 V
Grid No. 2 Voltage ............................ 250 V
Grid No. 1 Voltage ............................ -16.5 V
Grid No. 1 Voltage Derived from
Cathode Bias Resistor ...................... 450 Ω
Amplification Factor .......................... 150
Plate Resistance (approx) ..................... 60K Ω
Transconductance .............................. 2500 µ
Plate Current ................................. 31 mA
Grid No. 2 Current ............................ 6 mA
Load Resistance ............................... 7K Ω
Power Output (approx) ......................... 2.5 W

Class A Amplifier
Source ........................................ RCA RC-13 - 1937
Plate Voltage ................................. 250 V
Grid No. 2 Voltage ............................ 250 V
Grid No. 1 Voltage ............................ -16.5 V
Grid No. 1 Voltage Derived from
Cathode Bias Resistor ...................... 450 Ω
Amplification Factor .......................... 150
Plate Resistance (approx) ..................... 60K Ω
Transconductance .............................. 2500 µ
Plate Current ................................. 31 mA
Grid No. 2 Current ............................ 6 mA
Load Resistance ............................... 7K Ω
Power Output (approx) ......................... 2.7 W

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(c) 1994-2021 by William A. Beech, NJ7P

Sat, 25 Jun 2022 16:12:20 -0700