TUBE: 2A3
SOURCE FILE: sheets/049/2/2A3.pdf
MANUFACTURER: RCA (RCA Radiotron Division / RCA Manufacturing Co.) — curves also branded Cunningham Radiotron
YEAR: data October 15, 1947; characteristic curves March 9, 1933 & June 12, 1933
PAGES: 4 (pages 1-2 data, 3-4 curves)
TYPE (per PDF): POWER TRIODE

TYPOLOGY EVIDENCE: Title "2A3 POWER TRIODE". Single grid (Pin 3 = Grid). Directly heated filament 2.5V/2.5A. Base "Medium-Shell Small 4-Pin", basing designation 4D. -> directly-heated power TRIODE.

===== PAGE 1 =====
RCA — 2A3 — POWER TRIODE
GENERAL DATA
Electrical — Filament, Coated:
  Voltage   2.5  ac or dc volts
  Current   2.5  amp
Direct Interelectrode Capacitances (Approx.; with no external shield):
  Grid to Plate     16.5  uuf (pF)
  Grid to Cathode    7.5  uuf (pF)
  Plate to Cathode   5.5  uuf (pF)
Mechanical:
  Mounting Position: Any
  Maximum Overall Length: 5-3/8"
  Maximum Seated Length: 4-3/4"
  Maximum Diameter: 2-1/16"
  Bulb: ST-16
  Base: Medium-Shell Small 4-Pin ; Basing Designation for BOTTOM VIEW: 4D
  Pin 1 = Filament ; Pin 2 = Plate ; Pin 3 = Grid ; Pin 4 = Filament

AMPLIFIER — Class A1
Maximum Ratings, Design-Center Values:
  PLATE VOLTAGE     300 max. volts
  PLATE DISSIPATION  15 max. watts
Typical Operation and Characteristics:
  Plate Voltage          250   volts
  Grid Voltage #         -45   volts
  Amplification Factor    4.2
  Plate Resistance       800   ohms
  Transconductance      5250   umhos
  Plate Current           60   ma.
  Load Resistance       2500   ohms
  Second Harmonic Distortion  5  %
  Power Output           3.5   watts
Maximum Circuit Values:
  Grid-Circuit Resistance: fixed bias 0.05 max. megohm / cathode bias 0.5 max. megohm

===== PAGE 2 =====
PUSH-PULL AMPLIFIER — Class AB1
Maximum Ratings, Design-Center Values:
  PLATE VOLTAGE     300 max. volts
  PLATE DISSIPATION  15 max. watts
Typical Operation (values for 2 tubes):       Fixed Bias | Cathode Bias
  Plate Voltage              300 | 300   volts
  Grid Voltage #             -62 | —     volts
  Cathode-Bias Resistor      — | 780     ohms
  Peak AF Grid-to-Grid Voltage  124 | 156  volts
  Zero-Signal Plate Current   80 | 80    ma.
  Max-Signal Plate Current   147 | 100   ma.
  Effective Load Resistance (plate to plate)  3000 | 5000  ohms
  Total Harmonic Distortion  2.5 | 5.0   %
  Power Output                15 | 10    watts
Maximum Circuit Values:
  Grid-Circuit Resistance: fixed bias 0.05 max. megohm / cathode bias 0.5 max. megohm
Notes: # Grid voltage referred to mid-point of ac-operated filament. When a single 2A3 is cathode-biased, cathode-biasing resistor = 750 ohms.
[courbes] AVERAGE CHARACTERISTICS, TYPE 2A3, Ef=2.5V DC (plate mA vs grid volts; Eb=400/300/200/100).

===== PAGE 3 =====
[courbes seules — pas de données tabulaires]
RCA / Cunningham Radiotron RCA-2A3, AVERAGE PLATE CHARACTERISTICS, Ef=2.5V DC (plate mA vs plate volts, grid-volts parameter, load-resistance line; March 9 1933).

===== PAGE 4 =====
[courbes seules — pas de données tabulaires]
RCA / Cunningham Radiotron RCA-2A3, AVERAGE CHARACTERISTICS, Ef=2.5V DC: plate resistance (rp), mutual conductance (gm) and amplification factor (mu) vs plate volts, grid-volts -30/-40/-50/-60 (June 12 1933). Confirms mu~4.2, rp~800 ohm, gm~5250 umhos region.