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417A — Small Signal Triode, Noval | Tubeofile | Tubeofile
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417A
Small Signal Triode — Noval — Western Electric
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Data: High
High quality — base, heater, all universal parameters present, and ≥50% of desirable parameters filled in. Safe to use for design decisions.
↗ r-type.org
↗ TDSL
↗ Radiomuseum
Known Equivalents & Substitutes
5842
WE417A
1547
Similar Tubes (Not Drop-In Compatible)
12AT7
Noval medium-mu triode (mu=60) but twin triode with higher ra (10900 ohms); different pinout
6AK5
Noval miniature tube used in similar telecom/instrumentation applications but is a pentode
6C45Pi
Single noval triode with very high gm and low ra; similar high-current low-impedance design philosophy
Electrical Specifications
Absolute Maximum
Anode Voltage (max)
Max. Plate Voltage
200
V
Anode Dissipation (max)
Max. Plate Dissipation
4.5
W
Cathode Current (max)
Max. Cathode Current
38
mA
Heater-to-Cathode Voltage (max)
Max. Heater-Cathode Voltage
55
V
Typical Operating
Notes
Originally designed by Western Electric for telephone repeater amplifier service.
The 5842 is the RETMA/JAN designation for the same tube as the 417A.
Single triode despite the Noval base; pins 4, 5, 7, and 8 are all connected to the grid for low inductance.
Very low plate resistance (1700 ohms) and high transconductance (25 mA/V) make it suitable as a low-impedance driver.
Widely used in high-end audio preamplifiers and microphone preamps.
Coated unipotential cathode; may be operated in any position.
RCA datasheet dated March 1962.
Pin Layout — Noval
1
2
3
4
5
6
7
8
9
1
Plate
2
No Internal Connection
3
Heater
Socket-Compatible Tubes
⚠ Not electrically compatible
AL860
References
https://frank.pocnet.net/sheets/049/5/5842.pdf
Anode Voltage (typical)
Plate Voltage
150
V
Grid 1 Bias Voltage
Grid Voltage
-9
V
Anode Current
Plate Current
25
mA
Anode Resistance
Plate Resistance
1,700
Ω
Transconductance
Transconductance
25
mA/V
Amplification Factor (μ)
Amplification Factor
43
—
Capacitances
Grid-to-Plate Capacitance
Grid-Plate Capacitance
1.8
pF
Input Capacitance
Cathode-Grid-Heater Capacitance
9
pF
Output Capacitance
Plate-Cathode-Heater Capacitance
0.55
pF
Heater
Heater Voltage
Heater Voltage
6.3
V
Heater Current
Heater Current
0.3
A
4
Grid
5
Grid
6
Cathode
7
Grid
8
Grid
9
Heater