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UCH81 — Triode-Hexode, Noval | Tubeofile
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UCH81
Triode-Hexode — Noval
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Philips
↗ TDSL
↗ Radiomuseum
Known Equivalents & Substitutes
X119
Similar Tubes (Not Drop-In Compatible)
19AJ8
American equivalent designation
ECH81
6.3 V heater version — same Noval base and pinout but different heater voltage
ECH83
Reportedly identical internally to ECH81 — same base and pinout
HCH81
12.6 V heater version — same pinout but different heater voltage
Electrical Specifications
Section 1 — Triode (Oscillator)
Absolute Maximum
Anode Voltage (max)
Anode Voltage (max)
250
V
Anode Dissipation (max)
Anode Dissipation (max)
0.8
W
Cathode Current (max)
Cathode Current (max)
6.5
mA
Max Grid Resistor
Grid Resistance (max)
3
MΩ
Typical Operating
Notes
Series-heater design (100 mA) for AC/DC receivers without heater transformer.
The 'U' prefix indicates 100 mA series-heater operation.
Triode and heptode sections share a common cathode.
Heptode conversion conductance Sc = 620 uA/V at Vb=100V, 750 uA/V at Vb=170V.
Brans lists equivalents: 19AJ8, 19D8, 10C14, X119.
Pin Layout — Noval
1
2
3
4
5
6
7
8
9
1
Heptode Anode
2
Heptode Screen Grid (g2+g4)
3
Common Cathode
Socket-Compatible Tubes
⚠ Not electrically compatible
ECH83
HCH81
References
https://frank.pocnet.net/sheets/050/u/UCH81.pdf
Anode Voltage (typical)
Anode Voltage (typical)
100
V
Grid 1 Bias Voltage
Grid Voltage
-2
V
Anode Current
Anode Current
7.3
mA
Anode Resistance
Internal Resistance
7,000
Ω
Transconductance
Transconductance
2.4
mA/V
Amplification Factor (μ)
Amplification Factor
17
—
Section 2 — Heptode (Mixer)
Absolute Maximum
Anode Voltage (max)
Anode Voltage (max)
250
V
Screen Voltage (max)
Screen Voltage (max, Ia<=1 mA)
250
V
Anode Dissipation (max)
Anode Dissipation (max)
1.7
W
Screen Dissipation (max)
Screen Dissipation (max)
1
W
Cathode Current (max)
Cathode Current (max)
12.5
mA
Max Grid Resistor
Grid 1 Resistance (max)
3
MΩ
Typical Operating
Anode Voltage (typical)
Anode Voltage (typical)
170
V
Screen Voltage (typical)
Screen Voltage (g2+g4, via 10 kohm resistor)
102
V
Anode Current
Anode Current
3.2
mA
Screen Current
Screen Current (g2+g4)
6.8
mA
Anode Resistance
Internal Resistance
Heater
Heater Voltage
Heater Voltage
19
V
Heater Current
Heater Current
0.1
A
,
Suppressor Grid (g5)
4
Heater
5
Heater
6
Triode Anode
7
Heptode Signal Grid (g1)
8
Triode Grid / Heptode Oscillator Grid (g3)
9
Internal shield
900,000
Ω
Transconductance
Conversion Conductance (Sc)
0.75
mA/V
Cathode Resistor (self-bias)
Cathode Resistor
150
Ω