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EF805S — Small Signal Pentode, Noval | Tubeofile | Tubeofile
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EF805S
Small Signal Pentode — Noval — Telefunken
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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.
↗ Radiomuseum
Known Equivalents & Substitutes
EF85
EF865
6BY7
Similar Tubes (Not Drop-In Compatible)
19BY7
Brans Vademecum lists as equivalent. Same B9A base and similar characteristics but 19V series-string heater — not a drop-in in 6.3V heater circuits
Electrical Specifications
Absolute Maximum
Anode Voltage (max)
Ua max
250
V
Screen Voltage (max)
Ug2 max
250
V
Anode Dissipation (max)
Na
2
W
Screen Dissipation (max)
Ng2
0.5
W
Cathode Current (max)
Notes
Long-life tube: guaranteed 10,000 hours averaged over 100 tubes, provided heater voltage is kept within ±5%
Heater current differs between manufacturers: Telefunken specifies 285 mA, AEG specifies 300 mA
Pin 1 is internally connected to pin 3 (both cathode)
Rg1 max is 3 MΩ for automatic (cathode) bias, reduced to 1.5 MΩ for fixed bias
Free socket contacts must not be used for supporting any circuitry
EF85 is the standard-life equivalent but may differ slightly in heater current and max cathode current ratings
Pin Layout — Noval
1
2
3
4
5
6
7
8
9
1
Cathode (connected to pin 3)
2
Control Grid
3
Cathode (connected to pin 1)
Socket-Compatible Tubes
⚠ Not electrically compatible
6F23
6GK6
AL860
EF183
EF184
EF80
EF800
XF184
References
https://frank.pocnet.net/sheets/128/e/EF805S.pdf
https://frank.pocnet.net/sheets/173/e/EF805S.pdf
Ik
16
mA
Heater-to-Cathode Voltage (max)
Uf/k
100
V
Max Grid Resistor
Rg1 (auto bias)
3
MΩ
Typical Operating
Anode Voltage (typical)
Ua
200
V
Screen Voltage (typical)
Ug2
200
V
Grid 1 Bias Voltage
Ug1
-1.5
V
Anode Current
Ia
10
mA
Screen Current
Ig2
2.5
mA
Anode Resistance
Ri
350,000
Ω
Transconductance
S
6.5
mA/V
Capacitances
Grid-to-Plate Capacitance
Cg1a
0.007
pF
Grid-to-Cathode Capacitance
Cg1f
0.1
pF
Input Capacitance
Ce
7.7
pF
Output Capacitance
Ca
3.7
pF
other
Rk
Rk
120
Ω
Ua0 max (no current)
Ua0 max (no current)
550
V
Ug20 max (no current)
Ug20 max (no current)
550
V
Rg2 min
Rg2 min
45
kΩ
Heater
Heater Voltage
Uf
6.3
V
Heater Current
If
0.285
A
4
Heater
5
Heater
6
No Connection
7
Anode
8
Screen Grid
9
Suppressor Grid