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6BR7 — Sharp Cutoff Pentode, Noval | Tubeofile
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6BR7
Sharp Cutoff Pentode — Noval
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Known Equivalents & Substitutes
6059
CV5215
Similar Tubes (Not Drop-In Compatible)
6267
American designation for EF86 — similar function but different pinout
EF86
Similar low-noise pentode on Noval base with higher Gm (1.8 vs 1.25 mA/V) — different operating points, not pin-compatible
Electrical Specifications
Absolute Maximum
Anode Voltage (max)
Anode Voltage (max)
300
V
Screen Voltage (max)
Screen Voltage (max)
125
V
Anode Dissipation (max)
Anode Dissipation (max)
1.75
W
Typical Operating
Anode Voltage (typical)
Anode Voltage (typical)
250
V
Screen Voltage (typical)
Screen Voltage (typical)
100
V
Grid 1 Bias Voltage
Grid Voltage
-3
V
Anode Current
Anode Current
2.1
mA
Screen Current
Screen Current
Heater
Heater Voltage
Heater Voltage
6.3
V
Heater Current
Heater Current
0.15
A
Notes
The 6BR7 is specifically designed for low-noise microphone and pickup preamplifier applications.
Typical operating conditions at Va=250V, Vg2=100V, Vg1=-3V: Ia=2.1mA, Ig2=0.6mA, Rp=2.5MΩ, Gm=1250 umhos.
Maximum ratings: plate voltage 300V, screen voltage 125V, plate dissipation 1.75W.
The low plate current and high Rp make this tube unsuitable as a general-purpose pentode — it is specifically optimised for low-noise voltage gain.
Pin Layout — Noval
1
2
3
4
5
6
7
8
9
1
Internal Shield
2
Anode
3
Suppressor Grid (g3)
References
https://frank.pocnet.net/sheets/019/6/6BR7.pdf
https://tdsl.duncanamps.com/show.php?des=6BR7
0.6
mA
Anode Resistance
Anode Resistance
2,500,000
Ω
Transconductance
Transconductance
1.25
mA/V
4
Heater
5
Heater
6
Screen Grid (g2)
7
No Connection
8
Cathode
9
Control Grid (g1)