7B4

Name: 7B4
Brand: Sylvania

Small Signal Triode — Loctal — Sylvania

Data: MediumMedium quality — at least 60% of universal parameters and pins are present, but some key data is missing. Verify specific values against datasheets before critical use.

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Known Equivalents & Substitutes

V879

Similar Tubes (Not Drop-In Compatible)

6SQ7

Equivalent triode section characteristics but Octal base with diode sections — different tube type and base

7A4

Sams lists as substitute — similar Loctal triode but verify electrical compatibility

Electrical Specifications

Absolute Maximum

Anode Voltage (max)Anode Voltage (max)300V

Typical Operating

Anode Voltage (typical)Anode Voltage (typical)250V

Grid 1 Bias VoltageGrid 1 Bias Voltage-2V

Anode CurrentAnode Current0.9mA

Notes

Loctal (lock-in) base — 8-pin base with metal locking ring. Not compatible with Octal or Noval sockets.
GE Essential Characteristics: Va_max 300 V, Va(typ) 250V, Vg=-2V, Ia=0.9mA, Rp=66000, gm=1500, mu=100.
Brans Vademecum lists V879 as the equivalent.
Sams lists 7A4 and XXL as substitutes.
Raytheon data shows a different operating point: Va=250V, Vg=-2V, Ia=0.5mA, gm=1500, Rp=12000 — the lower Rp suggests different measurement conditions.
The high mu (approximately 100) makes this tube suitable for high-gain voltage amplifier stages.

Pin Layout — Loctal

1No Connection

2Heater

3Anode

4

Socket-Compatible Tubes ⚠ Not electrically compatible

7C5 EF54 EL61

References