6N8
6N8 is also designated EBF80. Completed sales put the typical price at $16.00 per tube.
The 6N8 is a double diode-variable-mu pentode with a coated unipotential cathode.
Construction
The 6N8 has a small button noval 9-pin base and a T-64 bulb. Maximum overall length is 2-3/8 inches, and maximum seated height is 2-3/32 inches. It can be mounted in any position. Basing connections use JETEC basing designation 9T-0-0.
Ratings
The heater requires 6.3 volts at 0.3 amperes. Maximum voltage between heater and cathode is 50 volts. For the pentode section, maximum plate voltage is 250 volts; maximum screen grid voltage is 550 volts, or 250 volts when plate current is less than 2.5 mA. For the diode sections, maximum plate voltage is 200 volts (peak value) and maximum plate current is 0.8 mA. If grid bias is obtained only by the voltage drop across the grid leak, the maximum grid resistor value is 22 megohms.
Capacitances
Direct interelectrode capacitances include 4.0 µµF between pentode grid No.1 and all other electrodes, 4.6 µµF between pentode plate and all other electrodes, and a maximum of 0.002 µµF between pentode plate and pentode grid No.1. Maximum capacitance between pentode grid No.1 and heater is 0.06 µµF. Diode capacitances are 2.15 µµF (diode No.1 plate to cathode) and 2.35 µµF (diode No.2 plate to cathode), with a maximum of 0.3 µµF between diode plates. Maximum capacitances between diode plates and heater are 0.02 µµF (diode No.1) and 0.01 µµF (diode No.2). Maximum capacitances between diode plates and grid No.1 are 0.0008 µµF (diode No.1) and 0.001 µµF (diode No.2), and between diode plates and pentode plate are 0.2 µµF (diode No.1) and 0.1 µµF (diode No.2).
Characteristics
The amplification factor of grid No.2 with respect to grid No.1 is 19. Equivalent noise resistance is 6,200 ohms. The Philips datasheet gives the transconductance as 2200 micromhos and the plate resistance as 1.6 megohms, both at a plate voltage of 250 volts. In circuits with a loudspeaker with an acoustical efficiency of 5%, this valve can be used without special precautions against microphony if the input voltage for an output of 50 milliwatts is more than 10 millivolts.
| Designation | Evidence | Confidence |
|---|---|---|
| EBF80 | 66 independent documents | strong |
Equivalence is asserted only where the archive's own literature states it directly, in at least 40 separate documents. Tubes that merely substitute in some circuits are not listed here.
| Measure | Per tube |
|---|---|
| Median | $16.00 |
| Typical range (25th–75th) | $7.75 – $46.49 |
| Most sales (10th–90th) | $4.80 – $77.50 |
| Extremes incl. outliers | $3.50 – $118.07 |
| Completed sales | 23 |
| Condition | Median | Sales |
|---|---|---|
| NOS | $14.38 | 16 |
| used | $29.99 | 4 |
Per-tube prices from completed sales, 2026-02-24 to 2026-09-24. Matched pairs and quads are divided out. See the price index for how these move over time.
Original manufacturer datasheets for 6N8, hosted by Frank Philipse's Electron Tube Data sheets.
| Manufacturer | Designation | Datasheet |
|---|---|---|
| Philips | 6N8 | PDF (322 KB) |
| Mazda-Belvu | EBF80 | PDF (445 KB) |
| Philips | EBF80 | PDF (425 KB) |
| Philips | EBF80 | PDF (265 KB) |
| RFT | EBF80 | PDF (133 KB) |
| Philips | EBF80 | PDF (86 KB) |
| Brimar | EBF80 | PDF (62 KB) |
Documents held here and used to write this page.
- EBF 80 Double diode-variable-mu pentode (filed under EBF80)
- Operating characteristics of the pentode section as A.F. amplifier in triode connection
2 further designations appear alongside 6N8 in the literature but below the evidence threshold used here, so they are not listed as equivalent.