6AU6
6AU6 is also designated EF94. Completed sales put the typical price at $8.97 per tube.
The 6AU6 is an indirectly heated RF pentode, intended for use as an RF or IF amplifier. Its heater, rated at 6.3 volts and a nominal 0.3 ampere, is designed for parallel operation with other valves in AC-operated equipment. The tube is mounted in a standard T5½ bulb and fitted with a B7G base.
Construction
The maximum overall length is 2-1/8 inches, the maximum diameter is 3/4 inch, and the maximum seated height is 1-19/32 inches. The maximum DC heater-cathode potential is 250 volts. Pin assignments are: pin 1, control grid (g1); pin 2, suppressor grid (g3) and internal shield; pins 3 and 4, heater connections; pin 5, anode; pin 6, screen grid (g2); pin 7, cathode.
Ratings
In pentode connection, the maximum anode voltage is 300 volts, the maximum screen voltage is 150 volts, and the maximum screen supply voltage is 300 volts. Maximum anode dissipation is 3.0 watts and maximum screen dissipation is 0.65 watt. In triode connection (with pins 2, 5, and 6 strapped), the maximum anode voltage is 250 volts and the maximum anode dissipation is 3.2 watts.
Characteristics
The mutual conductance is of the order of 5 mA/V. With pentode connections, the input capacitance is approximately 5.5 pF, the output capacitance is approximately 5.0 pF, and the grid-to-anode capacitance is 0.0035 pF maximum. With triode connections, the input capacitance is approximately 3.1 pF, the output capacitance is approximately 1.7 pF, and the grid-to-anode capacitance is approximately 2.5 pF.
Applications
The Brimar datasheet states that the high slope and short grid base make the 6AU6 very suitable for use as a limiter in FM receivers. It is also described as very efficient as an IF amplifier using intermediate frequencies around 10 Mc/s, and it may be employed as a grounded-grid amplifier at frequencies of the order of 100 Mc/s. The tube may also be used as a triode R-C coupled amplifier; in one example with an anode load of 220,000 ohms, the amplification factor is 29 and the anode impedance is 26,000 ohms.
| Designation | Evidence | Confidence |
|---|---|---|
| EF94 | 47 independent documents | confirmed |
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 | $8.97 |
| Typical range (25th–75th) | $5.11 – $18.57 |
| Most sales (10th–90th) | $2.98 – $61.59 |
| Extremes incl. outliers | $2.56 – $87.50 |
| Completed sales | 29 |
| Brand | Median | Range | Sales |
|---|---|---|---|
| GE | $8.97 | $7.59 – $23.09 | 7 |
| RCA | $6.60 | $5.66 – $61.59 | 4 |
| Sylvania | $3.87 | $2.56 – $5.00 | 3 |
| Raytheon | $10.95 | $3.48 – $15.99 | 3 |
| Condition | Median | Sales |
|---|---|---|
| NOS | $9.99 | 19 |
Per-tube prices from completed sales, 2026-08-31 to 2026-09-21. Matched pairs and quads are divided out. See the price index for how these move over time.
Original manufacturer datasheets for 6AU6, hosted by Frank Philipse's Electron Tube Data sheets.
| Manufacturer | Designation | Datasheet |
|---|---|---|
| Brimar | 6AU6 | PDF (2102 KB) |
| Mazda-Belvu | 6AU6 | PDF (443 KB) |
| Mullard | 6AU6 | PDF (286 KB) |
| Tung-Sol | 6AU6 | PDF (195 KB) |
| Brimar | 6AU6 | PDF (98 KB) |
| Lorenz | EF94 | PDF (163 KB) |
Documents held here and used to write this page.
- BRIMAR
- b) Triodenschaltung, Gitter 2 und Gitter 3 mit Anode verbunden (filed under EF94)