EL84
EL84 is also designated 6BQ5. Completed sales put the typical price at $43.41 per tube.
Description
The EL84 is an output pentode of all-glass miniature construction with a nine-pin base, intended for low-frequency class A, AB and B power amplifiers in broadcast receivers and amplifiers. The suppressor grid g3 is internally connected to the cathode. It has indirect heating, an oxide cathode, and parallel AC supply.
Construction and Ratings
The tube uses a nine-pin base designated S 9/12 according to ČSN 35 8904, and weighs approximately 20 g. The heater requires 6.3 V at 0.76 A. Maximum voltage between cathode and heater is 100 V; maximum external resistance between cathode and heater is 20 kΩ. The maximum negative grid voltage at which grid current starts (Ig1 = +0.3 μA) is 1.3 V.
Maximum ratings include: anode voltage, cold, 550 V; anode voltage, operating, 300 V; anode dissipation, 12 W; screen-grid voltage, cold, 550 V; screen-grid voltage, operating, 300 V; screen-grid dissipation at zero signal, 2 W; screen-grid dissipation at full drive, 4 W; negative control-grid voltage, 100 V; cathode current, 65 mA; control-grid leak resistance with fixed bias, 300 kΩ; with automatic bias, 1 MΩ.
Capacitances
Input capacitance Cg1 is 11 pF, output capacitance Ca is 6 pF, transfer capacitance Ca/g1 is less than or equal to 0.7 pF, and capacitance between control grid and filament Cg1/f is less than 0.25 pF.
Characteristics
With an anode voltage of 250 V, screen-grid voltage of 250 V, and a cathode resistor of 135 Ω, the transconductance is 11.3 mA/V and the internal resistance is 30 kΩ.
| Designation | Evidence | Confidence |
|---|---|---|
| 6BQ5 | 89 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 | $43.41 |
| Typical range (25th–75th) | $27.72 – $71.99 |
| Most sales (10th–90th) | $17.21 – $95.14 |
| Extremes incl. outliers | $2.68 – $328.00 |
| Completed sales | 233 |
| Brand | Median | Range | Sales |
|---|---|---|---|
| Mullard | $67.38 | $40.72 – $114.25 | 20 |
| GE | $56.48 | $37.76 – $76.97 | 19 |
| Telefunken | $105.24 | $82.49 – $122.36 | 19 |
| JJ | $30.90 | $23.12 – $43.41 | 17 |
| Amperex | $64.80 | $35.72 – $76.11 | 15 |
| Valvo | $76.80 | $70.96 – $79.06 | 9 |
| Sovtek | $35.23 | $27.82 – $45.33 | 9 |
| RCA | $50.89 | $29.95 – $62.49 | 8 |
| Philips | $66.12 | $50.73 – $82.12 | 6 |
| Siemens | $74.23 | $71.11 – $78.00 | 6 |
| Sylvania | $48.05 | $39.22 – $68.86 | 5 |
| Tung-Sol | $48.80 | $36.82 – $75.69 | 4 |
| Condition | Median | Sales |
|---|---|---|
| NOS | $68.15 | 87 |
| used | $36.72 | 81 |
| current | $37.43 | 44 |
Per-tube prices from completed sales, 2023-02-01 to 2026-09-05. Matched pairs and quads are divided out. See the price index for how these move over time.
Original manufacturer datasheets for EL84, hosted by Frank Philipse's Electron Tube Data sheets.
| Manufacturer | Designation | Datasheet |
|---|---|---|
| Tesla | EL84 | PDF (3293 KB) |
| Brimar | EL84 | PDF (869 KB) |
| Mullard | EL84 | PDF (802 KB) |
| Mazda-Belvu | EL84 | PDF (749 KB) |
| Ei | EL84 | PDF (612 KB) |
| Philips | EL84 | PDF (523 KB) |
| Philips | EL84 | PDF (382 KB) |
| JJ | EL84 | PDF (175 KB) |
| La Radiotechnique | EL84 | PDF (80 KB) |
| General Electric | 6BQ5 | PDF (652 KB) |
| Tung-Sol | 6BQ5 | PDF (645 KB) |
| RCA (HB3) | 6BQ5 | PDF (170 KB) |
Documents held here and used to write this page.
- EL84
- 6BQ5-8BQ5 PENTODE (filed under 6BQ5)
2 further designations appear alongside EL84 in the literature but below the evidence threshold used here, so they are not listed as equivalent.