6973
6973 has no equivalent designation confirmed by the archive. Completed sales put the typical price at $23.75 per tube.
The 6973 is a beam power tube of the 9-pin miniature class, intended for high-fidelity audio-amplifier applications.
Construction
The RCA datasheet describes the 6973 as having a Small-Button Noval 9-pin base (JEDEC No. E9-1) with a bulb designation of 16-1/2. Maximum dimensions are given as 3-1/16 inches overall length, 2-13/16 inches seated length, 2-7/16 inches from base seat to bulb top (excluding tip), and 0.750 inch diameter. Pin connections are: pin 1 grid No. 2, pin 2 no connection, pin 3 grid No. 1, pin 4 heater, pin 5 heater, pin 6 grid No. 3 and cathode, pin 8 grid No. 2, and pin 9 plate.
Ratings
Per the RCA datasheet, the heater is rated at 6.3 volts for a unipotential cathode. Maximum ratings include: grid No. 2 input power, 1.75 watts; peak heater-cathode voltage with heater negative with respect to cathode, 200 volts; bulb surface temperature, 250 degrees Celsius; and grid No. 1 to plate capacitance, 0.4 micromicrofarads maximum. The maximum grid-No.1-circuit resistance is 0.5 megohm for fixed-bias operation and 1 megohm for cathode-bias operation. The datasheet also lists grid No. 1 to cathode and grid No. 3 capacitance values.
Typical Operation
The RCA datasheet provides typical operation values for two tubes in push-pull Class AB1 audio-frequency power amplifier service, for both fixed and cathode bias. For fixed bias, the plate-supply voltage is 375 volts, grid-No.1 voltage is -33.5 volts, zero-signal cathode current is 62 mA, max-signal cathode current is 95 mA, effective load resistance (plate to plate) is 12,500 ohms, total harmonic distortion is 1.5%, and power output is 18.5 watts. For cathode bias, the plate-supply voltage is 370 volts, cathode resistor is 355 ohms, zero-signal cathode current is 74 mA, max-signal cathode current is 84 mA, effective load resistance (plate to plate) is 13,000 ohms, total harmonic distortion is 1.2%, and power output is 15 watts. Separate characteristics are also given for Class A1 amplifier operation at a plate voltage of 250 volts.
| Measure | Per tube |
|---|---|
| Median | $23.75 |
| Typical range (25th–75th) | $12.40 – $29.99 |
| Most sales (10th–90th) | $8.00 – $52.49 |
| Extremes incl. outliers | $3.18 – $65.00 |
| Completed sales | 35 |
| Brand | Median | Range | Sales |
|---|---|---|---|
| RCA | $28.24 | $21.30 – $35.95 | 21 |
| Electro-Harmonix | $26.31 | $24.98 – $38.66 | 4 |
| GE | $12.40 | $9.59 – $17.50 | 3 |
| Condition | Median | Sales |
|---|---|---|
| NOS | $23.67 | 16 |
| used | $20.20 | 12 |
| current | $26.31 | 4 |
Per-tube prices from completed sales, 2026-07-13 to 2026-09-18. Matched pairs and quads are divided out. See the price index for how these move over time.
Original manufacturer datasheets for 6973, hosted by Frank Philipse's Electron Tube Data sheets.
| Manufacturer | Designation | Datasheet |
|---|---|---|
| RCA (HB3) | 6973 | PDF (415 KB) |
Documents held here and used to write this page.
- **Beam Power Tube**