300B
300B has no equivalent designation confirmed by the archive. Completed sales put the typical price at $228.49 per tube.
The 300B is a moderate-power filamentary triode intended for Class A service, mounted on a 4-pin ceramic base.
Construction
The tube uses a directly heated filament rated at 5 V and approximately 1.3 A. Its inter-electrode capacitances are 17 pF from grid to cathode, 11 pF from anode to cathode, and 7.5 pF from grid to anode.
Ratings and Characteristics
At an anode voltage of 300 V and a grid voltage of −61 V, the anode current is 60 mA. Under these conditions the transconductance is 5.5 mA/V, the anode impedance is 700 ohms, and the amplification factor is 3.85. The maximum anode dissipation is 40 W at an anode voltage of 450 V. Maximum plate current is 70 mA with fixed bias and 100 mA with manually adjusted grid bias or self-biasing.
| Measure | Per tube |
|---|---|
| Median | $228.49 |
| Typical range (25th–75th) | $130.16 – $510.00 |
| Most sales (10th–90th) | $79.42 – $1,400.12 |
| Extremes incl. outliers | $12.47 – $4,849.00 |
| Completed sales | 150 |
| Brand | Median | Range | Sales |
|---|---|---|---|
| Western Electric | $551.99 | $360.05 – $1,350.00 | 56 |
| Psvane | $201.82 | $117.64 – $274.50 | 16 |
| Shuguang | $103.09 | $81.15 – $140.31 | 12 |
| Electro-Harmonix | $145.91 | $103.53 – $192.28 | 12 |
| Genalex/Gold Lion | $170.07 | $157.03 – $197.45 | 7 |
| JJ | $139.75 | $129.50 – $182.95 | 4 |
| Condition | Median | Sales |
|---|---|---|
| NOS | $360.05 | 35 |
| used | $500.00 | 46 |
| current | $159.02 | 63 |
Per-tube prices from completed sales, 2025-01-06 to 2026-11-07. Matched pairs and quads are divided out. See the price index for how these move over time.
Original manufacturer datasheets for 300B, hosted by Frank Philipse's Electron Tube Data sheets.
| Manufacturer | Designation | Datasheet |
|---|---|---|
| JJ | 300B | PDF (174 KB) |
| WE | 300B | PDF (135 KB) |
Documents held here and used to write this page.
- **300 B**