5751
5751 has no equivalent designation confirmed by the archive. Completed sales put the typical price at $44.95 per tube.
Description
The 5751 is a high-mu nine-pin miniature twin triode tube with two triode sections, each with an individual cathode connection. It has a coated unipotential cathode and a T-6½ glass envelope. The tube is designed as a sturdy, vibration-resistant tube for industrial applications requiring dependable operation under rigorous service conditions, and is adapted to intermittent service conditions. It can be mounted in any position.
Heater Ratings
The heater may be connected for either series or parallel operation. For parallel operation, the heater voltage is 6.3 volts and heater current is 0.350 amperes. For series operation, the heater voltage is 12.6 volts and heater current is 0.175 amperes. The heater current is slightly higher than in conventional tubes of this type to provide a safety factor in cathode performance.
Maximum Ratings
Maximum ratings are given as design-center and absolute values. The maximum plate voltage is 300 volts (design center) or 330 volts (absolute). The maximum negative grid bias voltage is 50 volts (design center) or 55 volts (absolute). The maximum positive grid bias voltage is 0 volts. Maximum plate dissipation per section is 1.0 watt (design center) or 1.1 watts (absolute). The maximum peak heater-cathode voltage is 90 volts (design center) or 100 volts (absolute).
Typical Operation
In typical Class A amplifier operation at 6.3 volts heater voltage, 250 volts plate voltage, and -3 volts grid bias, the amplification factor is 70, plate resistance is 58000 ohms, transconductance is 1200 micromhos, and plate current is 1.0 milliampere.
Base Connections
Pin 1 is the plate of section No. 2, pin 2 is the grid of section No. 2, and pin 3 is the cathode of section No. 2. Pins 4 and 5 are the heater pins. Pin 6 is the plate of section No. 1, pin 7 is the grid of section No. 1, and pin 8 is the cathode of section No. 1. Pin 9 is the heater center-tap.
Mechanical
The envelope height is measured from base seat to bulb-top line as determined by a ring gage of 7/16 inch inside diameter.
| Measure | Per tube |
|---|---|
| Median | $44.95 |
| Typical range (25th–75th) | $32.00 – $74.95 |
| Most sales (10th–90th) | $21.44 – $114.50 |
| Extremes incl. outliers | $3.49 – $598.65 |
| Completed sales | 473 |
| Brand | Median | Range | Sales |
|---|---|---|---|
| GE | $38.50 | $29.95 – $50.75 | 192 |
| RCA | $56.50 | $36.95 – $74.99 | 83 |
| Sylvania | $63.62 | $45.68 – $91.47 | 69 |
| Raytheon | $86.50 | $66.20 – $110.00 | 29 |
| Tung-Sol | $41.00 | $34.99 – $50.68 | 24 |
| JJ | $27.14 | $22.95 – $39.98 | 8 |
| Siemens | $164.97 | $92.50 – $218.49 | 7 |
| Philips | $41.36 | $28.88 – $49.00 | 6 |
| Condition | Median | Sales |
|---|---|---|
| NOS | $59.99 | 199 |
| used | $37.49 | 169 |
| current | $29.69 | 18 |
Per-tube prices from completed sales, 2020-01-11 to 2026-11-08. Matched pairs and quads are divided out. See the price index for how these move over time.
Original manufacturer datasheets for 5751, hosted by Frank Philipse's Electron Tube Data sheets.
| Manufacturer | Designation | Datasheet |
|---|---|---|
| Mazda-Belvu | 5751 | PDF (673 KB) |
| Siemens | 5751 | PDF (226 KB) |
| RCA (HB3) | 5751 | PDF (218 KB) |
| Tung-Sol | 5751 | PDF (133 KB) |
| Siemens | 5751 | PDF (104 KB) |
Documents held here and used to write this page.
- TWIN TRIODE
1 further designation appears alongside 5751 in the literature but below the evidence threshold used here, so it is not listed as equivalent.