6GM8
6GM8 has no equivalent designation confirmed by the archive. Completed sales put the typical price at $22.50 per tube.
Description
The 6GM8 is a frame-grid twin triode designed for low supply voltage applications. It has a T6½ bulb, an E9-1 base, and 9DE basing. The tube can be mounted in any position and has a coated, unipotential cathode.
Ratings
The 6GM8 heater requires 6.3 volts at 330 mA. Maximum ratings include a plate voltage of 30 volts, a plate dissipation of 0.6 watt, a cathode current of 20 mA, and a grid circuit resistance of 1 megohm. The maximum voltage between cathode and heater is 30 volts, and the maximum circuit resistance between cathode and heater is 20,000 ohms.
Characteristics
At a plate voltage of 6.3 volts and a grid voltage of −0.4 volt, the 6GM8 has a plate current of 0.9 mA, a transconductance of 2,600 micromhos, and an amplification factor of 14. Maximum inter-electrode capacitances are 0.05 μμf plate-to-plate, 0.005 μμf grid-to-grid, and 0.005 μμf between each plate and the opposite grid section.
Applications
The 6GM8 is suitable for instrumentation and industrial applications as a direct-coupled wide band amplifier. It is also suitable for automobile radio sets as an RF amplifier and self-oscillating mixer, and can be directly operated from a storage battery.
Base B9A, viewed from below (the wiring side), pins numbered clockwise from the key. Read from the datasheet's basing table and checked against it automatically — confirm against the original datasheet before wiring.
| Measure | Per tube |
|---|---|
| Median | $22.50 |
| Typical range (25th–75th) | $18.20 – $35.48 |
| Most sales (10th–90th) | $17.45 – $39.27 |
| Extremes incl. outliers | $15.98 – $44.48 |
| Completed sales | 18 |
| Brand | Median | Range | Sales |
|---|---|---|---|
| Amperex | $22.50 | $17.45 – $33.22 | 12 |
| Condition | Median | Sales |
|---|---|---|
| NOS | $22.50 | 15 |
| used | $18.20 | 3 |
Per-tube prices from completed sales, 2026-07-03 to 2026-09-07. Matched pairs and quads are divided out. See the price index for how these move over time.
Original manufacturer datasheets for 6GM8, hosted by Frank Philipse's Electron Tube Data sheets.
| Manufacturer | Designation | Datasheet |
|---|---|---|
| Amperex | 6GM8 | PDF (270 KB) |
Documents held here and used to write this page.
- 6GM8
1 further designation appears alongside 6GM8 in the literature but below the evidence threshold used here, so it is not listed as equivalent.