KT88
KT88 has no equivalent designation confirmed by the archive. Completed sales put the typical price at $100.50 per tube.
The KT88 is a beam power pentode in a tubular bulb with a metal shell wafer octal base, intended primarily for the output stage of an audio-frequency amplifier.
Construction
The maximum overall length is 125 mm, the maximum seated length is 110 mm, and the maximum diameter is 52 mm. The tube may be mounted horizontally only if pins 4 and 8 are in a vertical plane. The hottest part of the bulb should not exceed 250 degrees Celsius.
Ratings
The KT88 has a heater voltage of 6.3 V and a heater current of 1.6 A. Maximum ratings include an anode voltage of 600 V, a screen grid voltage of 600 V, an anode dissipation of 35 W, a screen grid dissipation of 6 W, a combined anode and screen grid dissipation of 40 W, a cathode current of 175 mA, and a heater-to-cathode voltage of 150 V. The maximum grid-to-cathode resistance is 220 kΩ with cathode bias and 100 kΩ with fixed bias. Inter-electrode capacitances are 1.2 pF grid-to-anode, 16 pF input, and 12 pF output.
Applications
Two valves in the output stage of an audio-frequency amplifier can provide up to 100 W output. Under intermittent conditions, an output of 150 W is obtainable in Class B. The KT88 is also suitable for use as a series valve in a stabilised power supply.
Characteristics
In pentode connection at Va = 250 V and Vg2 = 250 V, the anode current is 140 mA, the transconductance is 11 mA/V, and the anode impedance is 12 kΩ. In triode connection at Va,g2 = 250 V, the anode current is 160 mA, the transconductance is 12 mA/V, and the anode impedance is 670 Ω. The mu between g1 and g2 is 8.
| Measure | Per tube |
|---|---|
| Median | $100.50 |
| Typical range (25th–75th) | $80.08 – $230.95 |
| Most sales (10th–90th) | $58.70 – $407.35 |
| Extremes incl. outliers | $19.87 – $4,330.00 |
| Completed sales | 142 |
| Brand | Median | Range | Sales |
|---|---|---|---|
| Genalex/Gold Lion | $108.36 | $87.06 – $317.46 | 44 |
| GEC | $246.97 | $127.44 – $415.00 | 13 |
| Psvane | $86.14 | $70.55 – $131.96 | 10 |
| Svetlana | $80.75 | $40.51 – $100.49 | 10 |
| Mullard | $176.56 | $88.75 – $248.32 | 10 |
| Electro-Harmonix | $67.95 | $66.60 – $80.17 | 7 |
| JJ | $87.14 | $55.00 – $101.24 | 7 |
| Sovtek | $83.69 | $74.97 – $85.85 | 5 |
| Tung-Sol | $249.50 | $230.95 – $344.48 | 5 |
| Genalex | $172.46 | $140.42 – $250.00 | 4 |
| Shuguang | $39.13 | $30.00 – $91.27 | 3 |
| Condition | Median | Sales |
|---|---|---|
| NOS | $105.34 | 30 |
| used | $140.42 | 41 |
| current | $87.41 | 52 |
Per-tube prices from completed sales, 2021-05-28 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 KT88, hosted by Frank Philipse's Electron Tube Data sheets.
| Manufacturer | Designation | Datasheet |
|---|---|---|
| GEC | KT88 | PDF (618 KB) |
| M-O Valve | KT88 | PDF (424 KB) |
| JJ | KT88 | PDF (231 KB) |
Documents held here and used to write this page.
- KT88