7308
7308 is also designated E188CC. Completed sales put the typical price at $69.74 per tube.
Description
The 7308 is a T-6½ duo triode with a coated unipotential cathode, designed for use as a multivibrator, cathode follower, VHF amplifier and VHF cascode amplifier. It is a special quality twin triode similar to the Sylvania Type 6922. The Sylvania datasheet for the 7308 was prepared and released by the Technical Publications Section, Emporium, Pennsylvania in June 1963.
Construction
The 7308 has a base of E9-1, miniature button 9-pin, and an outline of 6-2. The interelectrode capacitance between plate and grid (either section) is .005 pf, and between grid and cathode (either section) is .005 pf.
Ratings
The heater voltage is 6.3 Volts with a heater current of 335 mA. Maximum heater-cathode voltage is 120 Volts total DC and peak when the heater is negative with respect to the cathode, and 60 Volts total DC and peak when the heater is positive with respect to the cathode. Maximum plate voltage is 550 Volts with a cold cathode, 400 Volts at Ib = 0 mA, and 250 Volts under normal operation. Maximum plate dissipation is 1.65 Watts, with a maximum of 2.0 Watts or 2.2 Watts for both plates depending on the rating condition. Maximum grid dissipation is .03 Watts. Maximum cathode current is 22 mA, with a maximum peak cathode current of 110 mA. Maximum negative grid voltage is 110 Volts, with a maximum peak negative grid voltage of 200 Volts. Maximum bulb temperature is 165 ℃. Maximum grid circuit resistance is 0.5 Megohm for fixed bias and 1.0 Megohm for self bias.
Mechanical Ratings
A shock rating of about 500 g was obtained by using the NRL impact machine to deliver 5 blows to the tube at an angle of 30° in each of four different directions. A fatigue rating of 2.5 g was obtained by applying vibrational forces for 32 hours in each of three directions at a frequency of 50 cps.
| Designation | Evidence | Confidence |
|---|---|---|
| E188CC | 48 independent documents | confirmed |
Equivalence is asserted only where the archive's own literature states it directly, in at least 40 separate documents. Tubes that merely substitute in some circuits are not listed here.
| Measure | Per tube |
|---|---|
| Median | $69.74 |
| Typical range (25th–75th) | $49.99 – $150.00 |
| Most sales (10th–90th) | $31.50 – $235.00 |
| Extremes incl. outliers | $7.17 – $529.50 |
| Completed sales | 146 |
| Brand | Median | Range | Sales |
|---|---|---|---|
| Amperex | $82.62 | $51.48 – $140.00 | 78 |
| Sylvania | $46.59 | $33.36 – $54.90 | 16 |
| RCA | $177.50 | $75.08 – $235.00 | 8 |
| Telefunken | $215.03 | $185.00 – $502.50 | 7 |
| Siemens | $163.48 | $57.99 – $192.46 | 6 |
| Philips | $92.75 | $80.67 – $166.68 | 5 |
| Valvo | $187.41 | $176.34 – $387.19 | 4 |
| Condition | Median | Sales |
|---|---|---|
| NOS | $120.00 | 69 |
| used | $67.09 | 40 |
Per-tube prices from completed sales, 2022-03-16 to 2026-10-13. Matched pairs and quads are divided out. See the price index for how these move over time.
Original manufacturer datasheets for 7308, hosted by Frank Philipse's Electron Tube Data sheets.
| Manufacturer | Designation | Datasheet |
|---|---|---|
| Sylvania | 7308 | PDF (383 KB) |
| Philips | E188CC | PDF (973 KB) |
| Siemens | E188CC | PDF (497 KB) |
| Philips | E188CC | PDF (453 KB) |
Documents held here and used to write this page.
- **PHILIPS** (filed under E188CC)
- engineering data service