The 4-250A / QB3.5/750GA is cooled by radiation from the plate and by circulation of forced-air through the base, around the envelope, and over the plate seal.
| GENERAL DESCRIPTION |
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The 4-250A / QB3.5/750GA is intended for use as an amplifier, oscillator or modulator. The low grid-plate capacitance of this tetrode coupled with its low driving-power requirement allows considerable simplification of the associated circuit and driver stage. The 4-250A / QB3.5/750GA is cooled by radiation from the plate and by circulation of forced-air through the base, around the envelope, and over the plate seal. |
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| TECHNICAL SPECIFICATIONS | |
| Plate Dissipation (Max.) | 250 watts |
| Screen Dissipation (Max.) | 35 watts |
| Grid Dissipation (Max.) | 10 watts |
| Frequency for Max. Ratings (CW) | 110 MHz |
| Cooling | Radiation & Forced Air |
| Filament Voltage Current |
Thoriated Tungsten 5.0 volts 14.5 amperes |
| Capacitances (Gnd. Cath. Connection) Input Output Feed-through |
12.7 pF 4.5 pF 0.12 pF |
| Amplification Factor (g1-g2) | 5.1 |
| Transconductance | 4000 µmhos |
| Base | 5-Pin Special |
| Recommended Air-System Socket | SK-410 |
| Recommended Air Chimney | SK-406 |
| Recommended Heat Dissipating Connector | HR-6 |
| Maximum Plate Seal Temperature | 200°C |
| Maximum Base Seal Temperature | 170°C |
| Maximum Length | 6.38 in; 162.00 mm |
| Maximum Diameter | 3.56 in; 90.40 mm |
| Weight (approximate) | 8 oz; 227 gm |
| Operating Position | Vertical, base up or down |
| Specifications may change without notice | |
| THIS TUBE IS USED IN THE FOLLOWING SHORTWAVE BROADCAST TRANSMITTERS | ||
| Manufacturer | Transmitter specifications | Power in kW |
| Collins | 207A-1 | 10 |
| 207B-1 | 35 | |
| Gates | BHF-10 | 10 |
| HF-20 / HF-20 B | 20 | |
| HF-100 | 100 | |
| THIS TUBE IS AVAILABLE FROM | ||
| Manufacturer | Rebuilder | Distributor |
| Covimag | Richardson Electronics | |
| Penta Laboratories | ||
| PRICE LEVEL (US$) | |||||
| 1 | 2 | 3 | 4 | 5 | 6 |
| 0 - 10 | 10 - 100 | 100 - 1000 | 1000 - 10,000 | 10,000 - 50,000 | 50,000 - 100,000 |