| GENERAL DESCRIPTION |
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The 4CX20,000A / 8990 is a ceramic/metal power tetrode intended for use in audio or radio-frequency applications. It features a type of internal mechanical structure which results in high rf operating efficiency. Low rf losses in this structure permit operation at full ratings up to 110 MHz. The 4CX20,000A / 8990 has a gain of over 18 dB in FM broadcast service, and is also recommended for radio-frequency linear power amplifier service, and for VHF television linear amplifier service. The anode is rated for 20 kW of dissipation with forced-air cooling and incorporates a highly efficient cooler of new design. |
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| TECHNICAL SPECIFICATIONS | |
| Plate Dissipation (Max.) | 20,000 watts |
| Screen Dissipation (Max.) | 450 watts |
| Grid Dissipation (Max.) | 200 watts |
| Frequency for Max. Ratings (CW) | 110 MHz |
| Cooling | Forced Air |
| Filament Voltage Current |
Thoriated Tungsten Mesh 10.0 volts 140 amperes |
| Capacitances (Grounded Cath. Connection) Input Output Feed-through |
190 pF 23.5 pF 1.5 pF |
| Capacitances (Grounded Grid Connection) Input Output Feed-through |
83 pF 24.5 pF 0.2 pF |
| Amplification Factor (g1-g2) | 6.7 |
| Base | Special, Coaxial |
| Recommended Air-System Socket | SK-320 |
| Recommended Air Chimney | SK-326 |
| Maximum Seal & Anode Core Temperature | 250°C |
| Maximum Length | 9.5 in; 241.3 mm |
| Maximum Diameter | 8.8 in; 223.5 mm |
| Weight (approximate) | 19.2 lb; 8.75 kg |
| 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 |
| Elcor | SW-20 K | 20 |
| SW-25 K | 25 | |
| THIS TUBE IS AVAILABLE FROM | ||
| Manufacturer | Rebuilder | Distributor |
| Eimac | Econco | Richardson Electronics |
| Penta Laboratories | Kennetron | |
| 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 |