| GENERAL DESCRIPTION |
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The 813 / QB2/250 is a general-purpose transmitting beam power tube of the thoriated-tungsten filament type designed for use as an rf power amplifier and oscillator as well as an af power amplifier and modulator. The 813 / QB2/250 has a maximum plate dissipation of 125 watts under ICAS conditions in modulator service and cw service. In the latter service it can be operated with full input to 30 Mc and with reduced input to 120 Mc. Because of its high power sensitivity, the 813 / QB2/250 requires very little driving power to give full power output. For example, in class C telegraph service under ICAS conditions, a single 813 / QB2/250 is capable of giving a power output of approximately 375 watts with a driving power of only about 4 watts. |
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| TECHNICAL SPECIFICATIONS | ||||
| ELECTRICAL | ||||
| Min. | Bogey | Max. | ||
| Filament Voltage | 9.5 | 10 | 10.5 | volts |
| Filament Current at Bogey Voltage | 4.7 | 5 | 5.3 | amp |
| Transconductance | 3750 μmhos | |||
| Amplification factor | 8.5 | |||
| Interelectrode Capacitances, measured without external shielding G1 to Plate Input, G1 to Filament, G2 and G3 Output, plate to filament, G2 and G3 |
13 10.5 |
16.3 14 |
0.25 19.6 17.5 |
μμf μμf μμf |
| MECHANICAL | ||||
| Mounting Position |
Vertical, base up or down Horizontal, plate in vertical plane |
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| Basing | JETEC 5BA | |||
| Cap, medium | JETEC C1-5 | |||
| Base, medium metal-shell, giamt 7-pin bayonet | JETEC A7-17 | |||
| Bulb | T-20 | |||
| Net Weight, approximate | 8 oz. | |||
| Shipping Weight | 2.5 lbx | |||
| Specifications may change without notice | ||||
| THIS TUBE IS USED IN THE FOLLOWING SHORTWAVE BROADCAST TRANSMITTERS | ||
| Manufacturer | Transmitter specifications | Power in kW |
| Gates | HF-50 C | 50 |
| HF-100 C | 100 | |
| Marconi | BD 272 | 250 |
| RCA | BHF-10A | 10 |
| BHF-50A | 50 | |
| BHF-50B | 50 | |
| THIS TUBE IS AVAILABLE FROM | ||
| Manufacturer | Rebuilder | Distributor |
| Penta Laboratories | Richardson Electronics | |
| Vacuum Tubes, Inc. | ||
| 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 |