| GENERAL DESCRIPTION |
 |
The 5-125B / 4E27A is a power pentode intended for use as a modulator, oscillator or amplifier. The driving-power requirement is very low, and neutralization problems are simplified or eliminated entirely. The tube has a maximum plate-dissipation rating of 125 watts and a maximum plate voltage rating of 4000 volts at frequencies up to 75 Mc. Cooling is by convection and radiation. Type 5-125B / 4E27A unilaterally replaces type 4E27 The 5-125B / 4E27A in class-C r-f service will deliver up to 375 watts plate power output with less than 2 watts driving power. It will deliver up to 75 watts of carrier for suppressor modulation. Two 5-125B / 4E27A's will deliver up to 300 watts maximum-signal plate power output in class AB1 modulator service, 400 watts in class AB2 with less than 1 watt driving power. |
 |
| TECHNICAL SPECIFICATIONS | |
| ELECTRICAL | |
| Filament, Thoriated Tungsten: Voltage Current |
5.0 ac or dc volts 7.5 amp |
| Transductance (Approx.) For plate volts = 2500, grid-No.3 volts = 0, grid-No.2 volts = 500, and plate ma. = 50 |
2150 μmhos |
| Mu Factor, Grid No.2 to Grid No.1 | 5 |
| Direct Interelectrode Capacitances: Grid No.1 to plate Input Output |
0.08 μμf 10.5 μμf 4.7 μμf |
| MECHANICAL | |
| Mounting Position | Vertical, base down or up |
| Maximum Overall Length | 5-9/16" |
| Seated Length | 5-3/8" ± 1/4" |
| Maximum Diameter | 2-3/4" |
| Weight | 6 ounces |
| Base | Ventilated Medium-Metal-Shell Giant 7-Pin |
| Seal Temperature (Plate and stem) | 225 max. °C |
| Bulb Temperature (At hottest point) | 250 max. °C |
| Specifications may change without notice | |
| THIS TUBE IS USED IN THE FOLLOWING SHORTWAVE BROADCAST TRANSMITTERS | ||
| Manufacturer | Transmitter specifications | Power in kW |
| RCA | BHF-50A | 50 |
| BHF-50B | 50 | |
| THIS TUBE IS AVAILABLE FROM | ||
| Manufacturer | Rebuilder | Distributor |
| 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 |