Description
3CW20000H3 is a water-cooled, ceramic-metal power triode with a robust mesh filament, for use in industrial radio-frequency heating
Electrical Characteristics 3CW20000H3
| Filament | Thoriated tungsten |
| Filament voltage (see note 1) | 7.5 V |
| Filament current | 100 A |
| Surge Filament current (peak) (see note 2) | 500 A |
| Filament cold resistance | 9.7 mΩ |
| Peak usable cathode current | 26 A |
| Amplification factor (Va = 2.3 kV, la = 1.0 A) | 20 |
| Mutual conductance (Va = 2.5 kV, la = 1.3 A) | 31 mA/V |
| Grid to anode | 39 pF |
| Grid to filament | 54 pF |
| Anode to filament | 2.0 pF |
Mechanical Characteristics of 3CW20000H3
Connections: Filament leads and grid contact flange
Operating position: vertical, either way up
Maximum operating temperature: 250 degree Centigrade
Maximum dimensions: See outline drawings
Net weight: 4 kg (8.8 pounds) approx
Accessories of 3CW20000H3
Water coupling, supplied with 3CW20000H3: CWPA323A
Thermal fuse available for 3CW20000H3: PA85E
Cathode connector: CWPA830
For frequencies above 2MHz, CWPA830 should be used in conjunction with a strip connection to provide a low inductance cathode return.
Cooling
Anode of 3CW20000H3 is cooled by circulating water through the removable anode water jacket. The table below lists the minimum water flow requirement for adequate anode cooling at various anode dissipation levels. In all cases, the outlet water temperature must not exceed 70 ⁰C nor should inlet water pressure exceed 60 psi. This table is based upon 20 ⁰C temperature rise.
Additional forced-air cooling of the tube base is also required to maintain ceramic-to-metal seal temperature below the 250 ⁰C maximum. Approximately 50 ft3/min of cooling air directed into the base structure will generally satisfy requirements.
Minimum Water Cooling Requirements of 3CW20000H3
| Anode Dissipation (kW) | Water Flow (l/min) | Pressure Drop (psi) |
| 10 | 12 | 2.5 |
| 15 | 13 | 3.0 |
| 20 | 15 | 3.5 |
| 25 | 18 | 4.0 |
The values given allow for maximum filament and grid dissipation in addition to anode dissipation shown.
Radio Frequency Oscillator For Industrial Service
(Class C Conditions, One Tube)
Maximum Ratings (Absolute Values)
| Frequency | 90 MHz max |
| Anode voltage d.c. | 10 kV max |
| Anode current d.c. (see note 3) | 4.0 A max |
| Anode input power | 40 kW max |
| Anode dissipation | 10 kW max |
| Grid voltage d.c. | –1000 V max |
| Grid current d.c. (See note 4) | 0.6 A max |
| Grid dissipation | 250 W max |
| Cathode current d.c. | 5.0 A max |
Typical Operating Conditions of 3CW20000H3
| Frequency | 30 | 30 MHz |
| Anode voltage d.c. | 7.0 | 9.0 kV |
| Anode current d.c. | 4.0 | 4.0 A |
| Anode dissipation | 9 | 7 kW |
| Grid voltage d.c. | -670 | -930 V |
| Grid resistor | 2450 | 2160 Ω |
| Grid current d.c. | 275 | 430 mA |
| Grid dissipation | 94 | 168 W |
| Drive power | 260 | 570 W |
| Anode input power | 28 | 36 kW |
| Anode output power | 19 | 29 kW |
| Output power less drive | 18.7 | 28.4 kW |
