TUBE 4CX20,000A / 8990

GENERAL DESCRIPTION


photo 4CX20,000A The 4CX20,000A is a power tetrode intended for use in audio or radio frequency applications. It features an 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 and at reduced ratings to 220 MHz.
The 4CX20,000A 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-TV linear amplifier service. The anode is rated for 20 kW of dissipation with forced-air cooling and incorporates a new highly efficient cooler design, which significantly reduces air pressure and flow requirements and produces low acoustical noise.


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