4CX20000A Tubes For Sale: 4CX20000A Tube Specs, Data Sheet & Substitute Info
4CX20000A tubes for sale
Single or multiple 8890 / 4CX20000A tubes for sale: Available quantities:
If you are looking for an 8990 / 4CX20000A tube for sale, the usual goal is to match the tube already installed in your transmitter or RF system without creating fit or cooling problems during replacement. This page is designed to help buyers confirm the basic tube family, key ratings, and mechanical details before ordering a 4CX20000A replacement. Because these tubes are used in high-power applications, checking the installed designation, socket arrangement, and airflow setup before purchase is just as important as matching the number on the envelope.
4CX20000A tube specs
The table below gives a general overview of the 4CX20000A so you can quickly confirm the main characteristics. For full operating limits, curves, cooling tables, and dimensional detail, use the data sheet download below.
4CX20000A general specifications
| Specification | Details |
|---|---|
| Tube type | Ceramic/metal power tetrode (4CX20,000A / 8990) |
| Plate dissipation (max) | 20,000 W |
| Screen dissipation (max) | 450 W |
| Control grid dissipation (max) | 200 W |
| Maximum frequency for full ratings (CW) | 110 MHz |
| Amplification factor (Mu) | 6.7 |
| Filament/cathode type | Thoriated tungsten mesh |
| Filament voltage | 10.0 V |
| Filament current | 140 A |
| Interelectrode capacitance (grounded cathode): input | 190 pF |
| Interelectrode capacitance (grounded cathode): output | 23.5 pF |
| Interelectrode capacitance (grounded cathode): feedthrough | 1.5 pF |
| Interelectrode capacitance (grounded grid): input | 83 pF |
| Interelectrode capacitance (grounded grid): output | 24.5 pF |
| Interelectrode capacitance (grounded grid): feedthrough | 0.2 pF |
| Cooling method | Forced air |
| Base type | Coaxial |
| Socket/chimney note | Confirm against the installed hardware and data sheet before ordering; published references for this tube family include HF/coaxial socket use and SK-320 / SK-326 air-system hardware references |
| Overall length | 9.84 in (250 mm max) |
| Overall diameter | 8.80 in (22.4 cm) |
| Weight | 14.0 lb (6.35 kg net) |
| Operating position | Axis vertical, base up or down |
4CX20000A tube data sheet download
Download the 4CX20000A data sheet to review detailed ratings, characteristic curves, airflow requirements, and dimensional information before purchase.
4CX20000A tube substitute & equivalent information
The 4CX20000A is commonly identified with the 8990 designation, so that is the first cross-reference to check when replacing an installed tube. In practical buying terms, the most useful 4CX20000A tube equivalent is usually another 4CX20,000A / 8990 built to the same operating class and matched to the same mechanical and cooling setup. Published equivalent-product literature also describes this family as a direct replacement for U.S.-manufactured 4CX20,000A / 8990 tubes. :contentReference[oaicite:1]{index=1}
For replacement work, do not rely on the number alone. Confirm the marking on the tube being removed, then verify socket style, chimney or airflow path, mounting orientation, and the operating conditions in the transmitter or amplifier. That extra check matters because published references for this tube family do not all describe the accessory hardware the same way, even though they agree on the core electrical characteristics.
The Penta Laboratories 4CX20000A can be used as a direct replacement for 4CX20000A Eimac tubes where the installed tube designation and operating requirements align. Penta also offers related options for other applications, including HiFi tubes, tetrode products, and a broader ham radio tube range.
If you want to validate fit before ordering, contact Penta Laboratories with the details from the tube being replaced and the equipment it is installed in. As an established vacuum tubes producer, Penta can help confirm whether the 4CX20000A replacement you are considering matches your application.
Be the First to Know. Sign up to newsletter today.