Traveling Wave Tube (TWT)
A traveling wave tube (TWT) is a velocity-modulated tube that provides high-gain amplification at microwave frequencies, essential for satellite communications and military radar. It is classified here as an 'other' thermionic tube.
Import Duty Rates by Country of Origin
| Origin Country | MFN Tariff | Surtaxes | Total Effective Rate |
|---|---|---|---|
| 🇨🇳China | Free | — | Free |
| 🇲🇽Mexico | Free | — | Free |
| 🇺🇸United States | Free | — | Free |
| 🇩🇪Germany | Free | — | Free |
| 🇯🇵Japan | Free | — | Free |
Alternative Classifications
This product could be classified differently depending on its characteristics or intended use.
If the tube is a specific microwave tube type
Other microwave tubes may be classified under subheading 8540.79.
Not sure which classification is right?
The Tariff Assistant works through the GRI rules on your specific product to reach the right tariff item — and can price the duty on it in the same conversation.
Import Tips & Compliance
• Document the velocity modulation and slow-wave structure to support classification
• Ensure the tube is not part of a complete amplifier system
• Verify if the tube requires any export or import permits due to military applications
Related Products under Tariff item 8540.89.00
Cold Cathode Ion Gauge Tube
A cold cathode ion gauge tube is a vacuum measurement device that ionizes residual gas molecules through a high-voltage discharge between electrodes, generating a current proportional to pressure. It falls under this tariff item as an 'other' cold cathode tube used for ultra-high vacuum measurement.
Deuterium Arc Lamp Electrode Tube
A deuterium arc lamp electrode tube is a gas discharge tube filled with deuterium gas, producing a continuous UV spectrum for spectroscopy applications. It is classified here as an 'other' gas-filled tube where a cathode-initiated arc discharge generates light.
Grid-Controlled Vacuum Tube
A grid-controlled vacuum tube, such as a triode, uses a control grid to modulate electron flow from a heated cathode to an anode for amplification in audio and RF circuits. This thermionic tube falls under this tariff item as an 'other' valve or tube.
Hydrogen Thyratron Pulse Modulator Tube
A hydrogen thyratron is a gas-filled tube containing hydrogen gas at low pressure, designed for high-speed, repetitive high-voltage switching in pulse power applications like radar modulators. It is classified here as an 'other' gas-filled tube optimized for fast recovery.
Ignitron Mercury Arc Rectifier Tube
An ignitron is a large mercury arc rectifier tube used for high-current DC power conversion in industrial applications. It operates via a cathode pool and an ignition electrode, and is classified here as an 'other' mercury vapor-filled tube.
Klystron Power Amplifier Tube
A klystron is a linear beam vacuum tube that amplifies microwave signals through velocity modulation of an electron beam. It is used in high-power applications like radio transmitters and particle accelerators, and falls under this tariff item as an 'other' thermionic tube.