Sourcing travelling-wave tubes from China

UK duty on travelling-wave tubes

Heading 8540 covers thermionic, cold cathode and photocathode valves and tubes. Travelling-wave tubes fall within the other microwave tubes line, 8540 79 00 90. The table shows different uses sharing that line, alongside the other parts line, 8540 99 00 90. For wider heading coverage, see our klystron tubes guide.

Read from the UK Trade Tariff on 2 October 2026, both relevant lines carried 0% duty for goods from China. The supplied tariff record lists no anti-dumping or countervailing duty, suspensions or attached import controls for these lines.

Confirm the commodity code using the manufacturer's datasheet and a description of what is shipped. Identify whether the order contains a tube, tube parts or an assembled amplifier. Budget separately for import VAT using our duty and VAT guide.

Specify the tube and its operating conditions

Specify the manufacturer's type, intended equipment, frequency band, gain, output power and whether operation is continuous or pulsed. Agree the supply voltages, beam and heater requirements, input and output interfaces, mounting dimensions and cooling arrangements. Ask for performance records tied to the supplied serial number, with the test conditions stated.

Confirm whether the tube is new, unused stock or refurbished, and agree an acceptance test in the intended system. Component parts sold between businesses are outside the scope of the hazardous-substance regulations described in official Great Britain guidance. Components incorporated into an in-scope finished electrical product must support that product's compliance; obtain material declarations and details of any exemption relied upon.

Finished equipment must comply with all applicable legislation when placed on the Great Britain market. Identify the intended supply route before ordering and arrange a testing and certification review where the scope is unclear.

Worked duty example

Illustrative example, not a quote: Illustrative order: a replacement travelling-wave tube for a business test system under 8540 79 00 90, invoiced at £30,000 free on board, with £900 of freight and insurance to the UK. The customs value is £30,900. Duty at 0% is £0. Import VAT at 20% is charged on the customs value plus duty, £30,900, so it is £6,180. With no duty, the only import tax is the VAT, which a VAT-registered importer can usually reclaim. The import duty and VAT guide explains each step.

Inspection checklist

Identity: compare the type, serial number and condition with the order, datasheet and individual test record.

Performance: check frequency coverage, gain and output against the agreed acceptance criteria using the specified supply, cooling and test load.

Interfaces: inspect connectors, waveguide faces, mounting surfaces and electrical terminals for damage and compatibility with the intended equipment.

Packing: check that the tube is restrained, interfaces are protected and cushioning prevents movement; record transit damage before installation.

What goes wrong

A replacement can fit mechanically yet have the wrong frequency coverage, supply requirements or cooling arrangement. A headline output figure without test conditions can conceal performance that is unsuitable for the buyer's system. Refurbished tubes may also be supplied without an agreed condition statement or useful service history.

Make acceptance depend on the agreed operating conditions and traceable results. Check packing before dispatch and inspect on arrival before powering the tube. Use our quality inspection guide to set the inspection scope.

Cambridge China Bridge sources these products for UK businesses, checking the factory and the documents before shipment. See factory verification. For components and parts, see sourcing for manufacturers.