Sourcing klystron tubes from China

Klystron tube duty and classification

Read from the UK Trade Tariff on 2 October 2026, heading 8540 covers thermionic, cold cathode and photocathode valves and tubes. Klystrons fall within the other microwave tubes line, 8540 79 00 90, excluding grid-controlled tubes. The complete-tube rows describe different klystron types within that same commodity line, rather than separate tariff subdivisions.

The supplied tariff record shows 0% duty for goods from China under 8540 79 00 90 and the other tube parts line, 8540 99 00 90. Neither entry lists anti-dumping or countervailing duty, a suspension or an attached import control. Confirm that a separately supplied item qualifies as a tube part before using the parts code.

Give your broker the datasheet, function and supply description to confirm the commodity code. For the surrounding product family, see our vacuum tubes and magnetrons guide.

Specify the klystron and its operating conditions

State the equipment model, tube designation and whether the order is for a new or refurbished tube. Specify operating frequency, tuning range, continuous or pulsed operation, output power, gain where applicable, beam and heater supplies, cooling arrangements and mounting dimensions. Include drawings for the waveguide flange, electrical connections and coolant connections.

Agree acceptance tests at the intended operating conditions. Request results tied to the supplied tube's serial marking, with the test setup, cooling conditions and measured output recorded. Agree permitted substitutions before ordering; a claimed equivalent needs matching interfaces and operating requirements.

Official guidance treats component parts sold between businesses as outside the hazardous-substance regulations in their own right. Components used in an in-scope finished electrical product must nevertheless support that product's compliance. Request material declarations and identify any exemption relied on, as explained in our wider guide.

Worked duty example

Illustrative example, not a quote: A replacement klystron tube for an equipment repair business, illustrative only 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: check the designation, serial marking and declared new or refurbished condition against the order and individual test records.

Interfaces: compare mounting points, waveguide flange, connector layout and cooling connections with the approved drawing.

Performance: have a suitably equipped specialist check frequency, output and stability under the agreed supply and cooling conditions.

Packing: inspect the envelope, ceramic seals and connectors for damage; check supports prevent movement and protect projecting connections. Use our quality inspection guide to set the inspection brief.

What goes wrong

A replacement can match the headline frequency yet have incompatible mounting, cooling or supply requirements. A power figure without its operating conditions is difficult to compare. Refurbished stock supplied as new, mismatched test records and damage around seals or connectors are specific points to investigate.

Resolve discrepancies before shipment and retain the approved drawing and acceptance record for arrival checks. Agree who will investigate a tube that fails the equipment acceptance test, and what evidence they need.

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.