Sourcing power tetrode tubes from China

UK duty on power tetrode tubes

Read from the UK Trade Tariff on 2 October 2026, heading 8540 covers thermionic, cold cathode and photocathode valves and tubes. The supplied receiver or amplifier tube line, 8540 81 00 90, carries 0% duty for goods from China. The supplied facts list no anti-dumping or countervailing duty, suspensions or attached import controls.

The table repeats the amplifier tube line for different buying specifications, rather than presenting separate tariff lines. Confirm the commodity code against the tube's datasheet and intended function. For related tubes within the wider heading, see the power triode vacuum tube guide.

Specify screen-grid ratings and cooling

State the manufacturer's type designation and approved equivalents. Specify filament voltage and current, anode and screen-grid ratings, control-grid bias, operating frequency and intended duty. Request the connection diagram, envelope dimensions, mounting details and cooling requirements. Have the equipment engineer approve substitutions before ordering.

For matched tubes, agree the test circuit, operating conditions and acceptance limits. Request individual results for anode current, screen-grid current and transconductance, with agreed burn-in records. Matching results taken under different conditions are difficult to compare.

In Great Britain, electrical and electronic equipment, cables and spare parts fall within restricted-substance rules unless specifically excluded. For tubes incorporated into covered equipment, request material declarations and evidence for any claimed exemption so the finished product can meet those rules.

Worked duty example

Illustrative example, not a quote: Illustrative batch of replacement power tetrode amplifier tubes under 8540 81 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 type markings, batch records, connection diagrams and dimensions with the approved sample and order.

Electrical: have qualified personnel check filament continuity, electrode shorts, leakage and agreed operating results using a suitable protected test rig.

Envelope and cooling: inspect glass or ceramic for cracks, seals for damage, contacts for distortion and cooling surfaces for obstruction.

Packing: check individual supports protect the envelope and contacts, prevent movement and keep the tube clear of loads from neighbouring cartons.

What goes wrong

A replacement can fit its socket while having incompatible screen-grid ratings or cooling needs. Relabelled tubes, inconsistent emission and matching without comparable test records also cause disputes. Treat an equivalent-type claim as a proposal for engineering approval.

Transport damage can leave cracked envelopes or bent contacts. Photograph packing and damage before unpacking the batch, and separate suspect tubes pending assessment. Agree the inspection method and acceptance criteria before dispatch using the quality inspection guide.

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.