Sourcing vacuum pentode tubes from China

0% duty on receiver and amplifier pentodes

Read from the UK Trade Tariff on 2 October 2026, heading 8540 covers thermionic, cold cathode and photocathode valves and tubes. Vacuum pentodes used as receiver or amplifier valves fall within the receiver or amplifier line, 8540 81 00 90. The table shows buying formats sharing this line, rather than separate tariff classifications.

The supplied snapshot records 0% duty for goods from China. It lists no anti-dumping or countervailing measures, suspensions or attached import controls for this line. Import VAT is separate from customs duty; see UK import duty and VAT.

Confirm the commodity code using the tube datasheet and intended function, especially for specialised tubes or separate parts. For related products within the wider heading, see power tetrode tubes.

Specify pentode ratings and matching conditions

State the exact type, accepted equivalents, base and pin connections, envelope dimensions, heater voltage and current, anode and screen-grid ratings, and intended circuit. Agree the test circuit, operating point, burn-in procedure and acceptance criteria. For matched sets, specify which readings are matched and require results traceable to each tube.

For Great Britain, official guidance states that component parts sold between businesses are outside the hazardous-substance regulations. Confirm with the relevant authority which requirements apply to the finished assembly. Ask for material evidence and details of any exemption relied on, as our published valve guide recommends. Agree whether the supply is for incorporation into equipment or sale as replacement stock; discuss compliance evidence with our testing and certification service.

Worked duty example

Illustrative example, not a quote: Illustrative order: 300 amplifier pentodes for a repair business under 8540 81 00 90, invoiced at £5,000 free on board, with £600 of freight and insurance to the UK. The customs value is £5,600. Duty at 0% is £0. Import VAT at 20% is charged on the customs value plus duty, £5,600, so it is £1,120. 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, base, pin connections and dimensions with the approved sample and datasheet; check batch traceability.

Electrical performance: test emission, transconductance, leakage, noise and microphonics under the agreed conditions; compare matched-set results after burn-in.

Glass and pins: inspect for cracks, loose bases, bent pins and changes in getter appearance that may indicate loss of vacuum.

Packing: check individual cushioned boxes, separation between tubes and protection against pin damage. Record arrival damage before unpacking the whole batch; use the quality inspection guide.

What goes wrong

A matching label is insufficient without readings taken under agreed conditions. Tubes can appear matched on a supplier's tester yet behave differently in the buyer's circuit. Noise, microphonics and early heater failure can remain hidden until operating tests. Relabelled types can also conceal different ratings or pin connections.

Approve samples in the intended circuit before accepting bulk production. Keep tube identities linked to test records and matched sets together through packing. Quarantine cracked envelopes, suspect vacuum loss and unstable readings, and agree replacement evidence with the supplier.

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.