8540.81.00.00 - Receiver or amplifier tubes

This HTS category, 8540.81.00.00, specifically covers receiver or amplifier tubes. These are thermionic, cold cathode, or photocathode tubes designed primarily for receiving or amplifying electronic signals. This includes a wide range of vacuum tubes and gas-filled tubes that perform these specific functions, excluding those with other primary purposes.

This classification is distinct from its sibling, 8540.89.00, which encompasses "Other" tubes within the broader heading of thermionic, cold cathode, or photocathode tubes. While 8540.81.00.00 is focused on the signal reception and amplification function, the "Other" category would capture tubes designed for different primary applications, such as display devices, high-power transmission, or specialized scientific instrumentation, where signal reception or amplification is not their principal role.

As this is a leaf node within the HTS structure, there are no further subcategories. Therefore, classification within 8540.81.00.00 relies on accurately identifying the tube's core function as either signal reception or amplification, based on its design and intended use.