A signal generator produces a controlled output waveform and classifies under 854320, while an oscilloscope (which measures and displays input signals) and a spectrum analyzer (which analyzes frequency content of input signals) are measuring instruments that classify under Chapter 90. Combination instruments — such as a vector network analyzer that both generates and measures signals — require classification based on the essential character of the device, typically guided by CBP rulings and the HS Explanatory Notes for Chapter 85 versus Chapter 90.

Yes. Advanced signal generators capable of generating signals at microwave or millimeter-wave frequencies, or with high output power and modulation sophistication, may be classified as dual-use test equipment under the EAR with specific ECCN designations. Re-export to certain countries or end users — particularly those with military or proliferation concerns — may require a BIS export license. Importers and distributors should review the EAR classification of each model before any re-export or deemed export to foreign nationals.