Gain, noise, and the 5 V ceiling
The BFP420H6801XTSA1: With a collector-emitter breakdown of 5 V and a max collector current of 35 mA, this transistor is designed for low-voltage RF stages — think battery-powered or regulated 3.3 V / 5 V front-ends where the supply rail is tight. The 21 dB gain at 1.8 GHz means a single stage can lift a weak signal from an antenna or SAW filter to a level the mixer or LNA input can work with, without needing a second gain block. The 1.1 dB noise figure at 1.8 GHz is the spec that decides fit for a receiver input: a lower noise figure here directly improves the cascaded system NF. The 60 minimum DC current gain at 20 mA, 4 V confirms the transistor has enough beta to bias cleanly in a common-emitter stage without excessive base current loading the bias network.
SC-82A SOT-343 — field-swap reality
The SC-82A (SOT-343) package is a standard 4-pin surface-mount footprint, 1.25 mm pitch on the collector/emitter side.
RoHS3 and temp rating
ROHS3 compliant and rated for a 150 °C junction temperature — this transistor handles the self-heating from 160 mW dissipation in a small package without derating down to an 85 °C ambient. No special storage or handling beyond standard MSL precautions.