This video shows how to measure the input impedance and gain of a small-signal RF amplifier - including the use of an attenuator to keep the amp in it's linear range and also to not overdrive the NanoVNA. This stems from a recent conversation with Bill N0CQR (SolderSmoke podcast). The amplifier featured is a "Termination Insensitive Amplifier" or TIA that is described in paper by Wes Hayward (W7ZOI) and Bob Kopski (K3NHI) - see links below:
Soldersmoke blog:
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Wes's webpage: [ Ссылка ]
The TIA paper: [ Ссылка ]
Papers on the theory and models of transistor amps:
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