The Bird Model 4431 is a portable, analog wattmeter based on the trusted Model 43-enhanced with an integrated RF signal sampling port. It provides average power measurement using Bird’s interchangeable plug-in elements, while also offering a low-power sampled output via a BNC connector.

This lets technicians monitor frequency, modulation, or harmonics using external equipment without disturbing the signal path. Ideal for lab work, tuning, and system verification.