The Model 43P has the Bird 4300-400 peak reading conversion kit installed. The Model 4300-400 kit is
designed to easily convert any Model 43 to accurately read peak power in AM, SSB
and certain limited pulse applications. Installation of the kit in no way
affects the Model 43’s ability to accurately read CW power. The circuitry
operates from 2 standard 9V alkaline batteries.
Bird Model APM-16 Wattmeter
The Model APM-16 RF wattmeter is designed to keep pace with the ever growing complexity of digitally-based communication systems. Bird's Model 43 and most other wattcmeters available today were designed to measure power of constant amplitude, sinusoidal waveforms. Modern wireless communication systems can use a variety of digital techniques to combine many voice data channels into a complex, composite RF signal. Measurement of such signals with a conventional wattmeter may yield unacceptable errors. The APM-16 employs active circuitry to deliver accuracy of ± 5% for multiple-access technologies such as CDMA, TDMA, FDMA and other digitally-encoded communication systems.