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Zetagi CB amplifiers, 10m amplifiers and accessories, power supplies, microphones, SWR and power meters, battery charges manufacturers based in Italy. - Company out of business since 2024.

Conversion of Zetagi HP201 SWR wattmeter for HF Amateur Bands by G8ODE

Converting a ZETAGI B303 power amplifier for 50 MHz usage

The document provides a detailed modification guide for the Zetagi HP201 SWR Wattmeter, converting it for HF amateur band usage. It replaces the original circuit with a Tandem Coupler based on the Sontheimer and Frederick directional coupler patent, enhancing accuracy and sensitivity. Key components include Murata toroid cores, scaling resistors, and a new calibration process. Challenges and solutions during the modification process are discussed, ensuring linear results across 160-10m bands. This guide also includes calibration instructions and theoretical insights into the coupler's operation.