Step Attenuator suitable for 0 - 30MHz
Build a 0-30 MHz step attenuator for receiver sensitivity evaluation and S-meter calibration
Description
A 0-30 MHz step attenuator, constructed from switchable Pi attenuation pads, provides a practical tool for evaluating receiver sensitivity and calibrating S-meters. The design utilizes readily available 5% tolerance resistors, with values derived from paralleled components to achieve specific attenuation steps. A schematic (Fig 1) illustrates the circuit, including PCB pad shielding, while a table details required and actual resistor values, along with percentage differences.
Measurements of voltage input versus output at various frequencies are used to calculate dB attenuation, presented in a graph (Fig 4). The resource includes formulas for determining output voltage from a known input and a comprehensive 0-40 dB voltage multiplier table, which is crucial for precise signal level management. The project also references external attenuator calculators and equations for further study.
Photos (1-3) provide visual guidance for the assembled unit, showing bottom, top, and front views. The project emphasizes the use of Pi attenuation pads and receiver sensitivity evaluation, offering a hands-on approach to RF signal management.