| Equipment | Role | Homemade Alternative | |-----------|------|----------------------| | Signal generator | Source for stimulus | Vackář oscillator + step attenuator | | Spectrum analyzer | Observe frequency domain | Simple diode detector + oscilloscope (limited) | | Return loss bridge | Impedance & SWR measurements | Homemade resistive bridge (e.g., 3-resistor design) | | Power meter | Absolute power levels | Schottky diode detector + calibration | | Frequency counter | Precise frequency | Use receiver with known frequency reference |