Question 50G4

Analog meters, including RF wattmeters, are generally most accurate and provide the best resolution in the upper portion of their scale. At the lower end, the needle deflection is small, making precise reading difficult due to scale compression and potential parallax error. More importantly, any inherent absolute error in the meter movement (due to friction, non-linearity, or component tolerance) represents a much larger *percentage* of a small reading than it does for a larger reading towards full scale. Therefore, readings are more reliable and precise when the needle is deflected into the upper one-third, maximizing the signal-to-noise ratio of the measurement against the meter's inherent uncertainties. Accuracy is not uniform, nor is it best in the lower or middle portions.