FCC Exam Question: 6A322

The most common values of chokes range from:

A. 5 H to 30 H
B. 30 H-100 H
C. 1 H to 100 H
D. 100 H to 1000 H
Correct Answer: A

Explanation: Chokes, or inductors, are commonly used in power supply filters to smooth out pulsating DC current by opposing changes in current flow. Their effectiveness in filtering ripple voltage is directly related to their inductance value, among other factors like the ripple frequency. A range of **5 H to 30 H** strikes a practical balance between effective filtering and physical size, weight, and DC resistance (DCR). Lower values like 1 H typically require very large capacitance to achieve adequate filtering, while much higher values (e.g., 100 H or more) become prohibitively large, heavy, costly, and introduce significant voltage drop and power loss due to their increased DCR. This makes the 5-30 H range the most common choice for general-purpose filtering in many amateur radio power supplies, especially in classic designs.

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Includes Elements 1, 3, 6, 7R, 8, and 9.