What are the principal frequencies that appear at the output of a mixer?
The correct answer is C: The two input frequencies along with their sum and difference frequencies. What are the principal frequencies that appear at the output of a mixer are the two input frequencies along with their sum and difference frequencies. Mixers produce sum and difference frequencies. For amateur radio operators, this is important for mixer theory. Understanding this helps when working with mixers.
Exam Tip
Principal frequencies at mixer output = two input frequencies + sum and difference frequencies. Think 'M'ixer = 'M'ixes frequencies (sum and difference). Mixers produce sum and difference frequencies. Not 2x/4x, not square root, not 1.414/0.707 - just input frequencies + sum and difference.
Memory Aid
"Principal frequencies at mixer output = two input frequencies + sum and difference frequencies. Think 'M'ixer = 'S'um and 'D'ifference. Mixers produce sum and difference frequencies. Important for mixer theory."
Real-World Application
The principal frequencies at the output of a mixer: They are the two input frequencies along with their sum and difference frequencies. For example, if inputs are f1 and f2, outputs include f1, f2, f1+f2, and f1-f2. This is what appears - input frequencies + sum and difference.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Two and four times input frequency isn't correct - mixer produces sum and difference frequencies. 2x and 4x isn't correct.
Option B: Incorrect. Square root of product of input frequencies isn't correct - mixer produces sum and difference frequencies. Square root isn't correct.
Option D: Incorrect. 1.414 and 0.707 times input frequency isn't correct - mixer produces sum and difference frequencies. 1.414/0.707 isn't correct.
题目解析
The correct answer is C: The two input frequencies along with their sum and difference frequencies. What are the principal frequencies that appear at the output of a mixer are the two input frequencies along with their sum and difference frequencies. Mixers produce sum and difference frequencies. For amateur radio operators, this is important for mixer theory. Understanding this helps when working with mixers.
考试技巧
Principal frequencies at mixer output = two input frequencies + sum and difference frequencies. Think 'M'ixer = 'M'ixes frequencies (sum and difference). Mixers produce sum and difference frequencies. Not 2x/4x, not square root, not 1.414/0.707 - just input frequencies + sum and difference.
记忆口诀
Principal frequencies at mixer output = two input frequencies + sum and difference frequencies. Think 'M'ixer = 'S'um and 'D'ifference. Mixers produce sum and difference frequencies. Important for mixer theory.
实际应用示例
The principal frequencies at the output of a mixer: They are the two input frequencies along with their sum and difference frequencies. For example, if inputs are f1 and f2, outputs include f1, f2, f1+f2, and f1-f2. This is what appears - input frequencies + sum and difference.
错误选项分析
Option A: Incorrect. Two and four times input frequency isn't correct - mixer produces sum and difference frequencies. 2x and 4x isn't correct. Option B: Incorrect. Square root of product of input frequencies isn't correct - mixer produces sum and difference frequencies. Square root isn't correct. Option D: Incorrect. 1.414 and 0.707 times input frequency isn't correct - mixer produces sum and difference frequencies. 1.414/0.707 isn't correct.
知识点
Principal frequencies, Output of mixer, Two input frequencies, Sum and difference frequencies
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.