What combination of a mixer’s Local Oscillator (LO) and RF input frequencies is found in the output?
The correct answer is C: The sum and difference. The combination of a mixer's Local Oscillator (LO) and RF input frequencies found in the output is the sum and difference. Mixers produce sum (LO + RF) and difference (LO - RF) frequencies. For amateur radio operators, this is fundamental mixer operation. Understanding this helps when working with mixers.
Exam Tip
Mixer output = sum and difference of LO and RF. Think 'M'ixer = 'M'ixes to produce 'S'um and 'D'ifference. Mixers produce sum (LO + RF) and difference (LO - RF) frequencies. Not ratio, not average, not product - just sum and difference.
Memory Aid
"Mixer output = sum and difference of LO and RF. Think 'M'ixer = 'M'ixes to produce 'S'um and 'D'ifference. Mixers produce sum (LO + RF) and difference (LO - RF) frequencies. Fundamental mixer operation."
Real-World Application
A mixer: LO = 14.655 MHz, RF = 14.200 MHz. Output contains: Sum = 14.655 + 14.200 = 28.855 MHz, Difference = 14.655 - 14.200 = 0.455 MHz (IF). Mixers always produce sum and difference frequencies. The difference frequency (IF) is typically used in receivers. This is fundamental mixer operation.
Key Concepts
Why Other Options Are Wrong
Option A (The ratio): Incorrect. Mixers don't produce the ratio - they produce sum and difference frequencies, not ratios. Ratio isn't the output.
Option B (The average): Incorrect. Mixers don't produce the average - they produce sum and difference frequencies, not averages. Average isn't the output.
Option D (The arithmetic product): Incorrect. Mixers don't produce the arithmetic product - they produce sum and difference frequencies, not products. Arithmetic product isn't the output.
题目解析
The correct answer is C: The sum and difference. The combination of a mixer's Local Oscillator (LO) and RF input frequencies found in the output is the sum and difference. Mixers produce sum (LO + RF) and difference (LO - RF) frequencies. For amateur radio operators, this is fundamental mixer operation. Understanding this helps when working with mixers.
考试技巧
Mixer output = sum and difference of LO and RF. Think 'M'ixer = 'M'ixes to produce 'S'um and 'D'ifference. Mixers produce sum (LO + RF) and difference (LO - RF) frequencies. Not ratio, not average, not product - just sum and difference.
记忆口诀
Mixer output = sum and difference of LO and RF. Think 'M'ixer = 'M'ixes to produce 'S'um and 'D'ifference. Mixers produce sum (LO + RF) and difference (LO - RF) frequencies. Fundamental mixer operation.
实际应用示例
A mixer: LO = 14.655 MHz, RF = 14.200 MHz. Output contains: Sum = 14.655 + 14.200 = 28.855 MHz, Difference = 14.655 - 14.200 = 0.455 MHz (IF). Mixers always produce sum and difference frequencies. The difference frequency (IF) is typically used in receivers. This is fundamental mixer operation.
错误选项分析
Option A (The ratio): Incorrect. Mixers don't produce the ratio - they produce sum and difference frequencies, not ratios. Ratio isn't the output. Option B (The average): Incorrect. Mixers don't produce the average - they produce sum and difference frequencies, not averages. Average isn't the output. Option D (The arithmetic product): Incorrect. Mixers don't produce the arithmetic product - they produce sum and difference frequencies, not products. Arithmetic product isn't the output.
知识点
Mixer output, Local oscillator, RF input, Sum and difference
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.