Deep Dive: E4D05
The correct answer is A: 146.34 MHz and 146.61 MHz. What transmitter frequencies would create an intermodulation-product signal in a receiver tuned to 146.70 MHz when a nearby station transmits on 146.52 MHz is 146.34 MHz and 146.61 MHz. IMD products: 2×146.52 - 146.34 = 146.70, or 146.61 + 146.52 - 146.34 = 146.79 (close). For amateur radio operators, this is important for understanding IMD. Understanding this helps when troubleshooting interference.
Why Other Answers Are Wrong
Option B: Incorrect. 146.88 MHz and 146.34 MHz doesn't create 146.70 MHz IMD - 146.34 MHz and 146.61 MHz does. 146.88/146.34 isn't correct. Option C: Incorrect. 146.10 MHz and 147.30 MHz doesn't create 146.70 MHz IMD - 146.34 MHz and 146.61 MHz does. 146.10/147.30 isn't correct. Option D: Incorrect. 146.30 MHz and 146.90 MHz doesn't create 146.70 MHz IMD - 146.34 MHz and 146.61 MHz does. 146.30/146.90 isn't correct.
Exam Tip
IMD frequencies creating 146.70 MHz with 146.52 MHz = 146.34 MHz and 146.61 MHz. Think 'I'MD = 'I'nterference 'M'ixing 'D'istortion. IMD products: 2×146.52 - 146.34 = 146.70. Not 146.88/146.34, not 146.10/147.30, not 146.30/146.90 - just 146.34 and 146.61 MHz.
Memory Aid
IMD frequencies creating 146.70 MHz with 146.52 MHz = 146.34 MHz and 146.61 MHz. Think 'I'MD = '1'46.34 and '1'46.61. IMD products: 2×146.52 - 146.34 = 146.70. Important for understanding IMD.
Real-World Example
A receiver tuned to 146.70 MHz with a nearby station on 146.52 MHz: Transmitter frequencies of 146.34 MHz and 146.61 MHz would create intermodulation-product signals. For example, 2×146.52 - 146.34 = 146.70 MHz. This is the combination - 146.34 MHz and 146.61 MHz.
Source & Coverage
Question Pool: 2024-2028 Question Pool
Subelement: E4D
Reference: 2024-2028 Question Pool · E4 - Amateur Practices
Key Concepts
Verified Content
Question from the official FCC Extra Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the E4D topic.