Subelement A: — Topic :
Question 6A468
Element 6 (Radiotelegraph)A superheterodyne receiver is adjusted to 2738 kHz. The IF is 475 kHz. What is the grid circuit of thesecond detector tuned to?
Explanation
In a superheterodyne receiver, the incoming radio frequency (RF) signal is mixed with a local oscillator (LO) signal to produce a fixed Intermediate Frequency (IF) signal. This IF signal is then amplified by the IF amplifier stages, which are always tuned to this specific IF frequency, regardless of the original RF frequency.
The second detector's purpose is to extract the intelligence (audio, data, etc.) from this amplified IF signal. To do this efficiently, its input circuit (the grid circuit in a tube-based receiver, or equivalent input in a solid-state design) must be tuned to the IF frequency. Therefore, it will always be tuned to 475 kHz. The other options represent either the original RF signal, possible local oscillator frequencies, or harmonics, none of which are directly applied to the second detector for demodulation.
Related Questions
6A466 What is the "mixer" tube in the superheterodyne receiver?6A467 An incoming signal causing image interference is ____ the IF above or below the frequency to which thereceiver is tuned:6A469 A superheterodyne receiver may not successfully be used for reception of frequencies very near the IFfrequency:6A47 The difference between electrical power and electrical energy is:6A470 Some superheterodyne receives employ a crystal-controlled oscillator: