Where must frequency-determining elements be located within the transceiver?

The frequency-determining elements must be located within the transceiver because these components are crucial for the accurate generation and modulation of radio frequencies. The design of a transceiver integrates these elements to ensure optimal performance, stability, and reliability in signal transmission and reception. By placing these elements internally, manufacturers can better shield them from external interference and environmental factors that might disrupt frequency stability. This arrangement also allows for more efficient signal processing and quality control, as the transceiver can be optimized as a complete unit.

Locating frequency-determining elements elsewhere, such as next to the power source or on the aircraft exterior, would expose them to potential interference and could compromise the overall functionality and performance of the communication system. Additionally, placing them in the pilot's headset would not only be impractical but also fail to meet the design requirements for radio communication systems, which necessitate that these elements be part of the transceiver architecture.