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Figure 3-8.Radio transmitter unit.
ANTENNA DISTRIBUTION SYSTEMS

Neets Module 17-Radio-Frequency Communications Principles
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3-10 Figure 3-9.—Typical radio transmitting set block diagram. RECEIVERS The receiver we will discuss is a triple-conversion superheterodyne, tunable from 2 to 30 megahertz. Triple conversion uses three IF frequencies to give better adjacent-channel selectivity and greater image- frequency suppression. Figure 3-10 shows the front panel of this receiver where tuning is done digitally by five controls and a switch. A display window directly above each control provides a digital readout of the frequency setting. The displayed frequency can be changed in 1-kilohertz increments. The front panel switch allows the operating frequency to be changed in 100- or 500-hertz increments depending on the model. This will provide you with 280,000 discrete frequencies locked to a very accurate frequency standard. You can continuously tune each 1,000-hertz increment by selecting the VERNIER position of the hertz switch. When using the vernier, the full accuracy of the frequency standard is sacrificed. The receiver demodulates and provides audio outputs for the lsb, usb, isb, AM, cw, and fsk types of received signals.






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