Figure 2-2. Transmitter spurious emissions for an AN/GRT-22.

TM 11-490-5

Figure 2-2. Transmitter spurious emissions for an AN/GRT-22.

(c)

Intermodulation and cross modulation.

connections and waveguide hardware, foreign material

inside waveguides, electron tubes whose operating

Intermodulation, the combining of RF signals in a

characteristics have changed through use, and changes

receiver front end or transmitter final stage, and cross

in circuit resistance or capacitance values as a result of

modultion, the superimposing of the modulation of an

overheating or aging, all of which illustrates the

undesired signal on a desired signal, occur as a result of

importance of preventive and corrective maintenance

circuit nonlinearities. A nonlinear circuit is one which

procedures.

An overdriven amplifier becomes a

does not pass or amplify all voltage levels or voltage

nonlinear device which clips or

polarities equally. Circuit nonlinearities may occur from

such simple causes as corroded or loose antenna

2-4