General LSG-231 is specially designed for use in testing FM stereo and monaural receivers and stereo multiplex circuits. The composite signals for the subchannel, main channel, left and right channels at 1kHz are generated in the stereo modulation section. The 38kHz subcarrier and 19kHz pilot signal are produced by stepping down the frequencies from a 228kHz crystal-controlled oscillator. The composite signal is generated by switching two balanced diode modulators with the subcarrier signal. A lowpass filter is used to suppress undesirable spurious components. The pilot signal is added to the stereo signal in the composite amplifier. The composite signal is available directly for stereo MPX testing or for frequency modulation of the RF oscillator. Inputs are provided for external stereo modulation with preemphasis at 75jis or 5ÛJJS. Testing is possible for the SCA circuit with use of the internal 67kHz signal or external input. FEATURES: 1. Over 50dB left-right channel separation at 1kHz. for critical separation tests- 2. Phased condition of the pilot and subcarrier signals is of the highest degree. 3. Modulated RF output for simulation of FM broadcasts signals used in overall receiver testing. 4. Pilot signal level can be adjusted in the range, 0 to over 10%, independently of the composite signal. 5. Composite signal can be adjusted in the range, 0 to 100%, independently of the pilot signal level. 6. High reliability components, including integrated circuits are used for stable operation.