General The spectmm analyzer permits the detection of spectrum components of electrical signals in the frequency range of 0.15 to 1050 MHz for Models 2625 and 2630 and 0.15 to 500 MHz for Models 2615 and 2620. The detected signal and its content have to be repetitive, in contrast (o an oscilloscope operated in Yt mode, where the amplitude is displayed on the time domain, the spectrum analyzer displays amplitude on the frequency domain (YD. The individual spectrum components of “a signal" become visible on a spectrum analyzer. The oscilloscope would display the same signal as one resulting waveform, Models 2625 and 2630 The spectrum analyzer works according to the triple superhet receiver principle. The signal to be measured (fin = 0.15 MHz to 1050 MHz) is applied to the 1st mixer where it is mixed with the signal of a variable voltage controlled oscillator (fi.o 1350 MHz - 2350 MHz). This oscillator is called the 1st LO (locat oscillator). The diffcrence between the oscillator and the input frequency {fL.o - fus - 1st IF) is the first intermediate frequency, which passes through a waveband filter tuned to a center frequency of 1350 MHz. It then enters an amplifier, and this is followed by two additional mixing stages, oscillators and amplifiers. The second IF is 29.875 MHz and the third is 2.75 MHz. In the third IF stage, the signal can be selectively transferred through a filter with 400 kHz or 20 kHz bandwidth before arriving a! an AM demodulator. The logarithmic ompuu video signal) is transferred directly, or via a low pass filter to another ampiifier. This amplifier output is connected to the Y deflection plates of the CRT. Models 2615A and 2620A The spectmm analyzer works according to the tnpie superhet receiver principle. The signal to be measured (fm = 0.5 MHz to 500 MHz) is applied to the 1st mixer where it is mixed with the signal of a variable voltage controlled oscillator (ft.o6!0 MHz - 1 1 10 MHz). This oscillator is called the 1st LO (local oscillator). The difference between the oscillator and the input frequency (ft.o - f>n = 1st IF) is the first intermediate frequency, which passes through a waveband filter tuned to a center frequency of 609.5 MHz. it then enters an amplifier, and this is followed by two additional mixing stages, oscillators and amplifiers. The second IF is 29.5 MHz and the third is 2.9 MHz. in the third IF stage, the signal can be selectively transferred through a filter with 250 kHz or 20 kHz bandwidth before arriving at an AM demodulator. The logarithmic output (video signal) is transferred directly, or via a low pass filter to another amplifier. This amplifier output is connected to the Y deflection plates of the CRT. The X deflection is performed with a ramp generator voltage. This voltage can also be superimposed on a dc voltage which allows for the control of 1st LO. The spectrum analyzer scans a frequency range depending on the ramp height. This span is determined by the scan width setting. In ZERO SCAN mode only the direct voltage controls the 1st LO. Models 2620A and 2630 each include a tracking generator. This generator provides sine wave voltages within the frequency range of 0.! to 1050 MHz for Model 2630 and 0. i to 500 MHz for Model 2620A. The tracking generator frequency is determined by the first oscillator (1st LO) of the spectrum analyzer section. Spectrum analyzer and tracking generator are frequency synchronized.