Pulse Modulation Video Feedthrough - Agilent Technologies 83620A Service Manual

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15. Pulse Modulation Video Feedthrough

Description and Procedure
In CW, at speci ed maximum leveled power, the synthesizer is pulse modulated
using a pulse generator. he synthesizer's RF output is ltered (only the video
feedthrough passes), ampli ed, and displayed on an oscilloscope. Because of
the low amplitude of the video feedthrough, a preampli er is used in the test
setup; system gain must be considered when making this measurement.
When video feedthrough is expressed as a percentage, the following equation is
used:
Video feedthrough (%) = [(video Vp/carrier Vp) x 100]/video gain
1. Preset all the instruments shown in Figure 2-21 and let them warm up for
at least one hour.
2. o achieve peak power, turn on RF peaking:
Tracking Menu Peak RF Always
USER CAL
5
3. Connect the equipment as shown in Figure 2-21 with the pulse generator
connected directly to channel 1 of the oscilloscope (A).
HP 8360
(asterisk on)
Performance Tests
Pulse Modulation Video Feedthrough
2-87