Hi, I have a Tektronix 7704A oscilloscope with both a 7B80 time base and a
7B53A dual time base. The 7B53A dual time base plugs into a slot labeled "A horiz (delaying time base). What is the dual time base used for? I really don't want to use it, for now, and I'd like to not worry about setting it up or having it influence measurements.Thanks -Ira
A delayed sweep function is used for viewing short duration events on signals with long periods. For example, you want to observe a single low amplitude noise pulse out of many that occur somewhere in the middle of a high amplitude periodic signal. If you trigger on the main signal, you can't see the details of the noise pulse. You could try using AC coupled triggering to trigger on the noise pulse, but you can't control which of the noise pulses the 'scope will trigger on. Enter the delayed sweep 'scope: You set up the delayed sweep timebase (the one in the right hand slot) such that its sweep frequency is appropriate for viewing the noise pulse. The delaying time base allows you to delay the triggering of the delayed sweep by an amount equal to the time between the trigger point of the main signal and the time at which the noise pulse occurs. At that time, the delayed sweep triggers, allowing the noise pulse to be observed at a fast sweep rate on the 2nd channel of the 'scope. The portion of the waveform that is viewable by the delayed sweep is displayed as an enhanced brightness on the trace. By adjusting the delay time knob, you can move this enhanced brighness traces back and forth until it spans the noise pulse. By not selecting the delayed sweep feature, you can use the 'scope as a normal 'scope..
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