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2445B delayed By sweep


Ondrej Pavelka
 

Hi,

I'm wondering if what I'm seeing is normal or not. I had some narrow pulses wide apart to display, it was give or take 1kHz and spikes were some 20ns wide.

When I used the delayed B sweep I could only get rather faint B sweep intensity. When I turned the intensity readout and scale illumination low enough to be similar intensity to the B sweep the picture I obtained was quite good but it was in rather bright room with glares so it wasn't easy to read at all.
Is there some separate calibration setting which might have drifted or is it normal behaviour?


Roger Evans
 

Ondrej,

That sounds like perfectly normal behaviour. If you have a 100nsec display window for the B sweep and a 1kHz repetition rate then the beam is only turned on for 10^-8 sec every 10^-3 sec so one part in 10^5. You would see a similar intensity if you look at a 1kHz calibrator signal at 10nsec/div with just the A sweep but the 24x5 calibrators change their frequency with sweep speed.

Regards,

Roger


Ozan
 

Turning the hold-off control knob to "B ends A" position may improve brightness by not sweeping A trace after the point of interest.