Author Topic: Scope rising time  (Read 41269 times)

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Offline tinhead

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Re: Scope rising time
« Reply #50 on: April 25, 2011, 02:38:59 pm »
Can somone explain why the switcher as this weird "3 diodes" configuration ?

actually voltage doubler/pump
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Offline jahonen

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Re: Scope rising time
« Reply #51 on: April 26, 2011, 02:09:06 pm »
Ok, here are the results with a 6 GHz scope, with RG-174 charge line and without for comparison. Didn't test the ribbon cable, though. Slew rate of the signal is also shown (20 V/ns scale), so that it can be seen if volts/time unit figure is changed. It seems that attaching the RG-174 cable does not degrade the edge, although the rise time figure seems to be quite mediocre, maybe I should try a different transistor specimen.

And I almost forgot, thanks to Leo Bodnar pointing out this trick, otherwise I wouldn't have bothered to check this as charge line implementation in LTC AN-94 is slightly different. I have some Suhner sucotest cables which are spec'ed up to 18 GHz or so and would like to know how they would work as a charge line, but I am reluctant to butch those just for curiosity :)

« Last Edit: April 26, 2011, 02:11:31 pm by jahonen »

Offline vk6zgo

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Re: Scope rising time
« Reply #52 on: April 28, 2011, 04:10:04 am »
All of the above brings to mind the TU-5 Pulser,which was an accessory for the Tektronix 545B .

This device used a Tunnel diode to create the sharp risetime.

In use,it was driven from the 545B calibrator,which was set to 90v,if I remember

The calibration signal caused the Tunnel diode to breakdown after a set voltage level,producing a fast  risetime for the part of the rise above that voltage.

In use, 10% to 90% of this section was used to measure rise time.

I had one,but it wasn't much use without the  high level calibration voltage,so I gave it away to a friend who was collecting 545s & their accessories.


Offline tnt

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Re: Scope rising time
« Reply #53 on: May 03, 2011, 07:28:51 pm »
Interesting, with my 350MHz Agilent DSO-X 3000, I get 900 ps rise time just measuring a clock signal ...


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