Author Topic: Riddle me this: ~1.8ns rise time on a Tek 2225???  (Read 1923 times)

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Offline slateraptor

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Riddle me this: ~1.8ns rise time on a Tek 2225???
« on: January 21, 2012, 01:24:31 am »
Sorry for the shit pic; old phone. :P

Anyways, just got a 2225 in the mail today and was doing a bit of playing around. The dual trace horizontal zoom function is quite nice (although fine adjust is a lot more finicky than I'd like it to be). Had to repair the cal port on the front panel too as it had somehow busted off on the main PCB end. After getting that done, I try to measure the cal signal rise time and got the attached pic...that's ~1.8ns. :o Significantly lower than I had anticipated.

Has anyone else with a 2225 encountered something similar?

Here's how I got there:
1) Compensated 10x probe on Ch1
2) Vertical at 100mV/div; vernier to scale
3) Horizontal at 0.1ms/div; switch to MAG view, select X50 (effectively 2ns/div); ensure hzn cal is locked
4) Trigger off falling edge; HF reject if no lock


P.S. If anyone has a digital copy of the 2225 service manual, please hook it up. :)

EDIT: I'm a dumbass. Disregard. More like 1.8us rise time for the cal signal...only off by 3 orders of magnitude. :-[
« Last Edit: January 21, 2012, 02:21:38 am by slateraptor »
 

Offline amspire

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Re: Riddle me this: ~1.8ns rise time on a Tek 2225???
« Reply #1 on: January 21, 2012, 02:06:19 am »
Isn't the maximum sweep speed of the 2225 5 nS/div, so that rise time is more like 4.5nS at best?

Looking at a picture of the front of a 2225, the x50 switch has the word "except" on it bracketting the 0.5, .1 and .2 uS/div speeds. In other words, you do not get a x50 MAG at 0.1uS/div.

Richard
 

Offline slateraptor

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Re: Riddle me this: ~1.8ns rise time on a Tek 2225???
« Reply #2 on: January 21, 2012, 02:13:12 am »
Isn't the maximum sweep speed of the 2225 5 nS/div, so that rise time is more like 4.5nS at best?

Looking at a picture of the front of a 2225, the x50 switch has the word "except" on it bracketting the 0.5, .1 and .2 uS/div speeds. In other words, you do not get a x50 MAG at 0.1uS/div.

Richard

Oops. I really meant 0.1ms, not micro; corrected in the first post.

EDIT: ...and that would explain my error in calculation. Doh!
 

Online BravoV

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Re: Riddle me this: ~1.8ns rise time on a Tek 2225???
« Reply #3 on: January 21, 2012, 02:23:00 am »
Quote from: slateraptor link=topic=6481.msg84806#msg84806

EDIT: I'm a dumbass. Disregard. More like 1.8us rise time for the cal signal...only off by an order of magnitude. :-[

Ha..ha.. don't worry, it happened once in a while, especially at scope without digital readout.  ;D

Anyway, congratz on the 2225 !


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