EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: lucasc on July 21, 2020, 01:31:56 pm
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Hello everyone,
I have recently purchased a used Tektronix 11801 and I was getting acquainted and running some basic validation tests on it to make sure everything is working fairly well.
So far everything seems to be fine with exception of one thing, I noticed that the noise in the signal gets significantly larger as a move the display "Main Pos" father from the trigger point. To be very clear, this "Main Pos" parameter moves the X-axis of the signal in relation to the trigger, so if the trigger happened at time = 0, and the Main Pos is set to 49ns, that means that the oscilloscope is starting to capturing and show the signal 49ns after every trigger.
My understanding is that I should be able to move far away from the trigger without compromising the signal quality, but it seems that this is not happening right now. The attached pictures show a comparison between when I capture the edge as close as possible to the trigger, and another waveform where I intentionally wait for about 11us to capture the waveform.
It's very clear that the more I wait to capture the more noise it gets and I believe this is due to jitter either on the scope of on the signal source. Now I'm concerned that this could be an issue with the scope, but I'm not sure if:
1. This is the expected behavior of the 11801
2. My signal source is jittery and that is why the farther I am from the trigger, the higher the jitter.
The waveforms attached were taken with the Leo Bodnar edge generator (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295 (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295)) and I also tried with the scope internal clock output signal; the same thing happened.
Can anyone that uses this scope tell me if you see the same behavior?
Thanks in advance,
Lucas