O'scopes - Tek vs HP/Agilent vs LeCroy

Dec 14, 2006 61 Replies

I don't think so. The monitor switches scan frequency when going from Windows to DOS. There is something in the monitor that creates extra noise when scrolling. There is no noise on a static display.

There is nothing in the cable that knows what scan rate the monitor is using at the moment. The blips do not occur at 1024X768, only at 640X480.

However, moving to a 5/8 wave vertical completely solved the problem. There is no more noise on any frequency through the entire FM band, even though the vertical is only a foot from the monitor.

This problem has plagued me for several years, and this is the first time I found something that worked. Than you very much for mentioning EMI in an earlier post. For some reason that triggered the idea to try a different approach - and it worked!

That doesn't help when switching cards or checking for lint buildup. Or discovering the cpu fan is seizing and ready to fail.

Obviously, if you are in an environment where screwdrivers, paper clips, solder balls and coffee is flying through the air, you need some protection for your computers. But I have a very benign environment. I have no visitors to worry about, and everything is open the way I like. The covers on computers just slow me down and impede creativity. And that's a sin.

Do you know how difficult it is to replace the covers on a computer after fixing it? I just spent 1/2 hr fooling with the covers on my landlord's computer. What a pain. I'll leave mine off, thank you very much:)

I do have a fan salvaged from the freezer section in a fridge that mounts on the side of the computer during warm spells. It runs very quiet and helps reduce crashes on hot days. But obviously it's time to upgrade all the computers in the lab. And part of the new spec will be reliable operation at elevated temperature:)

Regards,

Mike Monett

Antiviral, Antibacterial Silver Solution:

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SPICE Analysis of Crystal Oscillators:
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Noise-Rejecting Wideband Sampler:
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I had that problem and found that securing the case solved it. There's nothing the monitor does differently when displaying a scrolling or static image that's likely to cause radiated noise... OTOH all the updates going over the expansion bus will radiate during scrolling. and there could easily be 4000 active bus cycles per line scrolled.

the punched cases are effectively see-through, but yeah you still have to open them, takes anout 2 minutes to move the cables out of the way, undo the 2 thumbscrews and slide the panel back a little to disengage it.

yeah, some are like that.

Bye. Jasen

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