[AMRadio] Be carefull with your scope!

[Phil (VA3UX)]

That really is a good reminder Mark. A few weeks ago I was reading mail on 
a guitar amp list that I'm on and one of the guys was talking about 
measuring B+ ripple with a scope on his 550V supply. The scope input 
voltage rating thing occured to me so I mentioned on the list to be sure 
the scope input and probe were rated for that voltage. The response was 
like a deer staring into the headlights : "Huh? Theres a voltage rating on 
this stuff ? ". Well he did know there was but he hadn't used his scope for 
a couple of years and he had competley forgotten about it.  No damage was 
done but he was lucky.

It's one thing to toast an old $50 service grade scope but it's a different 
thing to hurt an HP 17xx series scope. "Needs repair" scopes in the HP 1700 
series come up for auction quite often on eBay. If you can't get the parts, 
consider buying a parts unit.

Thanks

Phil

At 10:22 PM 2/18/2002 -0500, you wrote:
>Just a word of warning from someone that learned a lesson the hard way.
>I was working on my Apache with my 275Mhz HP scope and after many
>years of working on solid state gear, forgot that the scope has a Max.
>input voltage limit. I totally trashed one input channel on a scope that was
>
>working well! Sure had a long talk with myself after that!
>
>Hope this may help others avoid this pitfall!
>
>Mark W1MJG
>
>
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