FreeLists / si-list / [SI-LIST] Re: Scope probe attenuation

["Degerstrom, Michael J." <degerstrom.michael@xxxxxxxx>]

David's answer is more concise than the one I just 
posted.  The probe manufacturer should (and probably
does) add in the 50 ohm impedance of the  probe cable 
to the discrete resistor used in the probe.  

Mike

> -----Original Message-----
> From: david_instone@xxxxxxxxxxxxxx 
> [mailto:david_instone@xxxxxxxxxxxxxx]
> Sent: Friday, August 03, 2001 7:59 AM
> To: Aklein@xxxxxxxxxxxxxxxxxxxxxxxxxx
> Cc: SI
> Subject: [SI-LIST] Re: Scope probe attenuation
> 
> 
> 
> Your 1k probe may be a 1K probe when used on a 50 ohm input.  
> Check its
> actual through resistance, if it's actually 950 ohms then 
> when used on a
> 50 ohm input it will give you a 20:1 probe, ie multiply what 
> you see by
> 20.  If it's actually 1k through then multiply by 21.
> 
> 
> Adam Klein wrote:
> > 
> > Hello,
> > 
> > My question is regarding scope probe attenuation.
> > 
> > I have a Tektronix TDS640A oscilloscope which has four 
> channels designed
> > for either 50 Ohm or 1M Ohm probes I have a 1K Ohm probe 
> which works as far
> > as displaying a wave form but the amplitude is considerably 
> less than it
> > should be.  Does anybody know an equation that I can apply 
> to find out the
> > exact difference in attenuation between this probe and a 50 
> Ohm probe your
> > help is appreciated.
> > 
> > Adam
> > 
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> 
> -- 
> Regards
> 
> Dave Instone. Compliance Engineer
>  Storage Systems Development, MP24/22
>  Xyratex, Langstone Rd., Havant, Hampshire, P09 1SA, UK.
> Tel: +44 (0)23-92-496862 (direct line)
> Fax: +44 (0)23-92-496014
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