Thread: Probes
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Old May 31st 10, 10:33 PM posted to rec.radio.amateur.homebrew
Dave M[_3_] Dave M[_3_] is offline
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First recorded activity by RadioBanter: Mar 2010
Posts: 30
Default Probes

nobody wrote:
Gary wrote:
On May 30, 3:12?pm, Plasmah77
wrote:

The 60 MHZ specification on your
scope means its vertical amplifier and display will start to degrade
at 60 MHZ or higher in frequency.


No. It is 3dB Bandwidth. Degrade will start earlier. You will have
lost half power or in voltage around 30% of the signal.


Therefore using a probe with a 60
MHZ rating will allow you to realize all of your scope's
capabilities.


There is also a capacitance specification that should match. It is
however unlikely that it should not. Go ahead with the 100MHz probes
if you get them at a fair price.


Here are some guidelines to determine more exactly what the interaction
between the scope and probe is:
Bandwidth is BW
Risetime is Tr
BW = 0.35/Tr
Tr(overall) = Sqrt(Tr(scope)^2 + Tr(probe)^2)

Then if
Scope Tr at 60 MHz = 5.9nS
Probe Tr at 100 MHz = 3.5 nS
Overall Tr = 6.80 nS, making overall -3db bandwidth = 51.4 MHz
--
David
dgminala at mediacombb dot net