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Old 24th Mar 2017, 2:26 am   #32
G0HZU_JMR
Dekatron
 
Join Date: Sep 2010
Location: Cheltenham, Gloucestershire, UK.
Posts: 3,077
Default Re: Frequency counters

If this helps have a look at the specs for a typical Tektronix 200MHz x10 scope probe.

http://uk.rs-online.com/web/p/oscill...robes/4810823/

In x1 mode the claimed bandwidth is typically only 6MHz and this will be dependent on the source resistance of the circuit being tested. So in some cases where you are probing a high impedance source, the bandwidth will be even less than 6MHz in x1 mode. This is because the probe has about 100pF input capacitance in x1 mode. Take a look at the specs in the user guide below on page 4.

In case you haven't done this already, you have to compensate the probe when in x10 mode as per page 3 of the pdf below. If this isn't done properly then the probe won't have a flat frequency response up into the RF region in x10 mode. It could be that it becomes peaky or droopy at HF and VHF.
Get this wrong and the results you measure with the probe in x10 could be very inaccurate/confusing.

http://docs-europe.electrocomponents...6b80652196.pdf
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Regards, Jeremy G0HZU
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