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Probe into probes. What's up?
jonpaul:
Hello, very fine but.....
1/ Your shots Time/div much too slow to see fine structure of transient response and aberration.
Use a 1 ns or faster /div. on DL7440 Yokogawa, or TEK 7904/7104/7B10/7B15.
Unsure what the Sigeilnt scopes are capable of.
2/ There are Many poorly made or old 50 Ohm terms/feedthrough are about. Check the BW and Zo of your terms on a wideband network analyzer or impedance analyzer at least 1 Ghz.
We found the Mini Circuits and old EGG are the best, most robust and widest BW.
3/ No need for any feedthrough in scope testing if scope of plugin has a50 Ohm inut.
That is better than an external feedthrough term.
Enjoy,
Jon
tautech:
--- Quote from: jonpaul on February 06, 2023, 10:48:02 am ---Hello, very fine but.....
1/ Your shots Time/div much too slow to see fine structure of transient response and aberration.
Use a 1 ns or faster /div. on DL7440 Yokogawa, or TEK 7904/7104/7B10/7B15.
Unsure what the Sigeilnt scopes are capable of.
2/ There are Many poorly made or old 50 Ohm terms/feedthrough are about. Check the BW and Zo of your terms on a wideband network analyzer or impedance analyzer at least 1 Ghz.
We found the Mini Circuits and old EGG are the best, most robust and widest BW.
3/ No need for any feedthrough in scope testing if scope of plugin has a50 Ohm inut.
That is better than an external feedthrough term.
Enjoy,
Jon
--- End quote ---
Please see and understand first 2 screenshots in this earlier post:
https://www.eevblog.com/forum/testgear/probe-into-probes-whats-up/msg4678768/#msg4678768
We require the Bodnar pulser to be externally terminated into 50 Ohms to provide a 25 Ohm source for probe HF calibration, risetime and step response tests against a previously saved reference trace that used the scopes internal 50 Ohm input.
We are using a 2 GHz rated 4ch DSO and for you the EU link:
https://www.siglenteu.com/digital-oscilloscopes/sds6000a/
Fastest timebase is 100ps/div
jonpaul:
Tautech:
Many thanks, good link for the scope.
still do not see any shots at fast sweep, only the 10 nS/div, can you show shots like those references with fine detail at 1 nS..200 pS/div?
All my work was at 50 Ohms, no probes jut the pulser>>scope at 50 Ohms internal.
Thus a bit different than your very interesting probe tests.
Be good to do a check of feedthru 50 Ohm BNC/SMA terms, of various brands and ages: LeoB>>50 Ohm Term>>1 M scope to see the cheges in term VSWR at fast edge.
Enjoy,
Jon
Bud:
--- Quote from: jonpaul on February 06, 2023, 01:06:46 am ---1/ We used P6046 in 1971..1975 with the Sequerra Tuner at 10.7 and 100 MHz. Entire tuner RF/IF was full differential.
--- End quote ---
How important the ground lead length on P6046 is for signal integrity? Same as for a single ended probe or is it more for electrical safety of the input FETs?
jonpaul:
bud, as P6046 is differential, indeed ground lead legnth is not as,critical as in single ended probes.
However the HF CMRR rolloff limit the effectiveness thus the ground clip is,useful.
Since the FET front end has a CM and DM voltage limit, the CM input 1 r input 2 to ground voltage can be easier exceeded if no ground or a,long ground,lead with attendant high inductance is present.
We always used the standard ground lead
So not as much for safety (only low,V use of these probes) but to protect the ET inputs.
Jon
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