Forums › SA Series Discussions › Suitable preamp for 10X scope probes into SA44B
- This topic has 3 replies, 2 voices, and was last updated 3 years ago by Justin Crooks.
jwoodParticipantjwood March 2, 2020 at 2:49 pm
Greetings! New potential user of the SA44B, which would fit my needs perfectly if its input could be hotrodded with an external preamp that would accept a 10X scope probe for benchtop design work. Top frequency of interest would be 150MHz and below, with signal levels on the order of 1V p-p (fundamental) that require hi-Z monitoring. Thanks for any hints or notations of use in this application!
Justin CrooksModeratorJustin Crooks March 16, 2020 at 3:14 pm
We have a probe that works from about 100 kHz to 4 GHz, with about a 500 ohm AC load to your circuit (DC blocked). We are not set up for a FET probe, which would be what you would need for a high impedance load to your circuit but a 50 ohm output impedance. This is more of an oscilloscope function.
jwoodParticipantjwood March 16, 2020 at 8:08 pm
Thanks for that, Justin; looks like I’ll have to ‘roll my own.’ We have an SA44B at work; if I’m successful with a preamp, I’ll buy one for myself!
Justin CrooksModeratorJustin Crooks March 17, 2020 at 9:34 am
If it helps there are schematics online. Typically a 1 Mohm input impedance to a non-inverting unity gain op amp, with a 50 ohm series resistor (or resistor to bring it to 50 ohms) on the output. You may want to add a ceramic [0.1 – 10] uF DC blocking cap, depending on your low frequency coverage needs.
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