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General => General Chat => Topic started by: G7PSK on May 10, 2012, 12:38:15 pm

Title: Oscilloscope probes adjustments (position of)
Post by: G7PSK on May 10, 2012, 12:38:15 pm
Hi I am looking at oscilloscope probes and some of them have the trim adjustment in the probes and others at the BNC. end and some I have seen even have them at both ends. What I have no idea of is which layout is best and why. Do I go for the ones with the trims in the probe or the BNC. Or are the one with adjustment both ends better and are those harder to adjust. Which is most likely to get out of adjustment sooner etc. All thought on this are most useful.
Title: Re: Oscilloscope probes adjustments (position of)
Post by: mikeselectricstuff on May 10, 2012, 03:40:42 pm
Not really an issue - more important are things like ergonomics, how flexible the cable is, how good spring-hooks are etc.
Title: Re: Oscilloscope probes adjustments (position of)
Post by: w2aew on May 10, 2012, 06:54:35 pm
...and, make sure that you get probes that are rated for (or exceed) the bandwidth of your scope, and have a compensation range that includes the input capacitance of your scope.
Title: Re: Oscilloscope probes adjustments (position of)
Post by: saturation on May 10, 2012, 07:37:59 pm
For single adjustment probes, it doesn't matter which end [ although in theory, the BNC end gets less banged about, if you treat your probes roughly].  However, if you have adjustments on both ends: BNC and probe handle, chances are it has both high and low frequency compensation.  The 2-end adjustment probes are often more costly, and typically have higher frequency response than single adjusts.  The high-end compensation is rarely adjusted compared to the low end.  Some probes has both adjustments on the BNC end, and can have 2 - 3 adjust screws.

Its good practice to check compensation before each daily use or if you are skeptical of any result; since its basically an adjustable cap changes in ambient temperature can make it drift about.   Most of the time you'll just check the compensation, and not need to adjust it.

Hi I am looking at oscilloscope probes and some of them have the trim adjustment in the probes and others at the BNC. end and some I have seen even have them at both ends. What I have no idea of is which layout is best and why. Do I go for the ones with the trims in the probe or the BNC. Or are the one with adjustment both ends better and are those harder to adjust. Which is most likely to get out of adjustment sooner etc. All thought on this are most useful.
Title: Re: Oscilloscope probes adjustments (position of)
Post by: Rufus on May 10, 2012, 08:01:45 pm
...and, make sure that you get probes that are rated for (or exceed) the bandwidth of your scope, and have a compensation range that includes the input capacitance of your scope.

Doesn't compensation at the scope end (where you can only add to the scope capacitance) mean a larger fixed capacitance at the probe end to accommodate the worst case scope?

Asking the expert here :)