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-   -   Advice on probes for a oscilloscope.... (http://www.diyaudio.com/forums/chip-amps/27893-advice-probes-oscilloscope.html)

darkmoebius 9th February 2004 10:19 PM

Advice on probes for a oscilloscope....
 
I'm in the process of buying a Tektronix 465B 100 MHz dual channel scope and need to buy probes for it. 465B specs

Someone here in the archives stated that you need to buy probes with 3x the bandwidth of your scope for accurate readings. Is this true?

I gather that a set of 1X and 10X are good for convenience, but don't know what type of current probe would be good for building tube and chip amps. Are the switchable 1X/10X probes just as good?

Tek has a P2200 Passive 1X/10X Voltage Probe that can be bought less than $10-25 on eBay.

Attenuation
1/10

Bandwidth at -3 dB
6/200 MHz

System Input Resistance
1/10 M?

Typical Input C
110/17 pF

Max Voltage
300 VRMS CAT II

Compensation Range
15 to 25 pF

Is this a good choice?

Any suggestions?

maylar 10th February 2004 12:00 AM

Those will be fine. I'm curious as to what you can buy them for... I need some too.

Cybergent 10th February 2004 12:51 AM

10/1 switchable probes usually have some disadvantages:

- Input impedance and bandwidth are lower in the 1:1 range than in the 10:1 range. Mostly 10:1 = 10MΩ 1:1 = 1MΩ. Bandwidth in 1:1 often is only half or even worse.

- The switch very often is a cause for problems.

- The overall performance is worse than in 10:1 only probes.

I prefer using a high quality 10:1 probe like TEK P6139A for acurate measurements and any cheap 10/1 probe for usual signal display.

If you work with tubes a high input impedance is very important.
Also the maximum voltage rating must be considered.

darkmoebius 10th February 2004 06:17 AM

Thanks guys...
 
Cybergent - You convinced me to simply get a Tektronix P6105A 10X probe because it is the Tek recommended part for the 465B scope.

Also, a Tek paper called "The ABC's of Probes" mentions "For applications where signal amplitudes are one-volt peak to-peak or less, a 1X probe may be more appropriate or even necessary."

I'm not likely to being much measuring in that range anytime soon.

Maylar - You can find a Tek P2200 1X/10X probe on eBay right now for $25 and no one has bid on it. If you're interested, go for it because I no longer need it.

Da5id4Vz 11th February 2004 10:38 PM

Although I prefer Tek probes, I dont know that I would buy a used one. Having shared dozens of scopes in labs and shops, I know there are an awful lot of ways that they can be abused to the point of making them painfully dysfunctional.

My current probes (the ones I use now, not the ones used for measuring current) I got for $10 a piece from Marlin P. Jones. Nope, they are not that good at all, but they are far less flaky than most of the communal probes that Ive used.

Caveat Emptor!

-Dave

yero 18th July 2012 02:24 PM

I am interested in purchasing an oscilloscope also minus probe. Can a new generic probe work for any scope or are probes specific to the model scope being purchased?

gootee 20th July 2012 05:51 AM

Often, or even usually, a generic probe will be fine. Tektronix scopes have the compensation capacitance range printed near the input connections, which the probe must comply with in order to work properly.

You would want a probe that has at least as much bandwidth as your scope, and preferably more.


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