Probes for oscilloscope interchangeable between manufacturers?

[Sam Kaan]

Are oscilloscope probes interchangeable between manufacturers?
I mean suppose a set of probe labeled as Lecroy 400Mhz probes passive
etc...
But I have an 500Mhz oscilloscope made by Tektronix. Can the probe by
Lecroy be
used in the Tektronix scope? My guess is that they are
interchangeable but I am not sure. So before picking up the phone and
ordering one, I just want to make sure.

By the way, what is the difference between passive and active probe?
what are the advantages/disadvantages?

 

[scada]

Are oscilloscope probes interchangeable between manufacturers?

Yes, as long as the input impeadance is the same.

I mean suppose a set of probe labeled as Lecroy 400Mhz probes passive
etc...
But I have an 500Mhz oscilloscope made by Tektronix. Can the probe by
Lecroy be
used in the Tektronix scope?

Yes, but limited to the 400MHZ

By the way, what is the difference between passive and active probe?
what are the advantages/disadvantages?

An Active probe requires external power. Usually plugged into a wall wart,
or battery.
An active probe may offer more sensitivity, accuracy, compare the spec
sheets.

 

[George Patrick]

An Active probe requires external power. Usually plugged into a wall wart,
or battery.
An active probe may offer more sensitivity, accuracy, compare the spec
sheets.

Many mid-range to high end scopes incorporate power connections into
the probe connectors. Newer high end scopes often will have special
connectors to support this, or there may be extra pins poking out of
the plastic shroud of the the BNC connector.

--
+--------------------------------+----------------------------------+
| George H. Patrick, III | Resources for PCB Designers on |
| [email protected] | the Web - The Designer's Den |
| [email protected] | http://www.pcb-designer.com |
+--------------------------------+----------------------------------+
| Take what you like and leave the rest... My opinion ONLY. |
+-------------------------------------------------------------------+

 

[Mac]

Are oscilloscope probes interchangeable between manufacturers?
I mean suppose a set of probe labeled as Lecroy 400Mhz probes passive
etc...
But I have an 500Mhz oscilloscope made by Tektronix. Can the probe by
Lecroy be
used in the Tektronix scope? My guess is that they are
interchangeable but I am not sure. So before picking up the phone and
ordering one, I just want to make sure.

By the way, what is the difference between passive and active probe?
what are the advantages/disadvantages?

It seems like most BNC passive probes are interchangeable, although they
may well have different bandwidths and loading characteristics.

But some faster scopes use (or can use) active probes. These probes are
not neccessarily interchangeable, since they (at least the ones I've seen)
make power as well as signal connections.

A typical active probe would be a high-impedance op-amp. The op-amp
then drives the probe cable, which is a transmission line terminated in
its characteristic impedance at the scope. This arrangement insures that
the scope sees an accurate replica of the voltage at the probe tip.

The problem with passive probes is that no matter how high the impedance
at the scope is, the probe is connected to the scope with a 50-Ohm
transmission line. At low speeds this transmission line effect doesn't
matter, but with high-speed signals, the transmission line effect can't
be ignored. A rule of thumb might be something like when the cable is less
than 5% of the wavelength (in free space) of the signal of interest, you
probably don't need an active probe. When the cable is much longer than the
wavelength, then you must use an active probe.

I should mention that there are cases where you can get by with high-speed
signals without an active probe. For example, if you want to directly look
at the output of some kind of RF amplifier or video line-driver, you can
use 50- or 75-Ohm cable of any kind all the way to the oscillliscope. At
the scope, you put a 50- or 75-Ohm resistor to ground. This allows you to
look at the signal when it is driving its design load, which is probably
what you want.

HTH

Mac
--

 

[TekMan]

Yes, as long as the input impeadance is the same.

That's not the only point to take care for. You haveto make shure the
compenstion range the probe is designed for (that is: the input
capactive loading of the scope) fits your probes needs.

Yes, but limited to the 400MHZ

Even the high frequency limit can be lower than e.g. 350 MHz or even
300MHz.

See "ABC of probes", online downladable from www.tektronix.com

An Active probe requires external power. Usually plugged into a wall wart,
or battery.
An active probe may offer more sensitivity, accuracy, compare the spec
sheets.

Active probes generally do not increase the sensivity. They decrease
the "load" (espcially the capacitve part of loading) the circuit under
test "sees" from the Scope.
So the fast pulses in a digital circuitry a less "decreased in rise
time".

Most high speed/high frequency scopes have built in power outlets for
the probes (but there is not standard, so LeCroy actives usually work
well with HP scopes, but not always wit hTektronix scopes).


HTH,
Andreas

 

[Valerio Gionco]

But I have an 500Mhz oscilloscope made by Tektronix. Can the probe by

Lecroy be
used in the Tektronix scope?

I'm no expert, but I remember that Tektronix passive 10x probes had
a small pin (connected to ground, I think) on the BNC edge. This pin magically
tells to the scope that a 10x probe is inserted and the vertical scale must
be multiplied by 10; when you use a plain BNC connector you must
take care of the 10x factor by hand.
Apart from that, passive HP probes on Tek scopes worked fine; don't know about
Lecroy or other manufacturers.

 

[Jim Meyer]

The problem with passive probes is that no matter how high the impedance
at the scope is, the probe is connected to the scope with a 50-Ohm
transmission line.

I think that if you do a little research that you will find that
although scope cables on passive probes do appear to be simply 50 Ohm
transmission lines, that they are not.

Jim

 

[mike]

I think that if you do a little research that you will find that
although scope cables on passive probes do appear to be simply 50 Ohm
transmission lines, that they are not.

Jim

They're not simple and the cable is not 50 ohm...at least on a good
passive high impedance probe.
TEK probes are EXPENSIVE...and for good reason...they work.
There's a LOT of magic, well it's really physics, that goes into
making a good probe. Any passive divider probe that has compensation
range that matches the input C of your scope will work. If you want
absolute fidelity, TEK probes are a good choice.
mike

--
Bunch of stuff For Sale and Wanted at the link below.
laptops and parts Test Equipment
Honda CB-125S
Color LCD overhead projector
Tek 2465 $800, ham radio, 30pS pulser
Tektronix Concept Books, spot welding head...
http://www.geocities.com/SiliconValley/Monitor/4710/

 

[Paul Burridge]

They're not simple and the cable is not 50 ohm...at least on a good
passive high impedance probe.
TEK probes are EXPENSIVE...and for good reason...they work.
There's a LOT of magic, well it's really physics, that goes into
making a good probe. Any passive divider probe that has compensation
range that matches the input C of your scope will work. If you want
absolute fidelity, TEK probes are a good choice.

I used a piece of speaker wire once. It was useless. Trace went
haywire. Must have been the wrong amperage.