Oscilloscope/probe question

ouverview · 22nd March 2010, 04:02 AM

hello.

Sorry if my questions a bit naïve.

I just bought a Beckman Industries Circuitmate 9020 oscilloscope for testing the DCO's on a broken snythesizer.

I think I'm looking for a 10x passive probe with high bandwidth and a BNC connection, but is there anything else I need to take into consideration?

SY · 22nd March 2010, 09:44 AM

Yes, you want to consider the probe's rated bandwidth and the expected load (especially the scope's input capacitance). Not all 10x probes are compatible with all oscilloscopes.

wakibaki · 22nd March 2010, 12:04 PM

You don't say what frequencies are involved, are we talking RF or audio synth?

A 10x probe makes the picture height 10 times smaller. Is that what you really want? I don't think the DCO outputs are likely to exceed the scope's own voltage rating.

Looking at the scope it's only 20MHz. In many instances a piece of 50 ohm coax terminated with a BNC plug at one end and 2 crocodile clips at the other is perfectly adequate. Strip about 6 inches (15cm) of the outer co-ax sheath. Make a hole in the outer braid, bend the cable double at that point, and pull the inner out through the outer to leave a pigtail to which one of the croc clips can be attached. Connect the other croc clip to the inner and fit the BNC to the other end according to the instructions. Professional labs unually have a couple of dozen of these lying around.

w

Conrad Hoffman · 23rd March 2010, 09:21 PM

A good 10X probe will give you the bandwidth your scope is capable of. A piece of coax, while very useful for many things, will limit the scopes bandwidth due to capacitance and incorrect termination. For audio work, just about anything will work, and clips on the end of a piece of coax are handy. For digital, RF or anyplace you need high bandwidth and properly square square waves, you need a 10X (not 1X) commercial probe. (or you need a 50 ohm termination, but only if you're working on a 50 ohm system, lest you load the c*** out of higher impedance systems)

Conrad

Steerpike · 23rd March 2010, 09:32 PM

I have some nice Hamegs that are switchable 1x or 10x, which is quite useful.

22nd March 2010, 04:02 AM	#1
ouverview diyAudio Member Join Date: Mar 2010	Oscilloscope/probe question hello. Sorry if my questions a bit naïve. I just bought a Beckman Industries Circuitmate 9020 oscilloscope for testing the DCO's on a broken snythesizer. I think I'm looking for a 10x passive probe with high bandwidth and a BNC connection, but is there anything else I need to take into consideration?

22nd March 2010, 09:44 AM	#2
SY diyAudio Moderator Join Date: Oct 2002 Location: Chicagoland Blog Entries: 1	Yes, you want to consider the probe's rated bandwidth and the expected load (especially the scope's input capacitance). Not all 10x probes are compatible with all oscilloscopes. __________________ If there's a sucker born every minute, where do the rest of them come from?

23rd March 2010, 09:21 PM	#4
Conrad Hoffman diyAudio Member Join Date: Mar 2007 Location: Canandaigua, NY USA	A good 10X probe will give you the bandwidth your scope is capable of. A piece of coax, while very useful for many things, will limit the scopes bandwidth due to capacitance and incorrect termination. For audio work, just about anything will work, and clips on the end of a piece of coax are handy. For digital, RF or anyplace you need high bandwidth and properly square square waves, you need a 10X (not 1X) commercial probe. (or you need a 50 ohm termination, but only if you're working on a 50 ohm system, lest you load the c*** out of higher impedance systems) Conrad __________________ I used to be an audiophool like you but then I took an arrow to the knee.

23rd March 2010, 09:32 PM	#5
Steerpike diyAudio Member Join Date: Jan 2006 Location: Johannesburg, South Africa	I have some nice Hamegs that are switchable 1x or 10x, which is quite useful. __________________ Steerpike's Toybox

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22nd March 2010, 12:04 PM	#3
wakibaki Banned Join Date: Jan 2008 Blog Entries: 2	You don't say what frequencies are involved, are we talking RF or audio synth? A 10x probe makes the picture height 10 times smaller. Is that what you really want? I don't think the DCO outputs are likely to exceed the scope's own voltage rating. Looking at the scope it's only 20MHz. In many instances a piece of 50 ohm coax terminated with a BNC plug at one end and 2 crocodile clips at the other is perfectly adequate. Strip about 6 inches (15cm) of the outer co-ax sheath. Make a hole in the outer braid, bend the cable double at that point, and pull the inner out through the outer to leave a pigtail to which one of the croc clips can be attached. Connect the other croc clip to the inner and fit the BNC to the other end according to the instructions. Professional labs unually have a couple of dozen of these lying around. w

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