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Products => Test Equipment => Topic started by: AcousticBruce on April 25, 2013, 04:40:57 am

Title: 4 exact same scope probes with different characteristics!
Post by: AcousticBruce on April 25, 2013, 04:40:57 am
I bought this 4 pack of 200Mhz probes on the Ebay. I hooked all for of them to the RF out on my HP RF sweeper. 1 to 110 Mhz sweep shows some interesting behavior.

I realized that each probe had different characteristics.  1 prob at 50mhz would attenuate to a untriggerable wave form. Another at 70mhz.

Watch this vid. Its just crazy!
http://youtu.be/9v7SwegsLlc (http://youtu.be/9v7SwegsLlc)

Note: All probes a calibrated on the same machine @ 10x mode.

Questions: is this what you expect from brand new 200Mhz probes @ $58?

Lol what do you guys think of this?


Sent from my Note 2 using Tapatalk 2

Title: Re: 4 exact same scope probes with different characteristics!
Post by: amspire on April 25, 2013, 05:18:40 am
I wonder if they are "repaired" probes where someone has replaced the original scope coax cable with conventional coax cable.

Because the center wire in a scope coax is so fine, it can easily break after a lot of use or abuse.

Using conventional coax cable will result in peaks and troughs in the frequency sweep. If you view a square wave, you would also get heaps of ringing on the edges.

Is there anything printed on the cable?
Title: Re: 4 exact same scope probes with different characteristics!
Post by: rf-loop on April 25, 2013, 06:09:53 am
Perhaps this picture tell more than thousand word.

Fun.

Title: Re: 4 exact same scope probes with different characteristics!
Post by: amspire on April 25, 2013, 06:23:42 am
Perhaps this picture tell more than thousand word.

Fun.
Are the ground lead loops enough to cause a big peak at about 20MHz followed by a big dip at about 30MHz? I suspect the probe connection is not the problem, but it is worth testing.
The generator should have a 50 ohm termination, but it should perform OK without it.