[OT] dumb question about oscilloscope probes

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[OT] dumb question about oscilloscope probes

Victor Rosenthal 4X6GP
I like the way scope probes have a tip that hooks onto a component lead,
and a little alligator clip for the ground. So I thought I could use a
passive scope probe in the X1 position on my DVM too. I hooked one up
with a BNC-bannana adapter, but it turns out that there seems to be a
series resistance of about 250 ohms, which is inconvenient for
resistance measurements. I got the same result from several probes.

My question is, what's going on here? Schematics of probes I found all
showed that in the X1 position they were straight through.
--
73,
Victor, 4X6GP
Rehovot, Israel
Formerly K2VCO
CWops no. 5
http://www.qsl.net/k2vco/
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Re: [OT] dumb question about oscilloscope probes

Augie "Gus" Hansen

On 5/4/2020 7:47 AM, Victor Rosenthal 4X6GP wrote:
> ... My question is, what's going on here? Schematics of probes I found
> all showed that in the X1 position they were straight through.

Check the resistance of the adapter without the probe.

Gus Hansen
KB0YH


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Re: [OT] dumb question about oscilloscope probes

Alexey Kats
In reply to this post by Victor Rosenthal 4X6GP
Look at this article: "THE SECRET WORLD OF OSCILLOSCOPE PROBES" by Doug Ford.

It will explain where the extra resistance is coming from and what it
is for (TLDNR - it's for suppressing ringing of 1:10 probe at high
frequencies where the cable of the probe starts looking like a
transmission line).

http://www.dfad.com.au/links/THE%20SECRET%20WORLD%20OF%20PROBES%20OCt09.pdf

On Mon, May 4, 2020 at 6:48 AM Victor Rosenthal 4X6GP
<[hidden email]> wrote:

>
> I like the way scope probes have a tip that hooks onto a component lead,
> and a little alligator clip for the ground. So I thought I could use a
> passive scope probe in the X1 position on my DVM too. I hooked one up
> with a BNC-bannana adapter, but it turns out that there seems to be a
> series resistance of about 250 ohms, which is inconvenient for
> resistance measurements. I got the same result from several probes.
>
> My question is, what's going on here? Schematics of probes I found all
> showed that in the X1 position they were straight through.
> --
> 73,
> Victor, 4X6GP
> Rehovot, Israel
> Formerly K2VCO
> CWops no. 5
> http://www.qsl.net/k2vco/
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]



--
Alexey Kats (neko)
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Re: [OT] dumb question about oscilloscope probes

Victor Rosenthal 4X6GP
Thank you, that explains it (and more)!


73,
Victor, 4X6GP
Rehovot, Israel
Formerly K2VCO
CWops no. 5
http://www.qsl.net/k2vco/
.
On 04/05/2020 20:28, demindor . wrote:

> Look at this article: "THE SECRET WORLD OF OSCILLOSCOPE PROBES" by Doug Ford.
>
> It will explain where the extra resistance is coming from and what it
> is for (TLDNR - it's for suppressing ringing of 1:10 probe at high
> frequencies where the cable of the probe starts looking like a
> transmission line).
>
> http://www.dfad.com.au/links/THE%20SECRET%20WORLD%20OF%20PROBES%20OCt09.pdf
>
> On Mon, May 4, 2020 at 6:48 AM Victor Rosenthal 4X6GP
> <[hidden email]> wrote:
>>
>> I like the way scope probes have a tip that hooks onto a component lead,
>> and a little alligator clip for the ground. So I thought I could use a
>> passive scope probe in the X1 position on my DVM too. I hooked one up
>> with a BNC-bannana adapter, but it turns out that there seems to be a
>> series resistance of about 250 ohms, which is inconvenient for
>> resistance measurements. I got the same result from several probes.
>>
>> My question is, what's going on here? Schematics of probes I found all
>> showed that in the X1 position they were straight through.
>> --
>> 73,
>> Victor, 4X6GP
>> Rehovot, Israel
>> Formerly K2VCO
>> CWops no. 5
>> http://www.qsl.net/k2vco/
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