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Need 50 ohm input on an (old) oscilloscope that has only 1M ohm inputs: BNC TEE?
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tggzzz:

--- Quote from: egonotto on October 25, 2022, 12:17:41 am ---Hello,

I tested 50 MHz rectangle once with the built-in 50 Ohm and then with a tee with two different 50 Ohm terminations and once the tee alone with the built-in 50 Ohm.

Best Regards
egonotto

--- End quote ---

What's the type of the scope, its front-end bandwidth, signal risetime and cable length?
jonpaul:
We use TEK BNC feedthru. Most of the cheap Chines knockoffs are poor quality, do not meet specs and have BNC connectors that can damage the scope BNC inputs .

Most high speed work uses a Zo probe, which can be a DIY , eg 450 Om R and thin RG 174/U 50 Ohm coax for x10.

Low Z but crazy wide band.

See Tek Ckts Concepts book on Oscilloscope probe Circuits, esp Zo probes.

https://w140.com/tekwiki/images/6/62/062-1146-00.pdf

We use P6156 TEK on 50 Ohm scopes,

https://w140.com/tekwiki/wiki/P6156

Most 1M scopes will not have the BW you seek. Bon Chance

Jon
tggzzz:

--- Quote from: jonpaul on October 25, 2022, 08:56:16 am ---We use TEK BNC feedthru. Most of the cheap Chines knockoffs are poor quality, do not meet soecs and have baynotes that can damage the scope connectors.

Most high speed work uses a Zo probe, which can be a DIY , eg 450 Om R and thin RG 174/U 50 Ohm coax for x10.

Low Z but crazy wide band.

--- End quote ---

Higher Z than simple 10Mohm *10 passive probes, at 100s of MHz.

But you obviously know that :)
chris_leyson:
Tektronix 7A42 is a 4 channel 350MHz plugin with selectable 1MOhm or 50Ohm input impedance. Also supports triggering based on the Boolean conditions of the four inputs. https://w140.com/tekwiki/wiki/7A42

Chris
egonotto:

--- Quote from: tggzzz on October 25, 2022, 08:35:25 am ---
--- Quote from: egonotto on October 25, 2022, 12:17:41 am ---...............

--- End quote ---

What's the type of the scope, its front-end bandwidth, signal risetime and cable length?

--- End quote ---

Hello,

it is a RTA4004 from Rohde & Schwarz.
1 MOhm has 0.5 GHz and 50 Ohm has 1 GHz bandwith (with risetime 350 ps).

The BNC cable length is about 1 m.

The generator rise time is about 2 ns.

Best Regards
egonotto
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