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From: Bill Sloman <bill.sloman@ieee.org>
Newsgroups: sci.electronics.design
Subject: Re: 50 ohm termination
Date: Tue, 18 Mar 2025 11:23:21 +1100
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On 18/03/2025 10:50 am, Toaster wrote:
> Thank you for the advice. In my case I have a 10Mhz signal with very
> sharp transitions (500ps, 5V) and wanted to make sure I did things
> properly.

Doing things properly may not be too difficult. Light travels at about 
one foot (30cm) per nanosecond. Longer electromagnetic waves travels at 
about two thirds of the pace in coax insulation, so 500psec is about 10cm.

You don't have have to make you terminating resistors all that compact 
to have them behave predictably with those sorts of relatively slow edges.

Faster stuff can call for symetrical arrangements of compact surface 
mount resistors and that can get messy.

Double termination - at both source and destination - will give you the 
nicest looking waveforms, and since you would only see 2.5V at the 
destination the 125mW you'd have to dissipate at the source and the 
destination shouldn't be hard to cope with.

-- 
Bill Sloman, Sydney