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From: john larkin <jl@glen--canyon.com>
Newsgroups: sci.electronics.design
Subject: Re: 50 ohm termination
Date: Mon, 17 Mar 2025 16:33:03 -0700
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On Mon, 17 Mar 2025 19:02:19 -0400, Toaster <toaster@dne3.net> wrote:

>Can I get away with terminating the far end of a transmission line or
>do I need a series resistor at the source and a parallel resistor at
>the destination?
>
>Thank you,
>Toaster

You can get clean wideband transmission with any impedance at the
source and a 50 ohm termination at the end. Voltages will be the same
all along the line. Assuming theoretical lossless trans lines of
course.

You can also source terminate, namely drive a 50 ohm line from a 50
ohm source. The signal at the end of the line, unterminated, will be
identical to the source internal voltage. But intermediate points will
be awful.

For extreme cases, terminate both ends at 50 ohms. That will minimize
reflections caused by imperfect connectors or terminators. It wastes a
lot of power. 


You can Spice all this.