Re: NEC-LIST: 50 versus 77 (75) ohm transmission line

From: Hal Smith <halsmith_at_email.domain.hidden>
Date: Sun, 4 Mar 2001 14:58:03 -0600

Dear Hideho,

I have some information concerning your question. The following is
from my old 1950 National Association of broadcasters Engineering
Handbook. This is from a section on design of television transmitting
systems.

P2-3-11

SURGE IMPEDANCE - The value is 51.5 ohms for all sizes. The primary
consideration in this choice was the I square R loss, with a slight
compromise on attenuation......

My degrees are in Physics. I very vaguely recall some discussion in an
Electricity and Magnetism class about the two commonly used coaxial
line impedances, 50 & 75 ohm and what situations are appropriate to
their use. However, I cannot find anything explicitly answering your
question, only the above quoted hint.

Sincerely,

Hal Smith
Received on Tue Mar 06 2001 - 23:59:28 EST

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