On Feb 14, 2:14*pm, Jeff Liebermann wrote:
On Sun, 14 Feb 2010 01:33:58 -0800 (PST), phaedrus

wrote:
why are transmitters normalised to 50 ohms
when clearly 450 ohms would enable us to enjoy cheaper, do-it-
yourself, lower loss feeders?

A 450 ohm coaxial cable would be rather large.
* Zo = 450 = 138 log(b/a) * (where b=OD and a=ID)
For an inner conductor diameter of 1 mm, the outer shield diameter
would need to be 1800 mm or about 71 inches.

--
Jeff Liebermann * *
150 Felker St #D * *http://www.LearnByDestroying.com
Santa Cruz CA 95060http://802.11junk.com
Skype: JeffLiebermann * * AE6KS * *831-336-2558

I understand the Navy used to have some coaxial line you could drive
through. The center conducter was hung from huge ceramic insulators
similar to those used by the power company.

Jimmie