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Re: LF: Mains Cable and other transmission lines

To: [email protected]
Subject: Re: LF: Mains Cable and other transmission lines
From: "Johan Bodin" <[email protected]>
Date: Thu, 8 May 2003 19:39:46 +0200
References: <[email protected]> <[email protected]> <[email protected]> <[email protected]>
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Jim, LFers

Jim Moritz M0BMU wrote:

I have some samples of old trans-atlantic telephone coax cable - according to the labels, they are from the TAT-1, TAT-II and CANTAT-2 cables. Measuring the dimensions of these, they work out to Zo of 57, 45, and 55 ohms respectively.
I have an ITT technical journal, "Electrical Communication" from 1974 that 
contains
some detailed articles about the Cantat-2 cable, 36 pages in all. Very 
interesting
reading. One of the articles says that the cable Z was 54 ohms, so you were 
close.
The cable had 473 repeaters and it was fed with +7kV at one end and -5.4 kV
(adjustable -3.8..-7kV for compensation during magnetic storms) at the other 
end.
The current was 490 mA.


I imagine they must have been designed with low loss in mind;
Probably :-) According to the ITT publication, the total loss at the highest 
frequency
(14MHz) was over 18360 dB (yes, read it again!). In comparison, an EME path will
look like a short piece of copper wire...

73
Johan Bodin SM6LKM




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