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From: tgg@otter.hpl.hp.com (Tom Gardner)
Newsgroups: sci.electronics
Subject: Re: Ridiculous Impedance
Message-ID: <1770011@otter.hpl.hp.com>
Date: 24 Aug 90 07:59:54 GMT
References: <1770009@otter.hpl.hp.com>
Organization: Hewlett-Packard Laboratories, Bristol, UK.
Lines: 35

|Larry Lippman at Recognition Research Corp., Clarence, NY

| I suspect that this impedance was the result
|of other design considerations, that the value was "reasonable", and that
|no effort was made to make it conform to standard values.  

Yup.

|Such "other"
|design considerations probably include: DC resistance (because of series
|repeater power considerations); dielectric breakdown (DC repeater power
|voltage to ground is probably 3 to 5 kV); 

I _think_ they put +11kV on the centre conductor at one end and -11kV at the
other. The shield was, of course, grounded.

|shunt capacitance at working RF
|frequencies; a minimum inner conductor diameter chosen for mechanical
|strength considerations; 

Bingo. This thing has to support it's own weight as it's dropped to
the bottom of the ocean. That's part of the answer settled. Incidentally,
the core conductor was made of steel with a thin skin of copper. Total
core diameter approx 1.25cm (hey, it's a decade since I last saw the 
thing!).

|a minimum dieletric cross section chosen to
|provide mechanical flexibility; etc.
|
|If you determine that I am the first person with the correct
|answer, I will settle for a bag of Tender Vittles sent to my cats. :-)

What are they? Sounds like a drink that you attach to the back of
a steam locomotive (?!). Or some chocolate that is spread over a document 
defining how much you'll charge for doing soem work.