"Andy Cowley" wrote in message
...

Phil Allison wrote:

"Andy Cowley" wrote in message
...
doug wrote:

Mogami makes coaxial that is very good
Studios use it all the time.

For video. It's no good, it's 75 ohm, you'd need
4 ohm or 8 ohm for speakers. Anyway it seem to cost
a dollar an inch.

;-)

** It is not possible to make a 8 ohm co-ax cable.

But it *is* possible to make an interwoven cable with lots of
insulated strands have a characteristic of 8 ohms.

Such cable was sold as "Tocord" and by Mogami too IIRC.


........... Phil


Did ya notice the smileys? Irony is lost on you?


** One only smiley - no irony at all in sight.


Litzendracht wire (q.v) is what you are describing. Oh, and it is possible
to make
8 ohm coax although I can't conceive of a reason for doing so.


** Lemme see ..... hmmmm ..... what on earth has an 8 ohm impedance
???? .....

Practically nothing ...... hmmmm - just a few stupid speakers
......

Not worth bothering with really - who would spend their money on
fancy speaker cables ???

No-one of course !!!!

How silly of me ...........




Assuming an air dielectric (relative permittivity, Er ~= 1) and a 1 mm
diameter inner conductor, the inside diameter of the outer conductor
would need to be 1.14 mm. If we consider a more realistic polythene
or ETFE (cousin to PTFE) dielectric (Er ~= 2.6) then the dimension
would be 1.24 mm. - not impossible at all. In fact if you wound some
copper tape over RG213 and used the outer and your tape, with the
original jacket as the dielectric, you'd probably be pretty close.


** Reckon you can make one with a 2mm dia core ( ie 3 sq mm of copper )
0.1 mm thick insulation then 3 sq mm of outer copper and that is still a
practical and flexible cable ???

If so, you have a nice little earner on your hands - shame about the 4
nF per metre capacitance though.




.............. Phil