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Co-as cable: truth or nonsense?



 
 
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  #21  
Old November 24th 16, 03:55 PM posted to uk.tech.digital-tv
Jim Lesurf[_2_]
external usenet poster
 
Posts: 4,183
Default Co-as cable: truth or nonsense?

In article , tony sayer

wrote:
In article , Bill Wright
scribeth thus
On 09/11/2016 20:24, R. Mark Clayton wrote:

A solid copper centre core as copper is better conductor of
electricity and signals than gold! So go for copper conductors.
Aluminium is only 61% as effective as copper.

By volume, but by weight it is better - and a quarter of the price -
so just

make thicker cores.

The ratio between the diameter of the inner and the outer sets the
characteristic impedance, so the whole cable would be thicker.

Bill


And the effect of skin effect?..


Increases the series resistance per length in a frequency dependent way.
You can then assess the effect on cable impedance and signal velocity using
the approach shown here
https://www.st-andrews.ac.uk/~www_pa...rt7/page2.html

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

  #22  
Old November 24th 16, 04:49 PM posted to uk.tech.digital-tv
R. Mark Clayton[_2_]
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Posts: 512
Default Co-as cable: truth or nonsense?

On Thursday, 24 November 2016 14:37:23 UTC, tony sayer wrote:
In article , Bill Wright
scribeth thus
On 09/11/2016 20:24, R. Mark Clayton wrote:

A solid copper centre core as copper is better conductor of electricity
and signals than gold! So go for copper conductors. Aluminium is only 61%
as effective as copper.

By volume, but by weight it is better - and a quarter of the price - so just

make thicker cores.

The ratio between the diameter of the inner and the outer sets the
characteristic impedance, so the whole cable would be thicker.

Bill


And the effect of skin effect?..
--
Tony Sayer


Only relevant at very high EMF's. The high voltage tends to concentrate conduction near the surface of the conductor, causing some overheating.
  #23  
Old November 24th 16, 04:52 PM posted to uk.tech.digital-tv
Woody[_5_]
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Posts: 1,765
Default Co-as cable: truth or nonsense?


"R. Mark Clayton" wrote in message
...
On Thursday, 24 November 2016 14:37:23 UTC, tony sayer wrote:
In article , Bill Wright
scribeth thus
On 09/11/2016 20:24, R. Mark Clayton wrote:

A solid copper centre core as copper is better conductor of
electricity
and signals than gold! So go for copper conductors. Aluminium
is only 61%
as effective as copper.

By volume, but by weight it is better - and a quarter of the
price - so just
make thicker cores.

The ratio between the diameter of the inner and the outer sets the
characteristic impedance, so the whole cable would be thicker.

Bill


And the effect of skin effect?..
--
Tony Sayer


Only relevant at very high EMF's. The high voltage tends to
concentrate conduction near the surface of the conductor, causing
some overheating.


Which is why 6.25" co-ax used on main stations like Emley has a
tubular centre conductor which has air blown through it, or at least
it did in analogue days.


--
Woody

harrogate3 at ntlworld dot com


  #24  
Old November 24th 16, 06:21 PM posted to uk.tech.digital-tv
Bill Wright[_3_]
external usenet poster
 
Posts: 1,917
Default Co-as cable: truth or nonsense?

On 24/11/2016 14:32, tony sayer wrote:
In article , Bill Wright
scribeth thus
On 09/11/2016 20:24, R. Mark Clayton wrote:

A solid copper centre core as copper is better conductor of electricity
and signals than gold! So go for copper conductors. Aluminium is only 61%
as effective as copper.

By volume, but by weight it is better - and a quarter of the price - so just

make thicker cores.

The ratio between the diameter of the inner and the outer sets the
characteristic impedance, so the whole cable would be thicker.

Bill


And the effect of skin effect?..

On?

Bill
  #25  
Old November 29th 16, 05:54 PM posted to uk.tech.digital-tv
tony sayer
external usenet poster
 
Posts: 4,978
Default Co-as cable: truth or nonsense?

In article , Woody
scribeth thus

"R. Mark Clayton" wrote in message
...
On Thursday, 24 November 2016 14:37:23 UTC, tony sayer wrote:
In article , Bill Wright
scribeth thus
On 09/11/2016 20:24, R. Mark Clayton wrote:

A solid copper centre core as copper is better conductor of
electricity
and signals than gold! So go for copper conductors. Aluminium
is only 61%
as effective as copper.

By volume, but by weight it is better - and a quarter of the
price - so just
make thicker cores.

The ratio between the diameter of the inner and the outer sets the
characteristic impedance, so the whole cable would be thicker.

Bill

And the effect of skin effect?..
--
Tony Sayer


Only relevant at very high EMF's. The high voltage tends to
concentrate conduction near the surface of the conductor, causing
some overheating.


Which is why 6.25" co-ax used on main stations like Emley has a
tubular centre conductor which has air blown through it, or at least
it did in analogue days.



Due to the way DTV is transmitted I'd reckon the flow rate might be a
tad more now. Very dry Nitrogen was used IIRC..
--
Tony Sayer



  #26  
Old November 29th 16, 06:25 PM posted to uk.tech.digital-tv
Woody[_5_]
external usenet poster
 
Posts: 1,765
Default Co-as cable: truth or nonsense?


"tony sayer" wrote in message
...
In article , Woody

scribeth thus

"R. Mark Clayton" wrote in message
...
On Thursday, 24 November 2016 14:37:23 UTC, tony sayer wrote:
In article , Bill Wright
scribeth thus
On 09/11/2016 20:24, R. Mark Clayton wrote:

A solid copper centre core as copper is better conductor of
electricity
and signals than gold! So go for copper conductors.
Aluminium
is only 61%
as effective as copper.

By volume, but by weight it is better - and a quarter of the
price - so just
make thicker cores.

The ratio between the diameter of the inner and the outer sets
the
characteristic impedance, so the whole cable would be thicker.

Bill

And the effect of skin effect?..
--
Tony Sayer

Only relevant at very high EMF's. The high voltage tends to
concentrate conduction near the surface of the conductor, causing
some overheating.


Which is why 6.25" co-ax used on main stations like Emley has a
tubular centre conductor which has air blown through it, or at least
it did in analogue days.



Due to the way DTV is transmitted I'd reckon the flow rate might be
a
tad more now. Very dry Nitrogen was used IIRC..
--




The air that I saw was dried and filtered but just plain compressed.
The same kit was also used to pressureise microwave TWTs (notice I
avoided the impolite version) on most sites. I don't recall ever
seeing any gas bottles anywhere.


--
Woody

harrogate3 at ntlworld dot com


 




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