Copper clad steel core in coax

Terry Casey wrote:
In article , Andrew97d-
says...

I was in Wilco yesterday and noticed their coax
was 40p per metre so I snipped a couple of
inches off for a closer look.

It seems to have an aluminium foil shield and then
some more aluminium braiding, but the core is
strongly attracted to a magnet.

It looks like copper but scraping away reveals steel
of some sort.

Best avoided I suspect.

RG6.

Widely used by cable operators and despised by Bill Wright!

Probably works pretty well as, at the sort of frequencies you want to
send down coax, the current travels on the surface so a copper plated
steel wire will work very nearly as well as solid copper - I think.

--
Chris Green
·

On 11/08/2019 15:00, Terry Casey wrote:

Widely used by cable operators and despised by Bill Wright!

I have no problem with copper-coated steel inner cores per se. The
cables used by cable TV operators are generally excellent.

The steel core is copper coated but makes the cable much
stronger - a useful feature in countries like the US where
drop cables really do drop from poles! The use of steel also
makes it much cheaper.

The problem is that RG6 is a cable type whereas CT100 (and its
foam filled offspring like WF100 and PF100) is a rigid
specification.

RG6 comes in a variety of flavours varying considerably in the
amount of screening provided. Bill also claims that the bonded
aluminium screen can crack although I've never encountered it
in the good quality stuff used by cable operators.

Well I was really talking about the sort of cable the public might buy.
In those cables cracking of the screen is extremely common.

As for performance, though, it is very similar to CT100 et al,
having a loss figure that only deviates from that of CT100 by
a fraction of a dB. Both types are ~20dB per 100 metres at
862MHz.

About 18.7dB

Bill

In message , Chris Green
writes
Terry Casey wrote:
In article , Andrew97d-
says...

I was in Wilco yesterday and noticed their coax
was 40p per metre so I snipped a couple of
inches off for a closer look.

It seems to have an aluminium foil shield and then
some more aluminium braiding, but the core is
strongly attracted to a magnet.

It looks like copper but scraping away reveals steel
of some sort.

Best avoided I suspect.

RG6.

Widely used by cable operators and despised by Bill Wright!

Probably works pretty well as, at the sort of frequencies you want to
send down coax, the current travels on the surface so a copper plated
steel wire will work very nearly as well as solid copper - I think.

As already stated, the coax described is like RG6 - a pretty standard
'drop' cable for cable TV installations. And yes - at the higher
frequencies, the RF flows on the outside of the inner conductor, where
the copper is. However, I'm not sure what the implications are for use
where the coax also carries DC power (for example, when feeding a
satellite LNB). ISTR that it is not recommended (especially for long
runs) because apart from the general voltage drop, it can affect the
point where the polarization switches.
--
Ian

I used to do this. The magnet was actually on a key ring so one could attach
a bunch of keys to a metal object.
Brian

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"Norman Wells" wrote in message
...
On 11/08/2019 12:16, Andrew wrote:

I was in Wilco yesterday and noticed their coax
was 40p per metre so I snipped a couple of
inches off for a closer look.

It seems to have an aluminium foil shield and then
some more aluminium braiding, but the core is
strongly attracted to a magnet.

Do you normally carry a magnet round with you in case you come across a
bit of coax in need of testing?

Just asking.

If you have a mobile phone often the bit that holds the lid shut is a
magnet.
Brian

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"Max Demian" wrote in message
o.uk...
On 11/08/2019 12:45, Norman Wells wrote:
On 11/08/2019 12:16, Andrew wrote:

I was in Wilco yesterday and noticed their coax
was 40p per metre so I snipped a couple of
inches off for a closer look.

It seems to have an aluminium foil shield and then
some more aluminium braiding, but the core is
strongly attracted to a magnet.

Do you normally carry a magnet round with you in case you come across a
bit of coax in need of testing?

Just asking.

Well he obviously carries a wire cutter so he can nick wire.

--
Max Demian

Yes, but if one needs to solder braid its rather an issue!
It has been around for a long time though so has to be useful or nobody
would sell it.
I think the worst stuff I ever got was some white coax that at the end
seemed to be quite well screened and pretty tough. After two years outside
the pvc outside started to crack and let water in. Obviously indoor coax!

Brian

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The Sofa of Brian Gaff...

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Note this Signature is meaningless.!
"Terry Casey" wrote in message
...
In article , Andrew97d-
says...

I was in Wilco yesterday and noticed their coax
was 40p per metre so I snipped a couple of
inches off for a closer look.

It seems to have an aluminium foil shield and then
some more aluminium braiding, but the core is
strongly attracted to a magnet.

It looks like copper but scraping away reveals steel
of some sort.

Best avoided I suspect.

RG6.

Widely used by cable operators and despised by Bill Wright!

The steel core is copper coated but makes the cable much
stronger - a useful feature in countries like the US where
drop cables really do drop from poles! The use of steel also
makes it much cheaper.

The problem is that RG6 is a cable type whereas CT100 (and its
foam filled offspring like WF100 and PF100) is a rigid
specification.

RG6 comes in a variety of flavours varying considerably in the
amount of screening provided. Bill also claims that the bonded
aluminium screen can crack although I've never encountered it
in the good quality stuff used by cable operators.

When you buy it, though, you have no way of knowing what the
quality is like.

As for performance, though, it is very similar to CT100 et al,
having a loss figure that only deviates from that of CT100 by
a fraction of a dB. Both types are ~20dB per 100 metres at
862MHz.

--

Terry

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On 12/08/2019 08:09, Brian Gaff wrote:

I used to do this. The magnet was actually on a key ring so one could attach
a bunch of keys to a metal object.

Was it good at wiping your credit card data too?

In article , Andrew97d-
says...

So what is this stuff :-

https://www.toolstation.com/doncaste...e-ct100/p76103

Described as CT100 and satellite cable ?, but it does look as though
it has copper foil and braiding and 75 ohm so must be suitable for
freeview ?.

Well, it isn't CT100 for a start as it has a foam dielectric
(CT100 is semi airspaced) but now seems to have been adopted
as a generic term. I wouldn't expect it to be used by a
manufacturer, though.

The T should be an F (for foam) and the first letter is
usually that of the manufacturers name, thus PF100 is branded
Philex and WF100 is Webro.

It would be interesting to know what name appears on the outer
jacket of the cable.

So long as it conforms to the specification, it will be fine -
I note that there are no negative reviews.

--

Terry

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In article ,
says...

On 11/08/2019 15:00, Terry Casey wrote:

As for performance, though, it is very similar to CT100 et al,
having a loss figure that only deviates from that of CT100 by
a fraction of a dB. Both types are ~20dB per 100 metres at
862MHz.

About 18.7dB


Interesting. My 20dB figure was from memory but I've just
looked at my cable calculator spreadsheet which I've built up
over many years covering a wide variety of coax.

I can vary frequency and length - very useful for calculayng
the slop between 45MHz and 570MHz for the Dulwich museum
design, for example.

I've no idea which manufacturers' data I originally consultef
but the figures I have are 19.76dB for CT100 and 20.02dB for
RG6 but I note that the RG6 figure @ 750MHz is the 18.7dB you
quoted! (18.4dB for CT100).


--

Terry

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In article -
september.org, lid says...

In article ,
says...

On 11/08/2019 15:00, Terry Casey wrote:

As for performance, though, it is very similar to CT100 et al,
having a loss figure that only deviates from that of CT100 by
a fraction of a dB. Both types are ~20dB per 100 metres at
862MHz.

About 18.7dB


Interesting. My 20dB figure was from memory but I've just
looked at my cable calculator spreadsheet which I've built up
over many years covering a wide variety of coax.

I can vary frequency and length - very useful for calculayng
the slop between 45MHz and 570MHz for the Dulwich museum
design, for example.

I've no idea which manufacturers' data I originally consultef
but the figures I have are 19.76dB for CT100 and 20.02dB for
RG6 but I note that the RG6 figure @ 750MHz is the 18.7dB you
quoted! (18.4dB for CT100).

Hmmm. Just looked at Satcure's website and they give the
figure of 18.7dB for CT100 (as you said), 18.3dB for WF100 and
19.7dB for RG6.

Looks like I need to update my spreadsheet!

--

Terry

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