[Chris Siz]

I am in the UK and have a 10m length of some cheap TV aerial coax. It
came from a discount store as a TV coax extension cable. I measure the
cable diameter as 4.8mm.

(1) Is it ok to use this sort of coax for a microphone? I don't want
an impaired audio signal. The length I need to use is 3 to 4 metres.

(2) Is it ok for UHF TV or is it actually quite low grade coax and
prone to interference or mess up the aerial signal?


--



[x-posted to 3 relevant groups]

[Don Pearce]

On Sat, 03 May 2008 10:58:27 +0100, Chris Siz
wrote:

I am in the UK and have a 10m length of some cheap TV aerial coax. It
came from a discount store as a TV coax extension cable. I measure the
cable diameter as 4.8mm.

(1) Is it ok to use this sort of coax for a microphone? I don't want
an impaired audio signal. The length I need to use is 3 to 4 metres.

(2) Is it ok for UHF TV or is it actually quite low grade coax and
prone to interference or mess up the aerial signal?

If you can get hold of some better cable do so. You have two problems
here - first coax isn't balanced, which is sort of bad news for tiny
signals such as you get from a mic. And secondly, to compound that, if
you strip back a little of the outer sheath, you will find that the
screen is 90% holes - in other words, the cable is just about
unscreened.

As for using it for UHF TV, go ahead - that is what it is meant for,
and 10 meters is just about the maximum run length before you need to
think about using something better.

d

--
Pearce Consulting
http://www.pearce.uk.com

[Chris Siz]

On Sat 03 May 2008 11:10:02, Don Pearce wrote:

On Sat, 03 May 2008 10:58:27 +0100, Chris Siz
wrote:

I am in the UK and have a 10m length of some cheap TV aerial coax.
It came from a discount store as a TV coax extension cable. I
measure the cable diameter as 4.8mm.

(1) Is it ok to use this sort of coax for a microphone? I don't
want an impaired audio signal. The length I need to use is 3 to 4
metres.

(2) Is it ok for UHF TV or is it actually quite low grade coax and
prone to interference or mess up the aerial signal?

If you can get hold of some better cable do so. You have two
problems here - first coax isn't balanced, which is sort of bad
news for tiny signals such as you get from a mic. And secondly, to
compound that, if you strip back a little of the outer sheath, you
will find that the screen is 90% holes - in other words, the cable
is just about unscreened.


Um, yes. It is exactly like that. I had thought maybe they were using
very thin wires and that way getting a reasonable amount of physcial
screening but the wires I found were so sparse that it must be more
like what you describe!

As for using it for UHF TV, go ahead - that is what it is meant
for, and 10 meters is just about the maximum run length before you
need to think about using something better.

d

[Ian Jackson]

In message , Chris Siz
writes
I am in the UK and have a 10m length of some cheap TV aerial coax. It
came from a discount store as a TV coax extension cable. I measure the
cable diameter as 4.8mm.

(1) Is it ok to use this sort of coax for a microphone? I don't want
an impaired audio signal. The length I need to use is 3 to 4 metres.

(2) Is it ok for UHF TV or is it actually quite low grade coax and
prone to interference or mess up the aerial signal?


While you might get away with using your cable, good screening/shielding
becomes increasing important at the lower frequencies, as the
interfering signals (on the outside of the coax) penetrate more easily
through the outer shield. Well-screened audio would be better. In many
cases, 'flimsy' screening may be adequate at UHF (and the cable may have
low loss) but, again, well-screened cable will be better for preventing
interference. Maybe it's a case of try it and see what happens?
--
Ian

[Theo]

"Ian Jackson" wrote in message
...
In message , Chris Siz
writes
I am in the UK and have a 10m length of some cheap TV aerial coax. It
came from a discount store as a TV coax extension cable. I measure the
cable diameter as 4.8mm.

(1) Is it ok to use this sort of coax for a microphone? I don't want
an impaired audio signal. The length I need to use is 3 to 4 metres.

(2) Is it ok for UHF TV or is it actually quite low grade coax and
prone to interference or mess up the aerial signal?


While you might get away with using your cable, good screening/shielding
becomes increasing important at the lower frequencies, as the
interfering signals (on the outside of the coax) penetrate more easily
through the outer shield. Well-screened audio would be better. In many
cases, 'flimsy' screening may be adequate at UHF (and the cable may have
low loss) but, again, well-screened cable will be better for preventing
interference. Maybe it's a case of try it and see what happens?

I would have thought the converse to be true, surely the "holes" in the
screening
braid would be less of a problem at audio frequencies than at UHF?
I am thinking in terms of wavelength.

[PhattyMo[_2_]]

Theo wrote:
"Ian Jackson" wrote in message
...
In message , Chris Siz
writes
I am in the UK and have a 10m length of some cheap TV aerial coax. It
came from a discount store as a TV coax extension cable. I measure the
cable diameter as 4.8mm.

(1) Is it ok to use this sort of coax for a microphone? I don't want
an impaired audio signal. The length I need to use is 3 to 4 metres.

(2) Is it ok for UHF TV or is it actually quite low grade coax and
prone to interference or mess up the aerial signal?


While you might get away with using your cable, good screening/shielding
becomes increasing important at the lower frequencies, as the
interfering signals (on the outside of the coax) penetrate more easily
through the outer shield. Well-screened audio would be better. In many
cases, 'flimsy' screening may be adequate at UHF (and the cable may have
low loss) but, again, well-screened cable will be better for preventing
interference. Maybe it's a case of try it and see what happens?

I would have thought the converse to be true, surely the "holes" in the
screening
braid would be less of a problem at audio frequencies than at UHF?
I am thinking in terms of wavelength.



Same here. *shrug* ?

[Bob Eld]

"Chris Siz" wrote in message
...
I am in the UK and have a 10m length of some cheap TV aerial coax. It
came from a discount store as a TV coax extension cable. I measure the
cable diameter as 4.8mm.

(1) Is it ok to use this sort of coax for a microphone? I don't want
an impaired audio signal. The length I need to use is 3 to 4 metres.

(2) Is it ok for UHF TV or is it actually quite low grade coax and
prone to interference or mess up the aerial signal?


Yes, it's OK to use coax for a mic cable assuming the mic is a single ended
connection (one wire) with ground. The biggest issue is the cable
capacitance. Depending on the mic's impedance, this capacitance will
attenuate high frequencies. A low impedance mike will work better than a
high impedance mic. The accumulated capacitance in four meters of cable will
be a couple of hundred pico-farads, probably not a problem.

For UHF TV cables are usually 72 ohms. If your cable is 72 ohms, it's
probably OK. If it is 50 ohms it will still work but may degrade the picture
quality because of reflections within the cable. Try and see. If the antenna
is 300 ohms, the cable is not suitable unless matched with a balun or other
impedance matching device.

[Ian Jackson]

In message , Bob Eld
writes

"Chris Siz" wrote in message
...
I am in the UK and have a 10m length of some cheap TV aerial coax. It
came from a discount store as a TV coax extension cable. I measure the
cable diameter as 4.8mm.

(1) Is it ok to use this sort of coax for a microphone? I don't want
an impaired audio signal. The length I need to use is 3 to 4 metres.

(2) Is it ok for UHF TV or is it actually quite low grade coax and
prone to interference or mess up the aerial signal?


Yes, it's OK to use coax for a mic cable assuming the mic is a single ended
connection (one wire) with ground. The biggest issue is the cable
capacitance. Depending on the mic's impedance, this capacitance will
attenuate high frequencies. A low impedance mike will work better than a
high impedance mic. The accumulated capacitance in four meters of cable will
be a couple of hundred pico-farads, probably not a problem.

Out of interest, how does the capacitance of ordinary TV coax (which
will be 75 ohms, of course) compare with 'proper' mic cable? Of course,
a lot of audio is balanced (usually nominally 600 ohms), which makes
things generally less prone to the pick-up of interference. Unbalanced
connections via coax (even if proper screened audio cable) is
less-tolerant.

For UHF TV cables are usually 72 ohms. If your cable is 72 ohms, it's
probably OK. If it is 50 ohms it will still work but may degrade the picture
quality because of reflections within the cable.
Try and see.

As it's TV coax, it's unlikely to be 50 ohms.

If the antenna
is 300 ohms, the cable is not suitable unless matched with a balun or other
impedance matching device.

UK aerials are not 300 ohms (except for those indoor FM radio aerials
made from 300 twin feeder). I believe that, these days, they are also a
bit of rarity in the USA.
--
Ian

[Martin Griffith]

On Sat, 3 May 2008 17:01:19 +0100, in sci.electronics.design Ian
Jackson wrote:


Out of interest, how does the capacitance of ordinary TV coax (which
will be 75 ohms, of course) compare with 'proper' mic cable? Of course,
a lot of audio is balanced (usually nominally 600 ohms), which makes
things generally less prone to the pick-up of interference. Unbalanced
connections via coax (even if proper screened audio cable) is
less-tolerant.

600 ohms is dead and buried, for the audio world.The only time it is
mentioned is in data sheets, "will drive XXdB into 600R" etc


martin

[Les.]

"Martin Griffith" wrote in message
...
On Sat, 3 May 2008 17:01:19 +0100, in sci.electronics.design Ian
Jackson wrote:

600 ohms is dead and buried, for the audio world.The only time it is
mentioned is in data sheets, "will drive XXdB into 600R" etc


martin

Quite so. The concept of matching a microphone's impedance to get the best
power transfer has not been practiced for a considerable time.
Modern dynamic mics expect to look at a "bridging" impedance e.g. around 10K
for a mic having a Z of 150-200 Ohms and to operate as a voltage, rather
than a power source.
The characteristic imedance of the feeder (over a few feet) may thus be
disregarded.


Les.

[Ian Thompson-Bell]

Les. wrote:
"Martin Griffith" wrote in message
...
On Sat, 3 May 2008 17:01:19 +0100, in sci.electronics.design Ian
Jackson wrote:
600 ohms is dead and buried, for the audio world.The only time it is
mentioned is in data sheets, "will drive XXdB into 600R" etc


martin

Quite so. The concept of matching a microphone's impedance to get the best
power transfer has not been practiced for a considerable time.
Modern dynamic mics expect to look at a "bridging" impedance e.g. around 10K
for a mic having a Z of 150-200 Ohms and to operate as a voltage, rather
than a power source.

No they expect to see 1K2 to 2K not 10K and that is what most pro mic
pres provide. 10K input impedance is for bridging line levels.

Cheers

Ian

[[email protected]]

On May 3, 4:58 am, Chris Siz wrote:
I am in the UK and have a 10m length of some cheap TV aerial coax. It
came from a discount store as a TV coax extension cable. I measure the
cable diameter as 4.8mm.

(1) Is it ok to use this sort of coax for a microphone? I don't want
an impaired audio signal. The length I need to use is 3 to 4 metres.

(2) Is it ok for UHF TV or is it actually quite low grade coax and
prone to interference or mess up the aerial signal?

--

[x-posted to 3 relevant groups]

Isn't coax kind of rigid? Will the microphone need to move around?

[Chris Siz]

On Sat 03 May 2008 15:54:24, wrote:

On May 3, 4:58 am, Chris Siz wrote:
I am in the UK and have a 10m length of some cheap TV aerial
coax. It came from a discount store as a TV coax extension
cable. I measure the cable diameter as 4.8mm.

(1) Is it ok to use this sort of coax for a microphone? I don't
want an impaired audio signal. The length I need to use is 3 to
4 metres.

(2) Is it ok for UHF TV or is it actually quite low grade coax
and prone to interference or mess up the aerial signal?

--

[x-posted to 3 relevant groups]

Isn't coax kind of rigid? Will the microphone need to move around?

This cheapo coax is quite flexible. It may an indication of poor
physical resistance to squashing and also of limited copper content.

[Kevin McMurtrie]

In article ,
Chris Siz wrote:

I am in the UK and have a 10m length of some cheap TV aerial coax. It
came from a discount store as a TV coax extension cable. I measure the
cable diameter as 4.8mm.

(1) Is it ok to use this sort of coax for a microphone? I don't want
an impaired audio signal. The length I need to use is 3 to 4 metres.

(2) Is it ok for UHF TV or is it actually quite low grade coax and
prone to interference or mess up the aerial signal?

There are a few differences. TV coax will work in some conditions but
not generally.

TV coax is very brittle. The inner wire is copper-plated steel and the
outer shield is aluminum wire and aluminum foil. It will quickly crack
where it meets the connectors.

TV coax may not pass small audio signals well because of its aluminum
shield. Aluminum is extremely reactive so it is always coated with a
thin oxide layer. Higher voltages can spark through it and TV RF can
capacitively couple through it. Microphone signals might become
distorted. Cable for lower frequencies uses copper shielding.

Good microphone and instrument cable has an insulation that drains away
static electrical charges. RF coax can contain electrical charges in
the insulation that causes it to act like condenser microphone.

--
Block Google's spam and enjoy Usenet again.
Reply with Google and I won't hear from you.

[SteveE]

Kevin McMurtrie wrote:
In article ,
Chris Siz wrote:

I am in the UK and have a 10m length of some cheap TV aerial coax. It
came from a discount store as a TV coax extension cable. I measure the
cable diameter as 4.8mm.

(1) Is it ok to use this sort of coax for a microphone? I don't want
an impaired audio signal. The length I need to use is 3 to 4 metres.

(2) Is it ok for UHF TV or is it actually quite low grade coax and
prone to interference or mess up the aerial signal?

There are a few differences. TV coax will work in some conditions but
not generally.

TV coax is very brittle. The inner wire is copper-plated steel and the
outer shield is aluminum wire and aluminum foil. It will quickly crack
where it meets the connectors.
Not necessarily in fact a lot of TV coax is entirely copper.

TV coax may not pass small audio signals well because of its aluminum
shield. Aluminum is extremely reactive so it is always coated with a
thin oxide layer.

Yes, the laws of nature decided that.
Higher voltages can spark through it and TV RF can
capacitively couple through it. Microphone signals might become
distorted. Cable for lower frequencies uses copper shielding.

Rubbish.

Good microphone and instrument cable has an insulation that drains away
static electrical charges. RF coax can contain electrical charges in
the insulation that causes it to act like condenser microphone.

Rubbish again. Where do you get this knowledge from?

Steve

--
Say no to ISPs selling your private browsing history to advertisers who
will then send you targeted adverts, as well as, potentially,
compromising your security on line.
Please visit: http://www.badphorm.co.uk/page.php?2 for more information
and please sign the rapidly growing on line petition at
http://petitions.pm.gov.uk/ispphorm/ if you don't want to see this
happening.

Thanks

[jim stewart]

Say no to ISPs selling your private browsing history to advertisers who
will then send you targeted adverts, as well as, potentially, compromising
your security on line.

so that is why I get so much porno spam .......

[SteveE]

jim stewart wrote:
Say no to ISPs selling your private browsing history to advertisers who
will then send you targeted adverts, as well as, potentially, compromising
your security on line.

so that is why I get so much porno spam .......


Well only you can answer that Jim ;-)

But you are off the hook with Phorm as they promise not to profile that
sort of stuff.

That promise seems a bit hollow as Phorm, previously known as 121 media
were involved in malware (people on page) before this. I wouldn't trust
them one bit.

Steve

--
Say no to ISPs selling your private browsing history to advertisers who
will then send you targeted adverts, as well as, potentially,
compromising your security on line.
Please visit: http://www.badphorm.co.uk/page.php?2 for more information
and please sign the rapidly growing on line petition at
http://petitions.pm.gov.uk/ispphorm/ if you don't want to see this
happening.

[Richard Crowley]

"SteveE" wrote ...
Kevin McMurtrie wrote:
Higher voltages can spark through it and TV RF can
capacitively couple through it. Microphone signals might become
distorted. Cable for lower frequencies uses copper shielding.

Rubbish.

Indeed. Take it out with the rest of the trash.

Good microphone and instrument cable has an insulation that drains away
static electrical charges. RF coax can contain electrical charges in the
insulation that causes it to act like condenser microphone.

Rubbish again. Where do you get this knowledge from?

Looks like a reference to some hi-Z cable that is made with condctive
fabric (or other such substance) to reduce the cable microphonic
tendencies due to the triboelectric effect of some kinds of dielectric
insulation.

[Chris Siz]

On Sat 03 May 2008 19:05:41, Kevin McMurtrie wrote:

In article ,
Chris Siz wrote:

I am in the UK and have a 10m length of some cheap TV aerial
coax. It came from a discount store as a TV coax extension
cable. I measure the cable diameter as 4.8mm.

(1) Is it ok to use this sort of coax for a microphone? I don't
want an impaired audio signal. The length I need to use is 3 to
4 metres.

(2) Is it ok for UHF TV or is it actually quite low grade coax
and prone to interference or mess up the aerial signal?

There are a few differences. TV coax will work in some conditions
but not generally.

TV coax is very brittle. The inner wire is copper-plated steel
and the outer shield is aluminum wire and aluminum foil. It will
quickly crack where it meets the connectors.

TV coax may not pass small audio signals well because of its
aluminum shield. Aluminum is extremely reactive so it is always
coated with a thin oxide layer. Higher voltages can spark through
it and TV RF can capacitively couple through it. Microphone
signals might become distorted. Cable for lower frequencies uses
copper shielding.

Good microphone and instrument cable has an insulation that drains
away static electrical charges. RF coax can contain electrical
charges in the insulation that causes it to act like condenser
microphone.


I am the OP and as you can probably tell I am no electronics or
radio expert. However even my limited knowledge struggles to
believe some of the points you have made.

Forgive me if it's more obvious to others but your's is not some
sort of funny posting is it?

[Phil Allison]

"Chris Siz"

I am the OP and as you can probably tell I am no electronics or
radio expert. However even my limited knowledge struggles to
believe some of the points you have made.


** Always seems hard to believe the facts when you know very little about
some matter.

Cos the truth is never as simple as you would like to be.


Forgive me if it's more obvious to others but your's is not some
sort of funny posting is it?


** Certainly yours is very funny.

Looks every inch like some **** head's pathetic troll.




...... Phil

[Kevin McMurtrie]

In article ,
Chris Siz wrote:

On Sat 03 May 2008 19:05:41, Kevin McMurtrie wrote:

In article ,
Chris Siz wrote:

I am in the UK and have a 10m length of some cheap TV aerial
coax. It came from a discount store as a TV coax extension
cable. I measure the cable diameter as 4.8mm.

(1) Is it ok to use this sort of coax for a microphone? I don't
want an impaired audio signal. The length I need to use is 3 to
4 metres.

(2) Is it ok for UHF TV or is it actually quite low grade coax
and prone to interference or mess up the aerial signal?

There are a few differences. TV coax will work in some conditions
but not generally.

TV coax is very brittle. The inner wire is copper-plated steel
and the outer shield is aluminum wire and aluminum foil. It will
quickly crack where it meets the connectors.

TV coax may not pass small audio signals well because of its
aluminum shield. Aluminum is extremely reactive so it is always
coated with a thin oxide layer. Higher voltages can spark through
it and TV RF can capacitively couple through it. Microphone
signals might become distorted. Cable for lower frequencies uses
copper shielding.

Good microphone and instrument cable has an insulation that drains
away static electrical charges. RF coax can contain electrical
charges in the insulation that causes it to act like condenser
microphone.


I am the OP and as you can probably tell I am no electronics or
radio expert. However even my limited knowledge struggles to
believe some of the points you have made.

Forgive me if it's more obvious to others but your's is not some
sort of funny posting is it?

It's not a funny posting. TV signals are high frequency RF and they
behave very differently from audio. The requirements for good TV
performance are very different from microphone cable.

TV needs:
- Very constant RF impedance to reduce signal reflections and smearing.
- Low absorption of very high frequencies in the insulation.
- High conductance along the surface of the center wire.
- Low inductance and capacitance.
- Stretch resistant enough to hang from antennas and rooftops.

Music cable:
- No oxide layers.
- Low capacitance.
- Insulation that does not produce electric noise on impact.
- Resistant to being stepped on and bent.
- Very high shielding coverage to avoid noise pickup from nearby power
cables.

You can buy general purpose coax that works perfectly for both audio and
RF. It's a bit pricey. Since you mentioned it being cheap TV coax, I
doubt it's a good performer outside of TV frequencies.

The real answer is to TRY IT.

--
Block Google's spam and enjoy Usenet again.
Reply with Google and I won't hear from you.

[JosephKK[_2_]]

On Sun, 04 May 2008 12:41:01 +0100, Chris Siz
wrote:

On Sat 03 May 2008 19:05:41, Kevin McMurtrie wrote:

In article ,
Chris Siz wrote:

I am in the UK and have a 10m length of some cheap TV aerial
coax. It came from a discount store as a TV coax extension
cable. I measure the cable diameter as 4.8mm.

(1) Is it ok to use this sort of coax for a microphone? I don't
want an impaired audio signal. The length I need to use is 3 to
4 metres.

(2) Is it ok for UHF TV or is it actually quite low grade coax
and prone to interference or mess up the aerial signal?

There are a few differences. TV coax will work in some conditions
but not generally.

TV coax is very brittle. The inner wire is copper-plated steel
and the outer shield is aluminum wire and aluminum foil. It will
quickly crack where it meets the connectors.

TV coax may not pass small audio signals well because of its
aluminum shield. Aluminum is extremely reactive so it is always
coated with a thin oxide layer. Higher voltages can spark through
it and TV RF can capacitively couple through it. Microphone
signals might become distorted. Cable for lower frequencies uses
copper shielding.

Good microphone and instrument cable has an insulation that drains
away static electrical charges. RF coax can contain electrical
charges in the insulation that causes it to act like condenser
microphone.


I am the OP and as you can probably tell I am no electronics or
radio expert. However even my limited knowledge struggles to
believe some of the points you have made.

Forgive me if it's more obvious to others but your's is not some
sort of funny posting is it?

He thinks he is earnest. Most of these effects do occur in some
applications. If you have read the whole thread you will have seen
even more other use case issues. Not all of which apply to your use.
Kevin's biggest problem is that he does not know what the boundaries
of applicability are of the various things he thinks he understands.

In general, it will work OK for low fidelity / casual use. It will
not work well, and it may be a reliability problem. Forget about it
for good amateur or serious use.

[Grimly Curmudgeon]

Kevin McMurtrie wrote:

There are a few differences. TV coax will work in some conditions but
not generally.

TV coax is very brittle. The inner wire is copper-plated steel and the
outer shield is aluminum wire and aluminum foil. It will quickly crack
where it meets the connectors.

TV coax may not pass small audio signals well because of its aluminum
shield. Aluminum is extremely reactive so it is always coated with a
thin oxide layer. Higher voltages can spark through it and TV RF can
capacitively couple through it. Microphone signals might become
distorted. Cable for lower frequencies uses copper shielding.

Good microphone and instrument cable has an insulation that drains away
static electrical charges. RF coax can contain electrical charges in
the insulation that causes it to act like condenser microphone.

stands back in amazement

You know, I don't think I've seen such a collection tripe in a single
post for at least a week. Well done.

To the OP: Give it a go - it's free, and if it works, fine, you won't
harm anything.
--
Dave
GS850x2 XS650 SE6a

"It's a moron working with power tools.
How much more suspenseful can you get?"
- House

[Ian Jackson]

In message , Grimly Curmudgeon
writes
Kevin McMurtrie wrote:

There are a few differences. TV coax will work in some conditions but
not generally.

TV coax is very brittle. The inner wire is copper-plated steel and the
outer shield is aluminum wire and aluminum foil. It will quickly crack
where it meets the connectors.

TV coax may not pass small audio signals well because of its aluminum
shield. Aluminum is extremely reactive so it is always coated with a
thin oxide layer. Higher voltages can spark through it and TV RF can
capacitively couple through it. Microphone signals might become
distorted. Cable for lower frequencies uses copper shielding.

Good microphone and instrument cable has an insulation that drains away
static electrical charges. RF coax can contain electrical charges in
the insulation that causes it to act like condenser microphone.

stands back in amazement

You know, I don't think I've seen such a collection tripe in a single
post for at least a week. Well done.

To the OP: Give it a go - it's free, and if it works, fine, you won't
harm anything.

There is one point which definitely has validity. Without checking, I
recall that electrostatic charges can build up in the dielectric, and
this causes a 'rustling' sound when the coax is bent. I believe that
some coax - where this problem has been minimised - is specced
specifically as being 'non-microphonic'. A Google is called for.
--
Ian

[Don Pearce]

On Sat, 10 May 2008 13:28:16 +0100, Ian Jackson
wrote:

In message , Grimly Curmudgeon
writes
Kevin McMurtrie wrote:

There are a few differences. TV coax will work in some conditions but
not generally.

TV coax is very brittle. The inner wire is copper-plated steel and the
outer shield is aluminum wire and aluminum foil. It will quickly crack
where it meets the connectors.

TV coax may not pass small audio signals well because of its aluminum
shield. Aluminum is extremely reactive so it is always coated with a
thin oxide layer. Higher voltages can spark through it and TV RF can
capacitively couple through it. Microphone signals might become
distorted. Cable for lower frequencies uses copper shielding.

Good microphone and instrument cable has an insulation that drains away
static electrical charges. RF coax can contain electrical charges in
the insulation that causes it to act like condenser microphone.

stands back in amazement

You know, I don't think I've seen such a collection tripe in a single
post for at least a week. Well done.

To the OP: Give it a go - it's free, and if it works, fine, you won't
harm anything.

There is one point which definitely has validity. Without checking, I
recall that electrostatic charges can build up in the dielectric, and
this causes a 'rustling' sound when the coax is bent. I believe that
some coax - where this problem has been minimised - is specced
specifically as being 'non-microphonic'. A Google is called for.

Yup, the search term you need is the triboelectric effect. It is a
surface phenomenon that can affect dielectric materials. The usual
cure in non-microphonic cables is a layer of moderate conductivity -
usually thin and black - just inside the outer screen.

d
--
Pearce Consulting
http://www.pearce.uk.com

[JosephKK[_2_]]

On Sat, 10 May 2008 13:23:41 GMT, (Don Pearce)
wrote:

On Sat, 10 May 2008 13:28:16 +0100, Ian Jackson
wrote:

In message , Grimly Curmudgeon
writes
Kevin McMurtrie wrote:

There are a few differences. TV coax will work in some conditions but
not generally.

TV coax is very brittle. The inner wire is copper-plated steel and the
outer shield is aluminum wire and aluminum foil. It will quickly crack
where it meets the connectors.

TV coax may not pass small audio signals well because of its aluminum
shield. Aluminum is extremely reactive so it is always coated with a
thin oxide layer. Higher voltages can spark through it and TV RF can
capacitively couple through it. Microphone signals might become
distorted. Cable for lower frequencies uses copper shielding.

Good microphone and instrument cable has an insulation that drains away
static electrical charges. RF coax can contain electrical charges in
the insulation that causes it to act like condenser microphone.

stands back in amazement

You know, I don't think I've seen such a collection tripe in a single
post for at least a week. Well done.

To the OP: Give it a go - it's free, and if it works, fine, you won't
harm anything.

There is one point which definitely has validity. Without checking, I
recall that electrostatic charges can build up in the dielectric, and
this causes a 'rustling' sound when the coax is bent. I believe that
some coax - where this problem has been minimised - is specced
specifically as being 'non-microphonic'. A Google is called for.

Yup, the search term you need is the triboelectric effect. It is a
surface phenomenon that can affect dielectric materials. The usual
cure in non-microphonic cables is a layer of moderate conductivity -
usually thin and black - just inside the outer screen.

d

Yep. In extreme cases they use silver powder as well. It gets
Expen$ive. Takes really expensive connectors. Mebbe over $100 a pop by
now. Not to mention several $k for the tool kit and training to use
them.

[Don Pearce]

On Sat, 03 May 2008 19:39:45 +0100, Walt Davidson
wrote:

On Sat, 03 May 2008 11:05:41 -0700, Kevin McMurtrie
wrote:

TV coax is very brittle. The inner wire is copper-plated steel and the
outer shield is aluminum wire and aluminum foil. It will quickly crack
where it meets the connectors.

What planet do you live on? I have never seen TV coax as you
describe. Coax with copper-plated steel inner conductor is mostly
used as data cable (ethernet).

73 de G3NYY

The stuff with foil is higher quality, used mostly for satellite dish
feeder. TV coax is just a copper inner with about half a dozen fine
strands for a screen.

d

--
Pearce Consulting
http://www.pearce.uk.com

[Dead Paul]

On Sat, 03 May 2008 18:41:27 +0000, Don Pearce wrote:

On Sat, 03 May 2008 19:39:45 +0100, Walt Davidson
wrote:

On Sat, 03 May 2008 11:05:41 -0700, Kevin McMurtrie
wrote:

TV coax is very brittle. The inner wire is copper-plated steel and the
outer shield is aluminum wire and aluminum foil. It will quickly crack
where it meets the connectors.

What planet do you live on? I have never seen TV coax as you describe.
Coax with copper-plated steel inner conductor is mostly used as data
cable (ethernet).

73 de G3NYY

The stuff with foil is higher quality, used mostly for satellite dish
feeder. TV coax is just a copper inner with about half a dozen fine
strands for a screen.

Yes, and i've seen rg58 like that at maplin electronics!

Just for your information :-)


d

--
___ _______ ___ ___ ___ __ ____
/ _ \/ __/ _ | / _ \ / _ \/ _ |/ / / / /
/ // / _// __ |/ // / / ___/ __ / /_/ / /__
/____/___/_/ |_/____/ /_/ /_/ |_\____/____/

[Dave Platt]

TV coax is very brittle. The inner wire is copper-plated steel and the
outer shield is aluminum wire and aluminum foil. It will quickly crack
where it meets the connectors.

What planet do you live on? I have never seen TV coax as you
describe. Coax with copper-plated steel inner conductor is mostly
used as data cable (ethernet).

75-ohm with copper-coated steel center conductor is often used for
outdoor cable-company coax runs. The steel core gives it enough
tensile strength to allow long runs to hang between poles (and between
pole and house) without stretching. This stuff is often a "hardline"
coax, with an aluminum outer shield... very low RF leakage, which is
an important issue for cable companies.

Indoor TV coax is sometimes RG-59, sometimes RG-6. It usually seems
to have a solid-copper center conductor (to allow for termination via
a crimp-on F connector). The shield may be anything from one layer of
braid with poor coverage, up to a quad shield (two layers of braid,
two layers of foil). It may be fairly stiff.

Coax which is optimized for microphone usage tends to be relatively
flexible (stranded center conductor, compliant jacket), and I
understand that the better varieties are designed to minimize the
generation of triboelectric noise (which occurs when the cable is
moved, as a result of static or piezoelectric effects).

Using TV coax for a microphone ought not to be harmful, but it's
probably not the best choice, and I'd do it only if a limited budget
made it impossible to get something better suited to the purpose.

Useful reference: http://www.belden.com/pdfs/Techpprs/tpbroad.htm

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

[Dead Paul]

On Sat, 03 May 2008 19:39:45 +0100, Walt Davidson wrote:

On Sat, 03 May 2008 11:05:41 -0700, Kevin McMurtrie
wrote:

TV coax is very brittle. The inner wire is copper-plated steel and the
outer shield is aluminum wire and aluminum foil. It will quickly crack
where it meets the connectors.

What planet do you live on? I have never seen TV coax as you describe.
Coax with copper-plated steel inner conductor is mostly used as data cable
(ethernet).

You want to see the crap which passes for rg58 at maplin electronics.




73 de G3NYY

--
___ _______ ___ ___ ___ __ ____
/ _ \/ __/ _ | / _ \ / _ \/ _ |/ / / / /
/ // / _// __ |/ // / / ___/ __ / /_/ / /__
/____/___/_/ |_/____/ /_/ /_/ |_\____/____/

[Chris Siz]

On Sat 03 May 2008 22:24:49, Dead Paul wrote:

On Sat, 03 May 2008 19:39:45 +0100, Walt Davidson wrote:

On Sat, 03 May 2008 11:05:41 -0700, Kevin McMurtrie
wrote:

TV coax is very brittle. The inner wire is copper-plated steel
and the outer shield is aluminum wire and aluminum foil. It will
quickly crack where it meets the connectors.

What planet do you live on? I have never seen TV coax as you
describe. Coax with copper-plated steel inner conductor is mostly
used as data cable (ethernet).

You want to see the crap which passes for rg58 at maplin
electronics.



Maplins selling crap merchandise doesn't surprise me. (Though to be
fair, it does sell the odd good item too.)

But where would I go to get half-decent cables in relatively short
lengths (not 50m drums) without paying a fortune for ultra quality
dedicated-hobbyist stuff or exhorbitant delivery charges?

[Kevin McMurtrie]

In article ,
Chris Siz wrote:

On Sat 03 May 2008 22:24:49, Dead Paul wrote:

On Sat, 03 May 2008 19:39:45 +0100, Walt Davidson wrote:

On Sat, 03 May 2008 11:05:41 -0700, Kevin McMurtrie
wrote:

TV coax is very brittle. The inner wire is copper-plated steel
and the outer shield is aluminum wire and aluminum foil. It will
quickly crack where it meets the connectors.

What planet do you live on? I have never seen TV coax as you
describe. Coax with copper-plated steel inner conductor is mostly
used as data cable (ethernet).

You want to see the crap which passes for rg58 at maplin
electronics.



Maplins selling crap merchandise doesn't surprise me. (Though to be
fair, it does sell the odd good item too.)

But where would I go to get half-decent cables in relatively short
lengths (not 50m drums) without paying a fortune for ultra quality
dedicated-hobbyist stuff or exhorbitant delivery charges?

(Trimming response to rec.audio.tech)

I know what you mean. The local stores in Silicon Valley categorize
cable according to glamor rather than performance. I can't go into a
Guitar Center without becoming very angry.

I've purchased good bulk music wire and connectors from he
http://www.best-tronics.com/guitar-cable/index.aspx
Click on "Bulk Cable & Conn" for plain cable by the foot.

It might be US only, though.

--
Block Google's spam and enjoy Usenet again.
Reply with Google and I won't hear from you.

[Michael A. Terrell]

Walt Davidson wrote:

On Sat, 03 May 2008 11:05:41 -0700, Kevin McMurtrie
wrote:

TV coax is very brittle. The inner wire is copper-plated steel and the
outer shield is aluminum wire and aluminum foil. It will quickly crack
where it meets the connectors.

What planet do you live on? I have never seen TV coax as you
describe. Coax with copper-plated steel inner conductor is mostly
used as data cable (ethernet).


Then you've never seen the wire used by cable TV and Satellite TV
companies. Pure copper is too expensive these days, and too soft for
repeated flexing. If you want to pay over a dollar a foot for copper
core TV coax, go ahead. The last time I had to buy some it was about
eight times the price of the foil shield W/braid TV coax, and useless
for UHF. Use a magnet, and see for yourself. The copper plating smears
when cut with dykes, and makes the coated steel appear to be solid
copper.


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http://improve-usenet.org/index.html


Use any search engine other than Google till they stop polluting USENET
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[Jeff Liebermann]

On Sat, 03 May 2008 21:23:08 -0400, "Michael A. Terrell"
wrote:

Then you've never seen the wire used by cable TV and Satellite TV
companies. Pure copper is too expensive these days, and too soft for
repeated flexing. If you want to pay over a dollar a foot for copper
core TV coax, go ahead. The last time I had to buy some it was about
eight times the price of the foil shield W/braid TV coax, and useless
for UHF. Use a magnet, and see for yourself. The copper plating smears
when cut with dykes, and makes the coated steel appear to be solid
copper.

Well, I did just that. I grabbed a magnet off the fridge and went
through my pile of RG-6/u CATV coax jumpers and cables. The really
old stuff had an all copper center conductor. The fairly current
stuff has a copperweld or CCS (copper clad steel) center conductor. I
would guess that about 90% of what's in the pile (about 100 cables) is
CCS. Amazing:
http://www.fushiinternational.com/Products.aspx?p=Bimetallic
http://www.fushiinternational.com/Pr...spx?p=CCSCable

However, much of the RG-6/u cable is "satellite grade", which means it
should work to about 2GHz with minimal loss. I've been using the quad
shielded variety (apparently with a CCS center conductor) for years
for Wi-Fi at 2.4GHz with about 10dB/100ft attenuation (measured). The
loss is in the dielectric, not in the center conductor cladding. I
would say that it works just fine at UHF (300-3000MHz).

Incidentally, I blundered across this data sheet for RG-6/u. They can
make it just about any way you want it, and still call it RG-6/u. Note
the line with:
6) Braiding coverage: Between 30 - 97% available;
I can't imagine who would want to buy 30% coverage outer shielding.
http://www.tootoo.com/supplier/product-detail/6251149/RG6%252fU.html

As for the coax being brittle, that's possible if it were plenum rated
cable for running through air ducts. The stuff is suppose to be "low
smoke" when burning. It tends to be rather stiff and brittle. For
RG-6/u, the flexibility is largely in the type of braid and outer
jacket. Quad shielded is going to be rather stiff. Judging by the
mixture in my junk box, I have cables that range from super flexible
(for the back of HDTV installs) to super stiff (gel filled for direct
burial). Your mileage and stiffness may vary.

As for the suitability as a microphone cable, I dunno. The original
posting had no useful descriptions of the microphone, the found cable,
or the equipment to which it will be connected. 4.8mm O.D. could be a
wide variety of possible coax cables. I'm lazy and don't wanna guess.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

[Michael A. Terrell]

Jeff Liebermann wrote:

However, much of the RG-6/u cable is "satellite grade", which means it
should work to about 2GHz with minimal loss. I've been using the quad
shielded variety (apparently with a CCS center conductor) for years
for Wi-Fi at 2.4GHz with about 10dB/100ft attenuation (measured). The
loss is in the dielectric, not in the center conductor cladding. I
would say that it works just fine at UHF (300-3000MHz).


I was talking about higher losses in a copper braided shield, VS foil
& steel braid. I used to test & specify all the passivies for a major
MSO CATV company.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

[Chris S]

On Sun 04 May 2008 04:28:55, Jeff Liebermann wrote:

Incidentally, I blundered across this data sheet for RG-6/u. They
can make it just about any way you want it, and still call it
RG-6/u. Note the line with:
6) Braiding coverage: Between 30 - 97% available;
I can't imagine who would want to buy 30% coverage outer
shielding.
http://www.tootoo.com/supplier/produ...9/RG6%252fU.ht
ml



I too have started to feeling that there is a heck of lot more
variation than I realised in how coax cables can be made and yet are
still conform to some particular technical specification.

I came across some interesting articles at "abc cables". Here are some
which caught my eye. http://www.abccables.com/technical-support.html

Wire? or Cable?
RG6 Copper vs. Copper Clad Steel
RG59 vs. RG6
Better Copper?

I would like to get other (supplier's) info as that site is quite
useful. Has anyone got any links to these sort of explanatory
articles?

[Michael A. Terrell]

Chris S wrote:

On Sun 04 May 2008 04:28:55, Jeff Liebermann wrote:

Incidentally, I blundered across this data sheet for RG-6/u. They
can make it just about any way you want it, and still call it
RG-6/u. Note the line with:
6) Braiding coverage: Between 30 - 97% available;
I can't imagine who would want to buy 30% coverage outer
shielding.
http://www.tootoo.com/supplier/produ...9/RG6%252fU.ht
ml


I too have started to feeling that there is a heck of lot more
variation than I realised in how coax cables can be made and yet are
still conform to some particular technical specification.

I came across some interesting articles at "abc cables". Here are some
which caught my eye. http://www.abccables.com/technical-support.html

Wire? or Cable?
RG6 Copper vs. Copper Clad Steel
RG59 vs. RG6
Better Copper?

I would like to get other (supplier's) info as that site is quite
useful. Has anyone got any links to these sort of explanatory
articles?


You can slap RG- numbers on anything. It stopped being a military
standard a long time ago. Belden, Alpha, Times wire websites should
have some good white papers. RG meant 'Radio Guide', and all early coax
was braided copper shielding. Their is still some RF coax made this way,
but it uses teflon and silver plated copper and is VERY expensive.

http://www.belden.com/pdfs/Cable101/Shielding.pdf page 32 states 'Braid
is for low frequency, foil for high frequency'.

http://www.belden.com/pdfs/03Belden_Master_Catalog/06Coaxial_Cables/06Coaxial_Cables.pdf
is the coaxial cable part of the Belden catalog. about 4 MB download.

http://www.belden.com/pdfs/03Belden_Master_Catalog/2006_Belden_Catalog.pdf
is their full catalog, about 38 MB download.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

[Jeff Liebermann]

On Sat, 03 May 2008 21:23:08 -0400, "Michael A. Terrell"
wrote:

Use a magnet, and see for yourself. The copper plating smears
when cut with dykes, and makes the coated steel appear to be solid
copper.

Trivia:
Dike = Diagonal Cutters
http://en.wikipedia.org/wiki/Diagonal_pliers
Dyke = Lesbian
http://en.wikipedia.org/wiki/Dyke_(lesbian)
Dyke or Dike = Earthen wall or dam
http://en.wikipedia.org/wiki/Dike_%28construction%29

Methinks "dikes" would be the correct spelling.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

[Ian Jackson]

In message , Jeff Liebermann
writes
On Sat, 03 May 2008 21:23:08 -0400, "Michael A. Terrell"
wrote:

Use a magnet, and see for yourself. The copper plating smears
when cut with dykes, and makes the coated steel appear to be solid
copper.

Trivia:
Dike = Diagonal Cutters
http://en.wikipedia.org/wiki/Diagonal_pliers
Dyke = Lesbian
http://en.wikipedia.org/wiki/Dyke_(lesbian)
Dyke or Dike = Earthen wall or dam
http://en.wikipedia.org/wiki/Dike_%28construction%29

Methinks "dikes" would be the correct spelling.


In the NE of England, 'dyke' also = 'ditch'.
From Wiktionary:
Dike or dyke (construction), either a long wall or bank built to keep
out the sea or enclose or separate land, or the ditch from which the
material was dug, or the combination of the two.

Apologies for the digression....
--
Ian

[Michael A. Terrell]

Jeff Liebermann wrote:

On Sat, 03 May 2008 21:23:08 -0400, "Michael A. Terrell"
wrote:

Use a magnet, and see for yourself. The copper plating smears
when cut with dykes, and makes the coated steel appear to be solid
copper.

Trivia:
Dike = Diagonal Cutters
http://en.wikipedia.org/wiki/Diagonal_pliers
Dyke = Lesbian
http://en.wikipedia.org/wiki/Dyke_(lesbian)
Dyke or Dike = Earthen wall or dam
http://en.wikipedia.org/wiki/Dike_%28construction%29

Methinks "dikes" would be the correct spelling.


I have seen it written as dykes more often, but who knows? Are you
saying lesbians can't cut wire? ;-)?


--
http://improve-usenet.org/index.html


Use any search engine other than Google till they stop polluting USENET
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