Looking for cable, 2 coax with overall 3rd shield

[RobertMacy]

On Mon, 17 Mar 2014 18:26:11 -0700, amdx <nojunk@knology.net> wrote:

...snip....
The use is the Boonton RF meter the cable carries DC voltage at low
voltages, as low as 1mV.
I'm still trying to find the right cable. I'd like to find something
commercial and cut a 25ft cable into 5 pieces and put ends on them.
Mikek

What's that thin little coax called RG-179, or such? about the size of
18Awg wire, put two together [they have insulation on the outside] using
tacky glue, then add a sleeve of cheap metal brading. Often made such
'custom' cables, work fine. You're not going into Production, right? Just
for your own needs.

 

[amdx]

On 3/18/2014 9:49 AM, RobertMacy wrote:

On Mon, 17 Mar 2014 18:26:11 -0700, amdx <nojunk@knology.net> wrote:

...snip....
The use is the Boonton RF meter the cable carries DC voltage at low
voltages, as low as 1mV.
I'm still trying to find the right cable. I'd like to find something
commercial and cut a 25ft cable into 5 pieces and put ends on them.
Mikek


What's that thin little coax called RG-179, or such? about the size of
18Awg wire, put two together [they have insulation on the outside] using
tacky glue, then add a sleeve of cheap metal brading. Often made such
'custom' cables, work fine. You're not going into Production, right?
Just for your own needs.

I would like to build about 5 cables for now. I might just try some
microphone cable, then check to see if I can induce noise or generate
any piezo voltage.
Still in the market for the right cable though.
Mikek

 

[William Sommerwerck]

"amdx" wrote in message news:lg9v4v$l9o$1@dont-email.me...

I would like to build about 5 cables for now. I might just try
some microphone cable, then check to see if I can induce
noise or generate any piezo voltage.

Most cable dielectrics generate piezo voltages.

 

[amdx]

On 3/18/2014 12:26 PM, William Sommerwerck wrote:

"amdx" wrote in message news:lg9v4v$l9o$1@dont-email.me...
I would like to build about 5 cables for now. I might just try
some microphone cable, then check to see if I can induce
noise or generate any piezo voltage.

Most cable dielectrics generate piezo voltages.

Ok, see if I can generate a not unreasonable amount
of piezo electricity.
Mikek

 

[William Sommerwerck]

"amdx" wrote in message news:lga4oh$1ri$1@dont-email.me...
On 3/18/2014 12:26 PM, William Sommerwerck wrote:

Most cable dielectrics generate piezo voltages.

Ok, see if I can generate a not unreasonable amount
of piezo electricity.

All you have to do is attach the cable to a mic input, then strike the cable
against the edge of a table. Or hit it with a hammer. Almost any zetz will do.

The first time I heard this was from the cables on a moving-coil transformer.
I was really surprised. I knew of piezoelectricity, but didn't know that cable
dielectrics could generate it.

 

[amdx]

On 3/18/2014 2:25 PM, William Sommerwerck wrote:

"amdx" wrote in message news:lga4oh$1ri$1@dont-email.me...
On 3/18/2014 12:26 PM, William Sommerwerck wrote:

Most cable dielectrics generate piezo voltages.

Ok, see if I can generate a not unreasonable amount
of piezo electricity.

All you have to do is attach the cable to a mic input, then strike the
cable against the edge of a table. Or hit it with a hammer. Almost any
zetz will do.

The first time I heard this was from the cables on a moving-coil
transformer. I was really surprised. I knew of piezoelectricity, but
didn't know that cable dielectrics could generate it.

I guess the point is some cable generates less piezoelectricity than
others. I would want less.
Mikek

 

[RobertMacy]

On Tue, 18 Mar 2014 10:26:00 -0700, William Sommerwerck
<grizzledgeezer@comcast.net> wrote:

"amdx" wrote in message news:lg9v4v$l9o$1@dont-email.me...
I would like to build about 5 cables for now. I might just try
some microphone cable, then check to see if I can induce
noise or generate any piezo voltage.

Most cable dielectrics generate piezo voltages.

Don't know about piezo, but tribo-electric effect is the bane of cable
manufacturers.

 

[josephkk]

On Sat, 15 Mar 2014 19:45:56 -0700, RobertMacy <robert.a.macy@gmail.com>
wrote:

On Sat, 15 Mar 2014 16:17:01 -0700, amdx <nojunk@knology.net> wrote:

I'm looking to buy cable that has two wires, each in a shield, then this
whole thing is in another shield. Flexibility is good.
Thanks, Mikek


is that called twinax?

Belden makes it, I think

I wouldn't think so. Most twinax i have dealt with did not have shields
on the inner conductors. Check vendors for twinax structure. This would
be a specialty instrument cable.

?-)

 

[amdx]

On 3/19/2014 12:30 AM, josephkk wrote:

On Sat, 15 Mar 2014 19:45:56 -0700, RobertMacy <robert.a.macy@gmail.com
wrote:

On Sat, 15 Mar 2014 16:17:01 -0700, amdx <nojunk@knology.net> wrote:

I'm looking to buy cable that has two wires, each in a shield, then this
whole thing is in another shield. Flexibility is good.
Thanks, Mikek


is that called twinax?

Belden makes it, I think

I wouldn't think so. Most twinax i have dealt with did not have shields
on the inner conductors. Check vendors for twinax structure. This would
be a specialty instrument cable.

?-)

I called Belden, I was told, they don't make this type of cable.
Mikek

 

On Saturday, March 15, 2014 4:17:01 PM UTC-7, amdx wrote:

I'm looking to buy cable that has two wires, each in a shield, then this

whole thing is in another shield. Flexibility is good.

Thanks, Mikek

I searched for the same thing a few years back to make my own custom RCA audio connectors for my Car system when I was Competing, The best thing I could find was high grade Microphone wire, back then it was cheap but this was 10 or more years ago. They make a number of styles and types, wire gauges jacket thickness. Go to a good Music store or Electronics shop like a Reclamation center or similar store to get the best deal. You won't have the choices but you will pay much less than a Music Center.