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non magnetic coax

D

Daniel

Jan 1, 1970
0
Hello,

has anybody a source of non-magnetic RG174, RG178 or similar coaxial cable?



Daniel
 
R

Rich Grise

Jan 1, 1970
0
has anybody a source of non-magnetic RG174, RG178 or similar coaxial cable?
This doesn't make any sense. There is nothing magnetic about coax, unless
it's in a coil creating a magnetic field, which isn't the coax's fault.

Hope This Helps!
Rich
 
This doesn't make any sense. There is nothing magnetic about coax, unless
it's in a coil creating a magnetic field, which isn't the coax's fault.

Hope This Helps!
Rich

A tinned shield would have some nickel in it, right?
 
T

Tom Bruhns

Jan 1, 1970
0
Hello,

has anybody a source of non-magnetic RG174, RG178 or similar coaxial cable?

Daniel

Perhaps Belden types 7805 or 7805R? They apparently have a solid
copper center conductor instead of stranded copper-clad steel.

Cheers,
Tom
 
T

Tom Bruhns

Jan 1, 1970
0
This doesn't make any sense. There is nothing magnetic about coax, unless
it's in a coil creating a magnetic field, which isn't the coax's fault.

Hope This Helps!
Rich

You should try holding a magnet near normal RG-174/U sometime.
 
D

Daniel

Jan 1, 1970
0
This doesn't make any sense. There is nothing magnetic about coax

unfortunately nearly everything is magnetic. Most cables have steel
conductors that are strongly magnetic. Even if they have no steel, many
cables and connectors (everything that is gold-plated) have nickel
adhesion layers below the gold. I am doing ferromagnetic resonance
experiments, in these I can see the absorption from the cables. Our
samples are very thin films (around hundred nm), so even a very thin
metal film left from machining will cause a signal as big as the sample.
Many people have problems with ferromagnetic resonance caused probably
by the dielectric of microwave connectors, even though nobody really
knows the reason.

Daniel
 
D

Daniel

Jan 1, 1970
0
Hello Tom,

thanks for the idea.

Daniel
Perhaps Belden types 7805 or 7805R? They apparently have a solid
copper center conductor instead of stranded copper-clad steel.

Cheers,
Tom
 
B

Bill Sloman

Jan 1, 1970
0
Perhaps Belden types 7805 or 7805R? They apparently have a solid
copper center conductor instead of stranded copper-clad steel.

I just checked out an example of semi-rigid coax, and the one I looked at
used copper for the outer conductor and silver-plated copper (SPC) for the
inner.

http://www.micro-coax.com/pages/pro...axial/Semi-RigidDetails.asp?ID=UT-085C-TP-M17

Unfortunately, when I checked out RG402 and RG405 - the semi-rigid coax that
you can buy from most broadline distributors - all the manufacturer's data
sheets that I could find used silver-plated copper-clad steel wire for the
inner conductor (also known as silver-plated copper weld SPCW). Many of
Micro-coax's semi-rigid cables use the same centre conductor, but they do
seem to use silver-plated copper centre wires in at least some of their
cables - I didn't dig deep enough to find out why.

Semi-rigid cable is nice stuff, but expensive, and if you can't get it from
a distributor you quite often have to buy quite a lot more than you need.

If you called up a local manufacturer of semi-rigid cable and told them what
you needed and why you needed it you might be able to get a big enough free
sample out if them to enable you to check out the approach.
 
Hello,

has anybody a source of non-magnetic RG174, RG178 or similar coaxial cable?

Daniel

Yup I needed this to run RF to our optical pumping apparatus. Belden
9221 010. Newark part number 05F1809. The core is all copper, The
impedance is 75 ohms.

George Herold
 
D

Daniel

Jan 1, 1970
0
thank you all for your help, I've ordered both 9221 and 7805, I'll post
the results soon.


Daniel
 
R

Rich Grise

Jan 1, 1970
0
This doesn't make any sense. There is nothing magnetic about coax, unless
it's in a coil creating a magnetic field, which isn't the coax's fault.

Well, it didn't take long for my ignorance to get corrected. ;-)

If you learn something new every day, does that mean I can go back to bed
now? ;-)

Thanks!
Rich
 
T

Tom Bruhns

Jan 1, 1970
0
Well, it didn't take long for my ignorance to get corrected. ;-)

If you learn something new every day, does that mean I can go back to bed
now? ;-)

Thanks!
Rich

:) I have a friend that often says, "Any day you learn something new
is a good day." I have lots of good days, and I'm thankful for them.
Well, OK, especially the ones where the learning isn't too painful or
costly.

Cheers,
Tom
 
R

Rich Grise

Jan 1, 1970
0
:) I have a friend that often says, "Any day you learn something new
is a good day." I have lots of good days, and I'm thankful for them.
Well, OK, especially the ones where the learning isn't too painful or
costly.

Well, I must admit I wasn't very confident, having seen copperclad steel
cores. But it never occurred to me that that was what the OP was probably
referring to.

Thanks for the correction. :)

Cheers!
Rich
 
Well, it didn't take long for my ignorance to get corrected. ;-)

If you learn something new every day, does that mean I can go back to bed
now? ;-)

Thanks!
Rich

In french we say "je vais me coucher moins niaiseux a soir", which
roughly translates to "I'm going to bed less dumb tonight".
 
D

Daniel

Jan 1, 1970
0
Hello All,

both the Belden 8705 and the 9221 (75 Ohm) cable are nonmagnetic and
work well.

Thanks again for all your ideas

Daniel
 
T

Tom Bruhns

Jan 1, 1970
0
Well, I must admit I wasn't very confident, having seen copperclad steel
cores. But it never occurred to me that that was what the OP was probably
referring to.

Thanks for the correction. :)

Cheers!
Rich

Slightly off-topic: another friend pointed out an interesting
property of RG-174/U -- the type with the center conductor of copper-
clad steel strands. Most coax shows attenuation (in dB/unit length)
proportional to the square root of operating frequency, at least where
the frequency is high enough that skin depth is smaller than the
thickness of the conductors and low enough that dielectric loss isn't
significant. But because the copper on the center conductor of the
RG-174 is so thin, about a mil, and because skin depth in the magnetic
steel core is extremely small, the copper loss--and therefore the
attenuation--is nearly constant over a range of frequencies up to
roughly 10MHz. This can occasionally be an advantage.

Cheers,
Tom
 
Daniel said:
Hello All,

both the Belden 8705 and the 9221 (75 Ohm) cable are nonmagnetic and
work well.

Thanks again for all your ideas

Daniel

Oh, is the 8705 50 ohm? That would be nice.

George Herold
 
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