I've several short (a few feet) lengths of RG6 that I
would like to "strongly coerce" into assuming a particular
dressing.
Securing the cables to a stationary surface isn't practical
without significantly lengthening them and distorting
their "natural" routing.
But, ISTM that I should be able to slip each cable into
a comparable diameter copper (?) pipe and then use traditional
tools to bend that pipe into the appropriate configuration.
I'd have to observe constraints like minimum bend radius
but are there other issues that I might "discover" down the
road?
Don Y <blockedofcourse@foo.invalid> wrote:
I've several short (a few feet) lengths of RG6 that I
would like to "strongly coerce" into assuming a particular
dressing.
Securing the cables to a stationary surface isn't practical
without significantly lengthening them and distorting
their "natural" routing.
But, ISTM that I should be able to slip each cable into
a comparable diameter copper (?) pipe and then use traditional
tools to bend that pipe into the appropriate configuration.
I'd have to observe constraints like minimum bend radius
but are there other issues that I might "discover" down the
road?
You’re planning to make a random- length shotgun balun.
Cheers
Phil Hobbs
Phil Hobbs wrote:
Don Y wrote:
I've several short (a few feet) lengths of RG6 that I
would like to "strongly coerce" into assuming a particular
dressing.
Securing the cables to a stationary surface isn't practical
without significantly lengthening them and distorting
their "natural" routing.
But, ISTM that I should be able to slip each cable into
a comparable diameter copper (?) pipe and then use traditional
tools to bend that pipe into the appropriate configuration.
I'd have to observe constraints like minimum bend radius
but are there other issues that I might "discover" down the
road?
You’re planning to make a random- length shotgun balun.
Bazooka balun.
Phil Hobbs wrote:
Phil Hobbs wrote:
Don Y wrote:
I've several short (a few feet) lengths of RG6 that I
would like to "strongly coerce" into assuming a particular
dressing.
Securing the cables to a stationary surface isn't practical
without significantly lengthening them and distorting
their "natural" routing.
But, ISTM that I should be able to slip each cable into
a comparable diameter copper (?) pipe and then use traditional
tools to bend that pipe into the appropriate configuration.
I'd have to observe constraints like minimum bend radius
but are there other issues that I might "discover" down the
road?
You’re planning to make a random- length shotgun balun.
Bazooka balun.
The parasitic capacitance created between coax and its metal armor can
open a Pandora's box of potential problems.
Danke,
On Tue, 14 May 2024 19:22:12 -0000 (UTC), "Don" <g@crcomp.net> wrote:
Phil Hobbs wrote:
Phil Hobbs wrote:
Don Y wrote:
I've several short (a few feet) lengths of RG6 that I
would like to "strongly coerce" into assuming a particular
dressing.
Securing the cables to a stationary surface isn't practical
without significantly lengthening them and distorting
their "natural" routing.
But, ISTM that I should be able to slip each cable into
a comparable diameter copper (?) pipe and then use traditional
tools to bend that pipe into the appropriate configuration.
I'd have to observe constraints like minimum bend radius
but are there other issues that I might "discover" down the
road?
YouÂ’re planning to make a random- length shotgun balun.
Bazooka balun.
The parasitic capacitance created between coax and its metal armor can
open a Pandora's box of potential problems.
Danke,
Capacitance between the coax outer and the copper pipe? Proper coax
shouldn't have any external field.
John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:
On Tue, 14 May 2024 19:22:12 -0000 (UTC), "Don" <g@crcomp.net> wrote:
Phil Hobbs wrote:
Phil Hobbs wrote:
Don Y wrote:
I've several short (a few feet) lengths of RG6 that I
would like to "strongly coerce" into assuming a particular
dressing.
Securing the cables to a stationary surface isn't practical
without significantly lengthening them and distorting
their "natural" routing.
But, ISTM that I should be able to slip each cable into
a comparable diameter copper (?) pipe and then use traditional
tools to bend that pipe into the appropriate configuration.
I'd have to observe constraints like minimum bend radius
but are there other issues that I might "discover" down the
road?
YouÂ’re planning to make a random- length shotgun balun.
Bazooka balun.
The parasitic capacitance created between coax and its metal armor can
open a Pandora's box of potential problems.
Danke,
Capacitance between the coax outer and the copper pipe? Proper coax
shouldn't have any external field.
If the whole system is really coaxial, that’s true. Leaky shields, ground loops, and so on, will modify that.
Depending on the application, you may or may not care.
Cheers
Phil Hobbs
Don wrote:
Phil Hobbs wrote:
Phil Hobbs wrote:
Don Y wrote:
I've several short (a few feet) lengths of RG6 that I
would like to "strongly coerce" into assuming a particular
dressing.
Securing the cables to a stationary surface isn't practical
without significantly lengthening them and distorting
their "natural" routing.
But, ISTM that I should be able to slip each cable into
a comparable diameter copper (?) pipe and then use traditional
tools to bend that pipe into the appropriate configuration.
I'd have to observe constraints like minimum bend radius
but are there other issues that I might "discover" down the
road?
You?re planning to make a random- length shotgun balun.
Bazooka balun.
The parasitic capacitance created between coax and its metal armor can
open a Pandora's box of potential problems.
Capacitance between the coax outer and the copper pipe? Proper coax
shouldn't have any external field.
On 5/14/24 23:46, Phil Hobbs wrote:
John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:
On Tue, 14 May 2024 19:22:12 -0000 (UTC), "Don" <g@crcomp.net> wrote:
Phil Hobbs wrote:
Phil Hobbs wrote:
Don Y wrote:
I've several short (a few feet) lengths of RG6 that I
would like to "strongly coerce" into assuming a particular
dressing.
Securing the cables to a stationary surface isn't practical
without significantly lengthening them and distorting
their "natural" routing.
But, ISTM that I should be able to slip each cable into
a comparable diameter copper (?) pipe and then use traditional
tools to bend that pipe into the appropriate configuration.
I'd have to observe constraints like minimum bend radius
but are there other issues that I might "discover" down the
road?
YouÂ’re planning to make a random- length shotgun balun.
Bazooka balun.
The parasitic capacitance created between coax and its metal armor can >>>> open a Pandora's box of potential problems.
Danke,
Capacitance between the coax outer and the copper pipe? Proper coax
shouldn't have any external field.
If the whole system is really coaxial, that’s true. Leaky shields, ground >> loops, and so on, will modify that.
Depending on the application, you may or may not care.
Cheers
Phil Hobbs
I've been putting coax inside copper tubes or braids to measure
and/or reduce the transfer impedance (leakage). I did that to
measure small signals in a particle accelerator, which typically
has kicker magnets and RF cavities with kA currents and kV
voltages nearby.
A colleague developed a special low transfer impedance coax
cable for this sort of application. It had two screens with
intermediate magnetic shielding. It was unpleasant to work
with, because part of the magnetic shielding was a steel
spiral foil tape that was razor sharp. But it worked really
well.
Jeroen Belleman
Phil Hobbs wrote:
John Larkin wrote:
Don wrote:
The parasitic capacitance created between coax and its metal armor can >>>> open a Pandora's box of potential problems.
Capacitance between the coax outer and the copper pipe? Proper coax
shouldn't have any external field.
If the whole system is really coaxial, that’s true. Leaky shields, ground >> loops, and so on, will modify that.
Depending on the application, you may or may not care.
If the whole system is really coaxial, that’s true. Leaky shields, ground >> loops, and so on, will modify that.
Depending on the application, you may or may not care.
I've been putting coax inside copper tubes or braids to measure
and/or reduce the transfer impedance (leakage). I did that to
measure small signals in a particle accelerator, which typically
has kicker magnets and RF cavities with kA currents and kV
voltages nearby.
A colleague developed a special low transfer impedance coax
cable for this sort of application. It had two screens with
intermediate magnetic shielding. It was unpleasant to work
with, because part of the magnetic shielding was a steel
spiral foil tape that was razor sharp. But it worked really
well.
Jeroen Belleman wrote:
Phil Hobbs wrote:
John Larkin wrote:
Don wrote:
<snip>
The parasitic capacitance created between coax and its metal armor can >>>>> open a Pandora's box of potential problems.
Capacitance between the coax outer and the copper pipe? Proper coax
shouldn't have any external field.
If the whole system is really coaxial, that’s true. Leaky shields, ground >>> loops, and so on, will modify that.
Depending on the application, you may or may not care.
If the whole system is really coaxial, that’s true. Leaky shields, ground >>> loops, and so on, will modify that.
Depending on the application, you may or may not care.
I've been putting coax inside copper tubes or braids to measure
and/or reduce the transfer impedance (leakage). I did that to
measure small signals in a particle accelerator, which typically
has kicker magnets and RF cavities with kA currents and kV
voltages nearby.
A colleague developed a special low transfer impedance coax
cable for this sort of application. It had two screens with
intermediate magnetic shielding. It was unpleasant to work
with, because part of the magnetic shielding was a steel
spiral foil tape that was razor sharp. But it worked really
well.
Empirical observation always trumps theory for me. Did you ground [1]
the copper tubes or braids?
Note.
[1] Whitlock cynicism can be ignored:
Q. What does "ground" mean?
A. A fantasy invented by engineers to simplify their work.
_An Overview of Audio System Grounding & Interfacing_
by Bill Whitlock
Danke,
John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:
On Tue, 14 May 2024 19:22:12 -0000 (UTC), "Don" <g@crcomp.net> wrote:
Phil Hobbs wrote:
Phil Hobbs wrote:
Don Y wrote:
I've several short (a few feet) lengths of RG6 that I
would like to "strongly coerce" into assuming a particular
dressing.
Securing the cables to a stationary surface isn't practical
without significantly lengthening them and distorting
their "natural" routing.
But, ISTM that I should be able to slip each cable into
a comparable diameter copper (?) pipe and then use traditional
tools to bend that pipe into the appropriate configuration.
I'd have to observe constraints like minimum bend radius
but are there other issues that I might "discover" down the
road?
You?re planning to make a random- length shotgun balun.
Bazooka balun.
The parasitic capacitance created between coax and its metal armor can
open a Pandora's box of potential problems.
Danke,
Capacitance between the coax outer and the copper pipe? Proper coax
shouldn't have any external field.
If the whole system is really coaxial, that’s true. Leaky shields, ground >loops, and so on, will modify that.
Depending on the application, you may or may not care.
Cheers
Phil Hobbs
On Tue, 14 May 2024 21:46:35 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:
On Tue, 14 May 2024 19:22:12 -0000 (UTC), "Don" <g@crcomp.net> wrote:
Phil Hobbs wrote:
Phil Hobbs wrote:
Don Y wrote:
I've several short (a few feet) lengths of RG6 that I
would like to "strongly coerce" into assuming a particular
dressing.
Securing the cables to a stationary surface isn't practical
without significantly lengthening them and distorting
their "natural" routing.
But, ISTM that I should be able to slip each cable into
a comparable diameter copper (?) pipe and then use traditional
tools to bend that pipe into the appropriate configuration.
I'd have to observe constraints like minimum bend radius
but are there other issues that I might "discover" down the
road?
You?re planning to make a random- length shotgun balun.
Bazooka balun.
The parasitic capacitance created between coax and its metal armor can >>>> open a Pandora's box of potential problems.
Danke,
Capacitance between the coax outer and the copper pipe? Proper coax
shouldn't have any external field.
If the whole system is really coaxial, thatÂ’s true. Leaky shields, ground >> loops, and so on, will modify that.
Depending on the application, you may or may not care.
Why can't he just use tie-wraps? Or hot-melt?
I've been putting coax inside copper tubes or braids to measure
and/or reduce the transfer impedance (leakage). I did that to
measure small signals in a particle accelerator, which typically
has kicker magnets and RF cavities with kA currents and kV
voltages nearby.
A colleague developed a special low transfer impedance coax
cable for this sort of application. It had two screens with
intermediate magnetic shielding. It was unpleasant to work
with, because part of the magnetic shielding was a steel
spiral foil tape that was razor sharp. But it worked really
well.
John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:
On Tue, 14 May 2024 21:46:35 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:
On Tue, 14 May 2024 19:22:12 -0000 (UTC), "Don" <g@crcomp.net> wrote:
Phil Hobbs wrote:
Phil Hobbs wrote:
Don Y wrote:
I've several short (a few feet) lengths of RG6 that I
would like to "strongly coerce" into assuming a particular
dressing.
Securing the cables to a stationary surface isn't practical
without significantly lengthening them and distorting
their "natural" routing.
But, ISTM that I should be able to slip each cable into
a comparable diameter copper (?) pipe and then use traditional >>>>>>>> tools to bend that pipe into the appropriate configuration.
I'd have to observe constraints like minimum bend radius
but are there other issues that I might "discover" down the
road?
You?re planning to make a random- length shotgun balun.
Bazooka balun.
The parasitic capacitance created between coax and its metal armor can >>>>> open a Pandora's box of potential problems.
Danke,
Capacitance between the coax outer and the copper pipe? Proper coax
shouldn't have any external field.
If the whole system is really coaxial, that?s true. Leaky shields, ground >>> loops, and so on, will modify that.
Depending on the application, you may or may not care.
Why can't he just use tie-wraps? Or hot-melt?
What a simplistic suggestion!
Jeroen Belleman wrote:
Phil Hobbs wrote:
John Larkin wrote:
Don wrote:
<snip>
The parasitic capacitance created between coax and its metal armor can >>>>> open a Pandora's box of potential problems.
Capacitance between the coax outer and the copper pipe? Proper coax
shouldn't have any external field.
If the whole system is really coaxial, that’s true. Leaky shields, ground >>> loops, and so on, will modify that.
Depending on the application, you may or may not care.
If the whole system is really coaxial, that’s true. Leaky shields, ground >>> loops, and so on, will modify that.
Depending on the application, you may or may not care.
I've been putting coax inside copper tubes or braids to measure
and/or reduce the transfer impedance (leakage). I did that to
measure small signals in a particle accelerator, which typically
has kicker magnets and RF cavities with kA currents and kV
voltages nearby.
A colleague developed a special low transfer impedance coax
cable for this sort of application. It had two screens with
intermediate magnetic shielding. It was unpleasant to work
with, because part of the magnetic shielding was a steel
spiral foil tape that was razor sharp. But it worked really
well.
Empirical observation always trumps theory for me. Did you ground [1]
the copper tubes or braids?
Jeroen Belleman <jeroen@nospam.please> wrote:
On 5/14/24 23:46, Phil Hobbs wrote:Interesting, thanks.
John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:
On Tue, 14 May 2024 19:22:12 -0000 (UTC), "Don" <g@crcomp.net> wrote:
Phil Hobbs wrote:
Phil Hobbs wrote:
Don Y wrote:
I've several short (a few feet) lengths of RG6 that I
would like to "strongly coerce" into assuming a particular
dressing.
Securing the cables to a stationary surface isn't practical
without significantly lengthening them and distorting
their "natural" routing.
But, ISTM that I should be able to slip each cable into
a comparable diameter copper (?) pipe and then use traditional >>>>>>>> tools to bend that pipe into the appropriate configuration.
I'd have to observe constraints like minimum bend radius
but are there other issues that I might "discover" down the
road?
YouÂ’re planning to make a random- length shotgun balun.
Bazooka balun.
The parasitic capacitance created between coax and its metal armor can >>>>> open a Pandora's box of potential problems.
Danke,
Capacitance between the coax outer and the copper pipe? Proper coax
shouldn't have any external field.
If the whole system is really coaxial, that’s true. Leaky shields, ground >>> loops, and so on, will modify that.
Depending on the application, you may or may not care.
Cheers
Phil Hobbs
I've been putting coax inside copper tubes or braids to measure
and/or reduce the transfer impedance (leakage). I did that to
measure small signals in a particle accelerator, which typically
has kicker magnets and RF cavities with kA currents and kV
voltages nearby.
A colleague developed a special low transfer impedance coax
cable for this sort of application. It had two screens with
intermediate magnetic shielding. It was unpleasant to work
with, because part of the magnetic shielding was a steel
spiral foil tape that was razor sharp. But it worked really
well.
Jeroen Belleman
Is that better than real solid copper hardline or (my fave) RG402 semi-hardline?
I’d like to read more about it, if you have a reference handy.
I've several short (a few feet) lengths of RG6 that I
would like to "strongly coerce" into assuming a particular
dressing.
Securing the cables to a stationary surface isn't practical
without significantly lengthening them and distorting
their "natural" routing.
But, ISTM that I should be able to slip each cable into
a comparable diameter copper (?) pipe and then use traditional
tools to bend that pipe into the appropriate configuration.
I'd have to observe constraints like minimum bend radius
but are there other issues that I might "discover" down the
road?
On 5/15/24 01:33, Don wrote:
Jeroen Belleman wrote:
Phil Hobbs wrote:
John Larkin wrote:
Don wrote:
<snip>
The parasitic capacitance created between coax and its metal armor can >>>>>> open a Pandora's box of potential problems.
Capacitance between the coax outer and the copper pipe? Proper coax
shouldn't have any external field.
If the whole system is really coaxial, that’s true. Leaky shields, ground >>>> loops, and so on, will modify that.
Depending on the application, you may or may not care.
If the whole system is really coaxial, that’s true. Leaky shields, ground >>>> loops, and so on, will modify that.
Depending on the application, you may or may not care.
I've been putting coax inside copper tubes or braids to measure
and/or reduce the transfer impedance (leakage). I did that to
measure small signals in a particle accelerator, which typically
has kicker magnets and RF cavities with kA currents and kV
voltages nearby.
A colleague developed a special low transfer impedance coax
cable for this sort of application. It had two screens with
intermediate magnetic shielding. It was unpleasant to work
with, because part of the magnetic shielding was a steel
spiral foil tape that was razor sharp. But it worked really
well.
Empirical observation always trumps theory for me. Did you ground [1]
the copper tubes or braids?
Both ends were connected to the connector shields. The point of
the exercise was to reduce transfer impedance, which at low
frequency (<1MHz) is simply proportional to screen resistance.
Jeroen Belleman
On Wed, 15 May 2024 11:03:22 +0200, Jeroen Belleman
<jeroen@nospam.please> wrote:
On 5/15/24 01:33, Don wrote:
Jeroen Belleman wrote:
Phil Hobbs wrote:
John Larkin wrote:
Don wrote:
<snip>
The parasitic capacitance created between coax and its metal armor can >>>>>>> open a Pandora's box of potential problems.
Capacitance between the coax outer and the copper pipe? Proper coax >>>>>> shouldn't have any external field.
If the whole system is really coaxial, that’s true. Leaky shields, ground >>>>> loops, and so on, will modify that.
Depending on the application, you may or may not care.
If the whole system is really coaxial, that’s true. Leaky shields, ground >>>>> loops, and so on, will modify that.
Depending on the application, you may or may not care.
I've been putting coax inside copper tubes or braids to measure
and/or reduce the transfer impedance (leakage). I did that to
measure small signals in a particle accelerator, which typically
has kicker magnets and RF cavities with kA currents and kV
voltages nearby.
A colleague developed a special low transfer impedance coax
cable for this sort of application. It had two screens with
intermediate magnetic shielding. It was unpleasant to work
with, because part of the magnetic shielding was a steel
spiral foil tape that was razor sharp. But it worked really
well.
Empirical observation always trumps theory for me. Did you ground [1]
the copper tubes or braids?
Both ends were connected to the connector shields. The point of
the exercise was to reduce transfer impedance, which at low
frequency (<1MHz) is simply proportional to screen resistance.
Jeroen Belleman
Two parallel coaxes can make an attenuator.
What was the coupled frequency response like?
On 14/05/2024 17:51, Don Y wrote:
I've several short (a few feet) lengths of RG6 that I
would like to "strongly coerce" into assuming a particular
dressing.
Securing the cables to a stationary surface isn't practical
without significantly lengthening them and distorting
their "natural" routing.
How about semi-rigid adhesive lined heat shrink tubing?
https://www.farnell.com/datasheets/3758112.pdf
On Wed, 15 May 2024 11:03:22 +0200, Jeroen Belleman
<jeroen@nospam.please> wrote:
On 5/15/24 01:33, Don wrote:
Jeroen Belleman wrote:
Phil Hobbs wrote:
John Larkin wrote:
Don wrote:
<snip>
The parasitic capacitance created between coax and its metal armor can >>>>>>> open a Pandora's box of potential problems.
Capacitance between the coax outer and the copper pipe? Proper coax >>>>>> shouldn't have any external field.
If the whole system is really coaxial, that’s true. Leaky shields, ground
loops, and so on, will modify that.
Depending on the application, you may or may not care.
If the whole system is really coaxial, that’s true. Leaky shields, ground
loops, and so on, will modify that.
Depending on the application, you may or may not care.
I've been putting coax inside copper tubes or braids to measure
and/or reduce the transfer impedance (leakage). I did that to
measure small signals in a particle accelerator, which typically
has kicker magnets and RF cavities with kA currents and kV
voltages nearby.
A colleague developed a special low transfer impedance coax
cable for this sort of application. It had two screens with
intermediate magnetic shielding. It was unpleasant to work
with, because part of the magnetic shielding was a steel
spiral foil tape that was razor sharp. But it worked really
well.
Empirical observation always trumps theory for me. Did you ground [1]
the copper tubes or braids?
Both ends were connected to the connector shields. The point of
the exercise was to reduce transfer impedance, which at low
frequency (<1MHz) is simply proportional to screen resistance.
Jeroen Belleman
Two parallel coaxes can make an attenuator.
What was the coupled frequency response like?
On Wed, 15 May 2024 07:27:07 -0700, John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:
On Wed, 15 May 2024 11:03:22 +0200, Jeroen Belleman
<jeroen@nospam.please> wrote:
On 5/15/24 01:33, Don wrote:
Jeroen Belleman wrote:
Phil Hobbs wrote:
John Larkin wrote:
Don wrote:
<snip>
The parasitic capacitance created between coax and its metal armor can >>>>>>>> open a Pandora's box of potential problems.
Capacitance between the coax outer and the copper pipe? Proper coax >>>>>>> shouldn't have any external field.
If the whole system is really coaxial, that’s true. Leaky shields, ground
loops, and so on, will modify that.
Depending on the application, you may or may not care.
If the whole system is really coaxial, that’s true. Leaky shields, ground
loops, and so on, will modify that.
Depending on the application, you may or may not care.
I've been putting coax inside copper tubes or braids to measure
and/or reduce the transfer impedance (leakage). I did that to
measure small signals in a particle accelerator, which typically
has kicker magnets and RF cavities with kA currents and kV
voltages nearby.
A colleague developed a special low transfer impedance coax
cable for this sort of application. It had two screens with
intermediate magnetic shielding. It was unpleasant to work
with, because part of the magnetic shielding was a steel
spiral foil tape that was razor sharp. But it worked really
well.
Empirical observation always trumps theory for me. Did you ground [1]
the copper tubes or braids?
Both ends were connected to the connector shields. The point of
the exercise was to reduce transfer impedance, which at low
frequency (<1MHz) is simply proportional to screen resistance.
Jeroen Belleman
Two parallel coaxes can make an attenuator.
What was the coupled frequency response like?
Just say your data below.
On 5/15/24 16:27, John Larkin wrote:
On Wed, 15 May 2024 11:03:22 +0200, Jeroen BellemanAh sorry, this message didn't seem to get sent...
<jeroen@nospam.please> wrote:
On 5/15/24 01:33, Don wrote:
Jeroen Belleman wrote:
Phil Hobbs wrote:
John Larkin wrote:
Don wrote:
<snip>
The parasitic capacitance created between coax and its metal
armor can
open a Pandora's box of potential problems.
Capacitance between the coax outer and the copper pipe? Proper coax >>>>>>> shouldn't have any external field.
If the whole system is really coaxial, that’s true. Leaky shields, >>>>>> ground
loops, and so on, will modify that.
Depending on the application, you may or may not care.
If the whole system is really coaxial, that’s true. Leaky shields, >>>>>> ground
loops, and so on, will modify that.
Depending on the application, you may or may not care.
I've been putting coax inside copper tubes or braids to measure
and/or reduce the transfer impedance (leakage). I did that to
measure small signals in a particle accelerator, which typically
has kicker magnets and RF cavities with kA currents and kV
voltages nearby.
A colleague developed a special low transfer impedance coax
cable for this sort of application. It had two screens with
intermediate magnetic shielding. It was unpleasant to work
with, because part of the magnetic shielding was a steel
spiral foil tape that was razor sharp. But it worked really
well.
Empirical observation always trumps theory for me. Did you ground [1]
the copper tubes or braids?
Both ends were connected to the connector shields. The point of
the exercise was to reduce transfer impedance, which at low
frequency (<1MHz) is simply proportional to screen resistance.
Jeroen Belleman
Two parallel coaxes can make an attenuator.
What was the coupled frequency response like?
At low frequency, the transfer ratio was simply the ratio
of screen resistance over characteristic impedance. At medium
frequencies, a few octaves roughly around 1MHz, there was a dip,
and above that a steady rise of about 10dB/decade.
Not all cables behaved the same. RG58 is poorly screened and
doesn't have the dip. UT141 had a very deep dip.
Details at
<https://jeroen.web.cern.ch/jeroen/coaxleakage/leakage.shtml>.
Jeroen Belleman
Phil Hobbs wrote:
Jeroen Belleman wrote:
Phil Hobbs wrote:Interesting, thanks.
John Larkin wrote:I've been putting coax inside copper tubes or braids to measure
Don wrote:If the whole system is really coaxial, that’s true. Leaky shields, ground
Phil Hobbs wrote:
Phil Hobbs wrote:
Don Y wrote:
I've several short (a few feet) lengths of RG6 that I
would like to "strongly coerce" into assuming a particular
dressing.
Securing the cables to a stationary surface isn't practical
without significantly lengthening them and distorting
their "natural" routing.
But, ISTM that I should be able to slip each cable into
a comparable diameter copper (?) pipe and then use traditional >>>>>>>>> tools to bend that pipe into the appropriate configuration.
I'd have to observe constraints like minimum bend radius
but are there other issues that I might "discover" down the
road?
You?re planning to make a random- length shotgun balun.
Bazooka balun.
The parasitic capacitance created between coax and its metal armor can >>>>>> open a Pandora's box of potential problems.
Capacitance between the coax outer and the copper pipe? Proper coax
shouldn't have any external field.
loops, and so on, will modify that.
Depending on the application, you may or may not care.
and/or reduce the transfer impedance (leakage). I did that to
measure small signals in a particle accelerator, which typically
has kicker magnets and RF cavities with kA currents and kV
voltages nearby.
A colleague developed a special low transfer impedance coax
cable for this sort of application. It had two screens with
intermediate magnetic shielding. It was unpleasant to work
with, because part of the magnetic shielding was a steel
spiral foil tape that was razor sharp. But it worked really
well.
Is that better than real solid copper hardline or (my fave) RG402
semi-hardline?
I’d like to read more about it, if you have a reference handy.
I did some comparative tests. The results are here: <https://jeroen.web.cern.ch/jeroen/coaxleakage/leakage.shtml>.
There are a few references too.
On 2024-05-15 17:25, Jeroen Belleman wrote:
On 5/15/24 16:27, John Larkin wrote:
On Wed, 15 May 2024 11:03:22 +0200, Jeroen BellemanAh sorry, this message didn't seem to get sent...
<jeroen@nospam.please> wrote:
On 5/15/24 01:33, Don wrote:
Jeroen Belleman wrote:
Phil Hobbs wrote:
John Larkin wrote:
Don wrote:
<snip>
The parasitic capacitance created between coax and its metal >>>>>>>>> armor can
open a Pandora's box of potential problems.
Capacitance between the coax outer and the copper pipe? Proper coax >>>>>>>> shouldn't have any external field.
If the whole system is really coaxial, that’s true. Leaky
shields, ground
loops, and so on, will modify that.
Depending on the application, you may or may not care.
If the whole system is really coaxial, that’s true. Leaky
shields, ground
loops, and so on, will modify that.
Depending on the application, you may or may not care.
I've been putting coax inside copper tubes or braids to measure
and/or reduce the transfer impedance (leakage). I did that to
measure small signals in a particle accelerator, which typically
has kicker magnets and RF cavities with kA currents and kV
voltages nearby.
A colleague developed a special low transfer impedance coax
cable for this sort of application. It had two screens with
intermediate magnetic shielding. It was unpleasant to work
with, because part of the magnetic shielding was a steel
spiral foil tape that was razor sharp. But it worked really
well.
Empirical observation always trumps theory for me. Did you ground [1] >>>>> the copper tubes or braids?
Both ends were connected to the connector shields. The point of
the exercise was to reduce transfer impedance, which at low
frequency (<1MHz) is simply proportional to screen resistance.
Jeroen Belleman
Two parallel coaxes can make an attenuator.
What was the coupled frequency response like?
At low frequency, the transfer ratio was simply the ratio
of screen resistance over characteristic impedance. At medium
frequencies, a few octaves roughly around 1MHz, there was a dip,
and above that a steady rise of about 10dB/decade.
Not all cables behaved the same. RG58 is poorly screened and
doesn't have the dip. UT141 had a very deep dip.
Details at
<https://jeroen.web.cern.ch/jeroen/coaxleakage/leakage.shtml>.
Jeroen Belleman
Very interesting results, Jeroen. Thanks for posting them.
Is the MF resonance due to the inductive and capacitive coupling
cancelling each other? (They're 180 degrees out of phase, of course.)
The frequency is way too low to be a transmission line effect in a 1-m length.
Cheers
Phil Hobbs
On 5/14/24 23:46, Phil Hobbs wrote:
John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:
On Tue, 14 May 2024 19:22:12 -0000 (UTC), "Don" <g@crcomp.net> wrote:
Phil Hobbs wrote:
Phil Hobbs wrote:
Don Y wrote:
I've been putting coax inside copper tubes or braids to measure
and/or reduce the transfer impedance (leakage). I did that to
measure small signals in a particle accelerator, which typically
has kicker magnets and RF cavities with kA currents and kV
voltages nearby.
A colleague developed a special low transfer impedance coax
cable for this sort of application. It had two screens with
intermediate magnetic shielding. It was unpleasant to work
with, because part of the magnetic shielding was a steel
spiral foil tape that was razor sharp. But it worked really
well.
On 5/16/24 17:41, Phil Hobbs wrote:
On 2024-05-15 17:25, Jeroen Belleman wrote:
On 5/15/24 16:27, John Larkin wrote:
On Wed, 15 May 2024 11:03:22 +0200, Jeroen BellemanAh sorry, this message didn't seem to get sent...
<jeroen@nospam.please> wrote:
On 5/15/24 01:33, Don wrote:
Jeroen Belleman wrote:
Phil Hobbs wrote:
John Larkin wrote:
Don wrote:
<snip>
The parasitic capacitance created between coax and its metal >>>>>>>>>> armor can
open a Pandora's box of potential problems.
Capacitance between the coax outer and the copper pipe? Proper coax >>>>>>>>> shouldn't have any external field.
If the whole system is really coaxial, that’s true. Leaky
shields, ground
loops, and so on, will modify that.
Depending on the application, you may or may not care.
If the whole system is really coaxial, that’s true. Leaky
shields, ground
loops, and so on, will modify that.
Depending on the application, you may or may not care.
I've been putting coax inside copper tubes or braids to measure
and/or reduce the transfer impedance (leakage). I did that to
measure small signals in a particle accelerator, which typically >>>>>>> has kicker magnets and RF cavities with kA currents and kV
voltages nearby.
A colleague developed a special low transfer impedance coax
cable for this sort of application. It had two screens with
intermediate magnetic shielding. It was unpleasant to work
with, because part of the magnetic shielding was a steel
spiral foil tape that was razor sharp. But it worked really
well.
Empirical observation always trumps theory for me. Did you ground [1] >>>>>> the copper tubes or braids?
Both ends were connected to the connector shields. The point of
the exercise was to reduce transfer impedance, which at low
frequency (<1MHz) is simply proportional to screen resistance.
Jeroen Belleman
Two parallel coaxes can make an attenuator.
What was the coupled frequency response like?
At low frequency, the transfer ratio was simply the ratio
of screen resistance over characteristic impedance. At medium
frequencies, a few octaves roughly around 1MHz, there was a dip,
and above that a steady rise of about 10dB/decade.
Not all cables behaved the same. RG58 is poorly screened and
doesn't have the dip. UT141 had a very deep dip.
Details at
<https://jeroen.web.cern.ch/jeroen/coaxleakage/leakage.shtml>.
Jeroen Belleman
Very interesting results, Jeroen. Thanks for posting them.
Is the MF resonance due to the inductive and capacitive coupling
cancelling each other? (They're 180 degrees out of phase, of course.)
The frequency is way too low to be a transmission line effect in a 1-m
length.
Cheers
Phil Hobbs
The original data came from an HP3577 and I recorded only the
magnitude. Since this looks like a resonance, that's also what
I'd expect.
I can't easily go back and look again. I did this in 2009, and
I'm now retired. At the time, I was trying to make a choice for
cables connecting beam trajectory pick-ups in the CERN PSB to
their pre-amplifiers.
I suppose -but did not verify- that the dip is a resonance of
the outer inductance with a parasitic capacitance of my setup,
with the screen resistance as the damping element. I can't quite
make it fit that model though. The screen resistance doesn't
differ enough between, for example, UT141 and RG58 to explain a
deep resonance for the former, and its total absence for the
latter.
Jeroen Belleman
Jeroen Belleman <jeroen@nospam.please> wrote:
On 5/16/24 17:41, Phil Hobbs wrote:
On 2024-05-15 17:25, Jeroen Belleman wrote:
On 5/15/24 16:27, John Larkin wrote:
On Wed, 15 May 2024 11:03:22 +0200, Jeroen BellemanAh sorry, this message didn't seem to get sent...
<jeroen@nospam.please> wrote:
On 5/15/24 01:33, Don wrote:
Jeroen Belleman wrote:
Phil Hobbs wrote:
John Larkin wrote:
Don wrote:
<snip>
The parasitic capacitance created between coax and its metal >>>>>>>>>>> armor can
open a Pandora's box of potential problems.
Capacitance between the coax outer and the copper pipe? Proper coax >>>>>>>>>> shouldn't have any external field.
If the whole system is really coaxial, that’s true. Leaky
shields, ground
loops, and so on, will modify that.
Depending on the application, you may or may not care.
If the whole system is really coaxial, that’s true. Leaky
shields, ground
loops, and so on, will modify that.
Depending on the application, you may or may not care.
I've been putting coax inside copper tubes or braids to measure >>>>>>>> and/or reduce the transfer impedance (leakage). I did that to
measure small signals in a particle accelerator, which typically >>>>>>>> has kicker magnets and RF cavities with kA currents and kV
voltages nearby.
A colleague developed a special low transfer impedance coax
cable for this sort of application. It had two screens with
intermediate magnetic shielding. It was unpleasant to work
with, because part of the magnetic shielding was a steel
spiral foil tape that was razor sharp. But it worked really
well.
Empirical observation always trumps theory for me. Did you ground [1] >>>>>>> the copper tubes or braids?
Both ends were connected to the connector shields. The point of
the exercise was to reduce transfer impedance, which at low
frequency (<1MHz) is simply proportional to screen resistance.
Jeroen Belleman
Two parallel coaxes can make an attenuator.
What was the coupled frequency response like?
At low frequency, the transfer ratio was simply the ratio
of screen resistance over characteristic impedance. At medium
frequencies, a few octaves roughly around 1MHz, there was a dip,
and above that a steady rise of about 10dB/decade.
Not all cables behaved the same. RG58 is poorly screened and
doesn't have the dip. UT141 had a very deep dip.
Details at
<https://jeroen.web.cern.ch/jeroen/coaxleakage/leakage.shtml>.
Jeroen Belleman
Very interesting results, Jeroen. Thanks for posting them.
Is the MF resonance due to the inductive and capacitive coupling
cancelling each other? (They're 180 degrees out of phase, of course.)
The frequency is way too low to be a transmission line effect in a 1-m
length.
Cheers
Phil Hobbs
The original data came from an HP3577 and I recorded only the
magnitude. Since this looks like a resonance, that's also what
I'd expect.
I can't easily go back and look again. I did this in 2009, and
I'm now retired. At the time, I was trying to make a choice for
cables connecting beam trajectory pick-ups in the CERN PSB to
their pre-amplifiers.
I suppose -but did not verify- that the dip is a resonance of
the outer inductance with a parasitic capacitance of my setup,
with the screen resistance as the damping element. I can't quite
make it fit that model though. The screen resistance doesn't
differ enough between, for example, UT141 and RG58 to explain a
deep resonance for the former, and its total absence for the
latter.
Jeroen Belleman
Plus you had some pretty frou-frou RG58 there, with foil and two braids.
The normal stuff is one tinned-copper braid with about 80% coverage. You
can probably make a directional coupler with a pair of patch cords and some >heat shrink. (I should try that.)
Cheers
Phil Hobbs
On Sat, 18 May 2024 15:17:22 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
Jeroen Belleman <jeroen@nospam.please> wrote:
On 5/16/24 17:41, Phil Hobbs wrote:
On 2024-05-15 17:25, Jeroen Belleman wrote:
On 5/15/24 16:27, John Larkin wrote:
On Wed, 15 May 2024 11:03:22 +0200, Jeroen BellemanAh sorry, this message didn't seem to get sent...
<jeroen@nospam.please> wrote:
On 5/15/24 01:33, Don wrote:
Jeroen Belleman wrote:
Phil Hobbs wrote:
John Larkin wrote:
Don wrote:
<snip>
The parasitic capacitance created between coax and its metal >>>>>>>>>>>> armor can
open a Pandora's box of potential problems.
Capacitance between the coax outer and the copper pipe? Proper coax >>>>>>>>>>> shouldn't have any external field.
If the whole system is really coaxial, thatÂ’s true. Leaky >>>>>>>>>> shields, ground
loops, and so on, will modify that.
Depending on the application, you may or may not care.
If the whole system is really coaxial, thatÂ’s true. Leaky >>>>>>>>>> shields, ground
loops, and so on, will modify that.
Depending on the application, you may or may not care.
I've been putting coax inside copper tubes or braids to measure >>>>>>>>> and/or reduce the transfer impedance (leakage). I did that to >>>>>>>>> measure small signals in a particle accelerator, which typically >>>>>>>>> has kicker magnets and RF cavities with kA currents and kV
voltages nearby.
A colleague developed a special low transfer impedance coax
cable for this sort of application. It had two screens with
intermediate magnetic shielding. It was unpleasant to work
with, because part of the magnetic shielding was a steel
spiral foil tape that was razor sharp. But it worked really
well.
Empirical observation always trumps theory for me. Did you ground [1] >>>>>>>> the copper tubes or braids?
Both ends were connected to the connector shields. The point of
the exercise was to reduce transfer impedance, which at low
frequency (<1MHz) is simply proportional to screen resistance.
Jeroen Belleman
Two parallel coaxes can make an attenuator.
What was the coupled frequency response like?
At low frequency, the transfer ratio was simply the ratio
of screen resistance over characteristic impedance. At medium
frequencies, a few octaves roughly around 1MHz, there was a dip,
and above that a steady rise of about 10dB/decade.
Not all cables behaved the same. RG58 is poorly screened and
doesn't have the dip. UT141 had a very deep dip.
Details at
<https://jeroen.web.cern.ch/jeroen/coaxleakage/leakage.shtml>.
Jeroen Belleman
Very interesting results, Jeroen. Thanks for posting them.
Is the MF resonance due to the inductive and capacitive coupling
cancelling each other? (They're 180 degrees out of phase, of course.) >>>>
The frequency is way too low to be a transmission line effect in a 1-m >>>> length.
Cheers
Phil Hobbs
The original data came from an HP3577 and I recorded only the
magnitude. Since this looks like a resonance, that's also what
I'd expect.
I can't easily go back and look again. I did this in 2009, and
I'm now retired. At the time, I was trying to make a choice for
cables connecting beam trajectory pick-ups in the CERN PSB to
their pre-amplifiers.
I suppose -but did not verify- that the dip is a resonance of
the outer inductance with a parasitic capacitance of my setup,
with the screen resistance as the damping element. I can't quite
make it fit that model though. The screen resistance doesn't
differ enough between, for example, UT141 and RG58 to explain a
deep resonance for the former, and its total absence for the
latter.
Jeroen Belleman
Plus you had some pretty frou-frou RG58 there, with foil and two braids.
The normal stuff is one tinned-copper braid with about 80% coverage. You
can probably make a directional coupler with a pair of patch cords and some >> heat shrink. (I should try that.)
A practical question is what might the coupling be between two close, parallel coaxes.
Jeroen Belleman <jeroen@nospam.please> wrote:
On 5/16/24 17:41, Phil Hobbs wrote:
On 2024-05-15 17:25, Jeroen Belleman wrote:
On 5/15/24 16:27, John Larkin wrote:
On Wed, 15 May 2024 11:03:22 +0200, Jeroen BellemanAh sorry, this message didn't seem to get sent...
<jeroen@nospam.please> wrote:
On 5/15/24 01:33, Don wrote:
Jeroen Belleman wrote:
Phil Hobbs wrote:
John Larkin wrote:
Don wrote:
<snip>
The parasitic capacitance created between coax and its metal >>>>>>>>>>> armor can
open a Pandora's box of potential problems.
Capacitance between the coax outer and the copper pipe? Proper coax >>>>>>>>>> shouldn't have any external field.
If the whole system is really coaxial, that’s true. Leaky
shields, ground
loops, and so on, will modify that.
Depending on the application, you may or may not care.
If the whole system is really coaxial, that’s true. Leaky
shields, ground
loops, and so on, will modify that.
Depending on the application, you may or may not care.
I've been putting coax inside copper tubes or braids to measure >>>>>>>> and/or reduce the transfer impedance (leakage). I did that to
measure small signals in a particle accelerator, which typically >>>>>>>> has kicker magnets and RF cavities with kA currents and kV
voltages nearby.
A colleague developed a special low transfer impedance coax
cable for this sort of application. It had two screens with
intermediate magnetic shielding. It was unpleasant to work
with, because part of the magnetic shielding was a steel
spiral foil tape that was razor sharp. But it worked really
well.
Empirical observation always trumps theory for me. Did you ground [1] >>>>>>> the copper tubes or braids?
Both ends were connected to the connector shields. The point of
the exercise was to reduce transfer impedance, which at low
frequency (<1MHz) is simply proportional to screen resistance.
Jeroen Belleman
Two parallel coaxes can make an attenuator.
What was the coupled frequency response like?
At low frequency, the transfer ratio was simply the ratio
of screen resistance over characteristic impedance. At medium
frequencies, a few octaves roughly around 1MHz, there was a dip,
and above that a steady rise of about 10dB/decade.
Not all cables behaved the same. RG58 is poorly screened and
doesn't have the dip. UT141 had a very deep dip.
Details at
<https://jeroen.web.cern.ch/jeroen/coaxleakage/leakage.shtml>.
Jeroen Belleman
Very interesting results, Jeroen. Thanks for posting them.
Is the MF resonance due to the inductive and capacitive coupling
cancelling each other? (They're 180 degrees out of phase, of course.)
The frequency is way too low to be a transmission line effect in a 1-m
length.
Cheers
Phil Hobbs
The original data came from an HP3577 and I recorded only the
magnitude. Since this looks like a resonance, that's also what
I'd expect.
I can't easily go back and look again. I did this in 2009, and
I'm now retired. At the time, I was trying to make a choice for
cables connecting beam trajectory pick-ups in the CERN PSB to
their pre-amplifiers.
I suppose -but did not verify- that the dip is a resonance of
the outer inductance with a parasitic capacitance of my setup,
with the screen resistance as the damping element. I can't quite
make it fit that model though. The screen resistance doesn't
differ enough between, for example, UT141 and RG58 to explain a
deep resonance for the former, and its total absence for the
latter.
Jeroen Belleman
Plus you had some pretty frou-frou RG58 there, with foil and two braids.
The normal stuff is one tinned-copper braid with about 80% coverage. You
can probably make a directional coupler with a pair of patch cords and some heat shrink. (I should try that.)
Cheers
Phil Hobbs
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