Re: Dressing RG6

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,

--
Don, KB7RPU, https://www.qsl.net/kb7rpu
There was a young lady named Bright Whose speed was far faster than light;
She set out one day In a relative way And returned on the previous night.