Jeroen Belleman wrote:
Phil Hobbs wrote:
Jeroen Belleman wrote:
Phil Hobbs wrote:
John Larkin wrote:
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.
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.
Interesting, thanks.
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.
To summarize:
Apparently Jeroen uses CK50 sheathed in copper tubing while his
colleague's cable is CKB50. The transfer impedance of all tested coax
cables converge at about 54 MHz - a cable channel's common lower
frequency range.
Don Y's primary takeaway from this thread may be to solder both ends
of his conformal copper to the coax screen underneath.
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.
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