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Path: ...!Xl.tags.giganews.com!local-1.nntp.ord.giganews.com!nntp.supernews.com!news.supernews.com.POSTED!not-for-mail NNTP-Posting-Date: Wed, 15 May 2024 15:07:56 +0000 From: John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> Newsgroups: sci.electronics.design Subject: Re: Dressing RG6 Date: Wed, 15 May 2024 08:06:03 -0700 Organization: Highland Tech Reply-To: xx@yy.com Message-ID: <rpj94j19jingdjmttudjsuchcjaqd1o2du@4ax.com> References: <v204qu$99qs$1@dont-email.me> <v206dp$9pib$1@dont-email.me> <v20ads$aoqc$1@dont-email.me> <20240514b@crcomp.net> <66h74j1vfmbjvvl98jk1k017pimtinv2l5@4ax.com> <v20m3q$dgcq$1@dont-email.me> <v20n97$dq6r$1@dont-email.me> <20240514d@crcomp.net> <v21tl5$pcju$1@dont-email.me> <pfh94j988bateu0ugvf4qlttqovhc6lnn8@4ax.com> X-Newsreader: Forte Agent 3.1/32.783 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Lines: 57 X-Trace: sv3-6d7UWEI3N763NwMGb/CED+QsDL4k4LTVH1pdvtRuy2eh6S+fgaMKJNNdvXoob+NbkidJPEJyTQaRyei!r3ers4aXOfExpILflM34GQLrA7Gn4aQYs3kNM4o0MBjrEZvBvkO/aVWYgsJvYb7KsxRePt1S6bIJ!b6jRsw== X-Complaints-To: www.supernews.com/docs/abuse.html X-DMCA-Complaints-To: www.supernews.com/docs/dmca.html X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.40 Bytes: 3474 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.