On 2/23/18 1:33 PM, Bob kb8tq wrote: > Hi > >> On Feb 23, 2018, at 4:23 PM, Attila Kinali <attila@kinali.ch> wrote: >> >> Hoi Bob, >> >> On Thu, 22 Feb 2018 21:58:09 -0500 >> Bob kb8tq <kb8tq@n1k.org> wrote: >> >>> The same nickel plating effect gets into a lot of things. If you are shopping for very >>> low IMD connectors, nickel plating is out. Things get non-linear (to a very slight >>> degree) when it is present. If -180 db is the goal for those spurs, you might only >>> hit -120 db with the nickel connectors ….. >> >> Interesting. About what frequency range are you talking? > > UHF up into microwaves. It was part of a lecture back when I was in school … I > assume the basic physics hasn’t changed since then :) > Passive intermodulation distortion? What is the physics... hysteresis curves in the magnetization of the nickel is what I would suspect.

Hi > On Feb 23, 2018, at 6:17 PM, jimlux <jimlux@earthlink.net> wrote: > > On 2/23/18 1:33 PM, Bob kb8tq wrote: >> Hi >>> On Feb 23, 2018, at 4:23 PM, Attila Kinali <attila@kinali.ch> wrote: >>> >>> Hoi Bob, >>> >>> On Thu, 22 Feb 2018 21:58:09 -0500 >>> Bob kb8tq <kb8tq@n1k.org> wrote: >>> >>>> The same nickel plating effect gets into a lot of things. If you are shopping for very >>>> low IMD connectors, nickel plating is out. Things get non-linear (to a very slight >>>> degree) when it is present. If -180 db is the goal for those spurs, you might only >>>> hit -120 db with the nickel connectors ….. >>> >>> Interesting. About what frequency range are you talking? >> UHF up into microwaves. It was part of a lecture back when I was in school … I >> assume the basic physics hasn’t changed since then :) > > > Passive intermodulation distortion? What is the physics... hysteresis curves in the magnetization of the nickel is what I would suspect. > It turns out that the nickel’s really awful magnetic properties at RF get it into all sorts of problems. More or less, the issue is the non-linear field response in the vicinity of the nickel. You go from “reasonable skin depth” to “don’t go there” in zero distance when you hit the nickel plating. Past that it gets a bit complicated and it was a very long time ago …. Bob > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there.

-------- In message <2A6C14A0-823A-4177-AEFD-BED8BCEA887E@n1k.org>, Bob kb8tq writes: >It turns out that the nickel’s really awful magnetic properties at RF [...] The semiconductor industry has serious problems with electromigration of very tiny copper conductors. A large company in the business spent an awful lot of money failing to get Cobalt to work, before somebody said "But wait, isn't that one of the magnetic elements ?" It now seems to become Wolfram instead. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.