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Re: new X-chapters

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Am 25.02.26 um 04:44 schrieb john larkin:

> You are using fancier connectors with tiny center pins. I'm using the
> really cheap, under $2, ones with giant round center pins. An e/m sim
> says that the pin alone, not on a board, is about 100 ohms.

One can see the influence of the SMA center connector on the picture
of the solder-friendly board on the unpopulated side. The dip is by
far not as severe.
> 
> Why do people make such a big deal over right-angle trace bends? I've
> never seen one on my 30 ps TDR.

I wanted to make sure that I don't ask for trouble if I meander
from a ball grid array.

> I cut away all the planes under the connector center pin and pave over
> the bottom side with copper. That just about works.

... but have enough gnd vias around. *ON* the board it's layer L2 that
counts for GND.
> 
> Most of the JLCPCB  4 and 6-layer stacks have absurdly thin L1-L2
> dielectrics. A couple have double prepreg, thicker dielectric, so let
> you make fatter traces, like 20 mils for 50 ohms. Less loss.

For a NMR project on 8 GHz, I had a mixed Rogers TMM-6 & FR4 board.
Not from JLCPCB but the customer's favourite shop around the corner.

The strip lines ended up on the FR-4 side, power supply on TMM_6.
Yes, we *had* talked about the stackup. It's clearly the best not to
expect people thinking or to deviate from their daily routine.

BTW, TMM-6 is a brittle, ugly material which feels much like an
eraser gum. I would not use it alone without FR4 for mechanical reasons.


We used to build oil/gaz pipeline pigs. FR4 may soak up hydrocarbons
and swell. That may crack the vias open. So we went to boards made
from Kapton.

Be alarmed when the factory offers short production times. Kapton
prepregs have a shelf live of only a few weeks. They may be tempted
sell you prepregs that are left over from a project half a year ago.
Your boards will de-laminate after two weeks in the field.
Been there, seen that, with luxury top notch FPGAs that cost 1000s. :-(


cheers, Gerhard

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new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-21 10:43 -0800
  Re:new X-chapters Martin Rid <martin_riddle@verison.net> - 2026-02-21 15:25 -0500
    Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-23 11:00 -0800
      Re: new X-chapters Joe Gwinn <joegwinn@comcast.net> - 2026-02-23 14:39 -0500
        Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-23 14:25 -0800
          Re: new X-chapters JM <sunaecoNoChoppedPork@gmail.com> - 2026-02-23 22:42 +0000
            Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-23 14:54 -0800
              Re: new X-chapters Joe Gwinn <joegwinn@comcast.net> - 2026-02-23 20:17 -0500
                Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-23 19:18 -0800
                Re: new X-chapters Bill Sloman <bill.sloman@ieee.org> - 2026-02-24 17:27 +1100
                Re: new X-chapters Joe Gwinn <joegwinn@comcast.net> - 2026-02-24 14:01 -0500
      Re: new X-chapters Lasse Langwadt <llc@fonz.dk> - 2026-02-23 23:23 +0100
        Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-23 19:19 -0800
          Re: new X-chapters Bill Sloman <bill.sloman@ieee.org> - 2026-02-24 17:32 +1100
      Re: new X-chapters Joerg <news@analogconsultants.com> - 2026-02-24 14:53 -0800
        Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-24 15:57 -0800
          Re: new X-chapters Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2026-02-24 19:12 -0500
            Re: new X-chapters "Edward Rawde" <invalid@invalid.invalid> - 2026-02-24 21:04 -0500
              Re: new X-chapters JM <sunaecoNoChoppedPork@gmail.com> - 2026-02-25 02:25 +0000
                Re: new X-chapters "Edward Rawde" <invalid@invalid.invalid> - 2026-02-24 22:28 -0500
                Re: new X-chapters John R Walliker <jrwalliker@gmail.com> - 2026-02-25 08:46 +0000
                Re: new X-chapters liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-02-25 09:39 +0000
                Re: new X-chapters JM <sunaecoNoChoppedPork@gmail.com> - 2026-02-26 00:12 +0000
              Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-25 04:15 -0800
                Re: new X-chapters liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-02-25 14:04 +0000
                Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-25 07:58 -0800
                Re: new X-chapters liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-02-25 19:31 +0000
                Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-25 14:13 -0800
                Re: new X-chapters liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-02-25 22:51 +0000
                Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-25 16:30 -0800
                Re: new X-chapters liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-02-26 09:57 +0000
                Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-26 08:22 -0800
                Re: new X-chapters Bill Sloman <bill.sloman@ieee.org> - 2026-02-27 03:51 +1100
                Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-26 09:03 -0800
                Re: new X-chapters Bill Sloman <bill.sloman@ieee.org> - 2026-02-27 17:04 +1100
                Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-27 03:45 -0800
                Re: new X-chapters Bill Sloman <bill.sloman@ieee.org> - 2026-02-28 03:56 +1100
                Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-27 10:18 -0800
                Re: new X-chapters Bill Sloman <bill.sloman@ieee.org> - 2026-02-28 17:29 +1100
                Re: new X-chapters Bill Sloman <bill.sloman@ieee.org> - 2026-02-26 22:51 +1100
                Re: new X-chapters Bill Sloman <bill.sloman@ieee.org> - 2026-02-26 22:49 +1100
                Re: new X-chapters Bill Sloman <bill.sloman@ieee.org> - 2026-02-26 22:44 +1100
                Re: new X-chapters Glen Walpert <nospam@null.void> - 2026-02-25 18:44 +0000
                Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-25 14:24 -0800
                Re: new X-chapters Jan Panteltje <alien@comet.invalid> - 2026-02-26 07:11 +0000
            Re: new X-chapters Jan Panteltje <alien@comet.invalid> - 2026-02-25 06:52 +0000
              Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-25 09:58 -0800
                Re: new X-chapters Jan Panteltje <alien@comet.invalid> - 2026-02-26 07:06 +0000
                Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-26 08:32 -0800
                Re: new X-chapters Jan Panteltje <alien@comet.invalid> - 2026-02-26 17:52 +0000
                Re: new X-chapters Bill Sloman <bill.sloman@ieee.org> - 2026-02-27 17:26 +1100
                Re: new X-chapters Jan Panteltje <alien@comet.invalid> - 2026-02-27 13:31 +0000
                Re: new X-chapters liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-02-27 09:48 +0000
                Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-27 10:15 -0800
                Re: new X-chapters Bill Sloman <bill.sloman@ieee.org> - 2026-02-28 05:20 +1100
                Re: new X-chapters Jeroen Belleman <jeroen@nospam.please> - 2026-02-27 21:09 +0100
                Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-27 20:01 -0800
                Re: new X-chapters Gerhard Hoffmann <dk4xp@arcor.de> - 2026-02-28 10:22 +0100
                Re: new X-chapters Bill Sloman <bill.sloman@ieee.org> - 2026-03-01 01:08 +1100
                Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-28 07:51 -0800
                Re: new X-chapters Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2026-02-28 12:48 -0500
                Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-28 10:07 -0800
                Re: new X-chapters liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-02-27 21:02 +0000
                Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-27 14:28 -0800
                Re: new X-chapters Bill Sloman <bill.sloman@ieee.org> - 2026-02-28 17:38 +1100
                Re: new X-chapters Gerhard Hoffmann <dk4xp@arcor.de> - 2026-02-28 10:17 +0100
                Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-28 07:52 -0800
                Re: new X-chapters Jim Jackson <jj@franjam.org.uk> - 2026-02-28 22:35 +0000
                Re: new X-chapters Jim Jackson <jj@franjam.org.uk> - 2026-02-28 12:30 +0000
                Re: new X-chapters Bill Sloman <bill.sloman@ieee.org> - 2026-02-28 23:53 +1100
                Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-28 07:53 -0800
                Re: new X-chapters liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-03-01 19:58 +0000
                Re: new X-chapters Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2026-03-01 20:16 +0000
                Re: new X-chapters liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-03-01 21:37 +0000
                Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-03-01 13:43 -0800
                Re: new X-chapters antispam@fricas.org (Waldek Hebisch) - 2026-02-28 14:07 +0000
        Re: new X-chapters Joe Gwinn <joegwinn@comcast.net> - 2026-02-24 20:15 -0500
  Re: new X-chapters Joerg <news@analogconsultants.com> - 2026-02-21 14:10 -0800
    Re: new X-chapters ehsjr <ehsjr@verizon.net> - 2026-02-22 10:15 -0500
      Re: new X-chapters Joerg <news@analogconsultants.com> - 2026-02-24 12:34 -0800
        Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-24 16:12 -0800
          Re: new X-chapters Gerhard Hoffmann <dk4xp@arcor.de> - 2026-02-25 01:42 +0100
            Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-24 19:44 -0800
              Re: new X-chapters Gerhard Hoffmann <dk4xp@arcor.de> - 2026-02-25 11:28 +0100
                Re: new X-chapters john larkin <jl@glen--canyon.com> - 2026-02-25 03:57 -0800

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