From: pcdhSpamMeSenseless@electrooptical.net   
      
   On 2026-01-26 11:48, john larkin wrote:   
   > On Tue, 27 Jan 2026 03:36:36 +1100, Bill Sloman    
   > wrote:   
   >   
   >> On 27/01/2026 2:53 am, john larkin wrote:   
   >>> On Sun, 25 Jan 2026 22:44:02 -0500, legg  wrote:   
   >>>   
   >>>> On Sun, 25 Jan 2026 08:08:48 -0800, john larkin    
   >>>> wrote:   
   >>>>   
   >>>>> On Sun, 25 Jan 2026 08:51:24 -0500, legg  wrote:   
   >>>>>   
   >>>>>> On Sat, 24 Jan 2026 19:25:35 +0000, liz@poppyrecords.invalid.invalid   
   >>>>>> (Liz Tuddenham) wrote:   
   >>>>>>   
   >>>>    
   >>>>>> In applications where power levels are important, pot core orientation   
   >>>>>> will affect 'N' in the flux density concentration, and produce early   
   >>>>>> saturation at the location where minimum x-sectional area occurs.   
   >>>>>>   
   >>>>>> RL   
   >>>>>   
   >>>>> That should have a small effect on my pulser. Ill try it.   
   >>>>>   
   >>>>> I got a 2% change in inductance when I rotated the core halves.   
   >>>>>   
   >>>>>   
   >>>>> John Larkin   
   >>>>> Highland Tech Glen Canyon Design Center   
   >>>>> Lunatic Fringe Electronics   
   >>>>   
   >>>> 2% FREE x-sectional area, and an indication that the previous   
   >>>> misalignment doesn't dominate minimum value.   
   >>>>   
   >>>> Mind you, you can get a similar change just by forcing out   
   >>>> the fluff and detritus present at the contacting surfaces.   
   >>>> That might be what you're actually seeing, even if the core   
   >>>> is gapped.   
   >>>>   
   >>>> In pot cores, minimum x-section usually occurs where the centre   
   >>>> core meets the top and bottom plates. In parts shapes designed   
   >>>> for power applications, this is usually corrected.   
   >>>>   
   >>>> This core rotation can be used as a tolerance trim, where   
   >>>> needed, but anything like that before impregnation is probably   
   >>>> just biting fart bubbles.   
   >>>   
   >>> Impregnation?   
   >>   
   >> Some people like to lock the windings and the leads in place with a   
   >> heavy layer of encapsulant. This works better if you put the part to   
   >> encapsulated under vacuum before you pour on the encapsulant.   
   >>   
   >> I've never seen it done, but I've heard about it. It's apparently very   
   >> messy.   
   >   
   > Wet stuff is messy, really nasty in production. In the case of a   
   > txline transformer made with a few turns of coax, there's no reason to   
   > pot it.   
   >   
   > We just spin a few turns on a bobbin and clamp it into the pot core.   
   > If it got sloppy, a tie-wrap would secure things.   
   >   
   > Some people like the idea of potting things. Weird.   
      
   Last year we did a TDR that had to survive being pounded into hardpan   
   with a slide hammer (>20k gees).  Potting was the right answer there!   
      
   We put in small bits of foam sticky tape to keep the epoxy from trashing   
   the pulse shapes.  If we did it again, we'd probably go to a six-layer   
   board and use stripline to avoid the problem (mostly).   
      
   Cheers   
      
   Phil Hobbs   
      
   --   
   Dr Philip C D Hobbs   
   Principal Consultant   
   ElectroOptical Innovations LLC / Hobbs ElectroOptics   
   Optics, Electro-optics, Photonics, Analog Electronics   
   Briarcliff Manor NY 10510   
      
   http://electrooptical.net   
   http://hobbs-eo.com   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)