I've found the super-flex insulated 'antenna wire' sold by Davis RF is
pretty good for winding larger ferrite cores (bifilar, quadfilar, ...).
Also I've repeatedly used RG-142 Teflon coax for winding chokes. It's high
power silver coated 50-ohm coaxial cable about the same outer diameter as
RG-58.
No connection to Davis RF other than use their products.
http://www.davisrf.com/amateur.php
Dave - WØLEV
On Tue, Jan 21, 2020 at 9:43 PM Grant Saviers <grants2@pacbell.net> wrote:
> It could happen, but I've not experienced it. It was a problem with TFE
> insulated wire wrap if the wire route was very tight to a post. The
> spec on posts was 0.002" maximum corner radius and I've never seen
> anything that sharp on ferrite cores.
>
> Another factor is it is pretty difficult to get a very tight wrap with
> RG400 or #12. If concerned, then 1/4" or 3/8" wide kapton tape wrap of
> the core is a choice. Or diamond file any rough spots.
>
> IIRC, Fair-Rite also offers optional epoxy coatings for most all
> products, but I've never seen that for #31 cores in stock.
>
> Grant KZ1W
>
> On 1/21/2020 12:47, K9MA wrote:
> > Back in my spacecraft hardware building career, it was well known that
> > Teflon would "cold flow". Great care was taken where wires went around
> > corners, etc., that there was no pressure on the insulation. Has anyone
> > heard of such issues with chokes?
> >
> > 73,
> > Scott K9MA
> >
> >
> > On 1/21/2020 12:21, Jim Brown wrote:
> >> On 1/21/2020 9:32 AM, EDWARDS, EDDIE J via RFI wrote:
> >>> Use coaxial cable when making RF chokes for antenna systems.
> >>
> >> Parallel wires work fine for winding chokes. There's no need for
> >> shielding -- the field from the choke is confined to the core.
> >>
> >> At least half of the chokes in my station are wound with a pair of
> >> Teflon insulated #12 stranded silver-coated copper wire. The rest are
> >> wound with RG400. The Cookbook includes data for #12 THHN as a lower
> >> cost alternative.
> >>
> >> http://k9yc.com/2018Cookbook.pdf
> >>
> >> 73, Jim K9YC
> >> _______________________________________________
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> >> RFI@contesting.com
> >> http://lists.contesting.com/mailman/listinfo/rfi
> >
> >
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--
*Dave - WØLEV*
*Just Let Darwin Work*
*Just Think*
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