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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