[TowerTalk] Voltage Breakdown For Enameled Wire

[Mike & Becca Krzystyniak]

Hi Jim,

   As you probably know a Class 3 insulator material is best.
   Some enamels work well at 105C temps, FormVAR variants etc...
   If you think it will run hotter there are materials that go a lot
higher,but the price scales with it.

   I lucked into a roll of #12 Class 3 using a bondable formVAR.
   Tough stuff and very hard to scratch or crack when bending. 
   I use it in Hybrids and baluns.  It can take the voltage even when
tightly winding it (no holes or cracks).
   But I still tape the cores too.

Mike  K9MK



-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Jim
Brown
Sent: Sunday, January 28, 2018 8:03 PM
To: towertalk reflector
Subject: [TowerTalk] Voltage Breakdown For Enameled Wire

I'm once again considering winding high power chokes with enameled wire. 
Zo of a closely #12 pair is about 53 ohms, which makes it desirable IF
breakdown voltage is sufficient. I would appreciate for sources of #10 or
#12 enameled wire with published breakdown specs.

I've found that THHN (about 93 ohms Zo) works fine for simple antennas like
dipoles, but some multiband antennas with complex matching/coupling systems
don't like that much mismatch. We had this problem with the Force 12 C3SS,
the choke is enameled #12 of unknown pedigree. No breakdown issues with a
600W power amp and the antenna is a good match to it, but the engineer in me
wants to be conservative for legal limit to an 80/75 dipole that I use from
3.5-3.9 MHz.

Yes, I know I could put the conductors in Teflon tubing, but that increases
Zo. I've measured #12 pairs with various Teflon insulation and get values
around 101 ohms at HF.

Suggestions?

73, Jim K9YC


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