Have you thought of using a 1:1 balun of the guanella type? I built mine
using RG400 and one core. No signs of problems at the legal limit and
2:1 SWR.
-John NI0K
Jim Brown <mailto:jim@audiosystemsgroup.com>
Sunday, January 28, 2018 8:02 PM
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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