> ## I agree, if it's just for a 50 ohm choke balun.... just use teflon
> coax. like RG-393/400/303... and either
> wrap it around type 43/31 cores... or slide large diam type 43/31 beads
> over the coax,
> and be done with it.
That's my take after reading Sevick's Fourth ed. If it's a 1:1 choke with a
reasonably-controlled low to moderate Z on the load side of the balun, then
for HF, I would lean toward coax on a #31 core.
OTOH, if a 1:1 or 1:4 current balun were feeding a balanced transmission
line from an ATU (e.g., an 80m 1/2-wave c.f. dipole operating at 7 MHz with
a half-wave of balanced open line), then I would lean toward a bifilar
choke, using Teflon over enameled Formvar wire. In the latter case, the
voltage across the load side of the balun can reach 3KV+ at 1.5KW. No doubt
several small diameter coaxial cables can handle it, but I would still favor
enameled wire. However, if I'm reading Sevick's data correctly, losses at
30 MHz and above typically appear to be higher with a bifilar choke over
that of a coaxial W1JR type (with or without crossover).
Paul, W9AC
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