In searching I see a variety of 50 ohm coax types being used in various ferrite toroid/bead CM choke designs. Is there any electrical significance to which type of 50 ohm coax is used or is it solely a physical concern, small enough to fit closely to the ferrite, bends enough, will support the number of turns though the toroid that are needed?
Electrically, type does not matter, as long as it is of reasonable quality. -"Minimum Bending Radius" is a key limiting factor for any coax to avoid damage and compromising impedance, shorting and RF leakage. Refer to manufacturer's spec sheet. Don't "assume" one radius spec applies across any give coax type.
Avoid coax with the soft, PE, thermoplastic center conductor. It can short the center conductor to the inside of the shield.
As long as Minimum Bend Radius and Power/Heat Dissipation ratings are not exceeded, there is no reason such coax cannot be used.
I would just use the Teflon stuff, like RG-303 or RG-400. I have a spool of slightly smaller white, Teflon, 50 Ohm coax that looks like this when wound onto a 2.4inch core.
A stranded center is key to not deforming the coax. I bought a short spool of RG400 just for baluns. Ed
