75 Ohm Coax

75 Ohm Coax for Amateur Radio

Know Your Cable
Shielding
Quad shield (two foil + two braid layers) — best RFI rejection, worth seeking out. Dual shield (foil + braid) — adequate for most installations. Single braid — generally avoid if you have a choice.
Center Conductor
Most CATV RG-6 uses copper-clad steel — fine on 20m and above, but higher loss on 80m and 160m due to skin depth. Solid copper center conductor is available and preferred for lower HF bands.
RG-6 vs RG-59
RG-6 — larger center conductor, lower loss, better shielding options. The go-to choice.
RG-59 — thinner, higher loss, but still usable for short runs. If it's free or dirt cheap, it works — just know the tradeoffs.
Salvaged Cable
Old cable TV runs can be perfectly good — inspect for physical damage, cracked jackets, or corroded connectors. When in doubt, cut off the ends and re-terminate.