My good friend David Cripe (NMOS) has recently informed me about a new product he’s offering to the radio community via his eBay store: Kev-Flex Stealth Kevlar Antenna Wire. Kev-Flex looks like a superb option for field antennas of all stripes especially since it has an incredibly high tensile strength. It’s available in 75′ bundles, but Dave can also cut custom lengths. NM0S is also a trusted retailer in the ham radio world, so you can purchase with confidence.
Here’s the product description and link:
Kev-Flex is a unique antenna wire manufactured exclusively for NM0S Electronics. The lightweight center core of the wire is made from Kevlar fiber, giving the wire its incredible strength. The Kevlar core is wrapped with six tinned strands of 30 AWG copper. The effective surface of the wire creates an effective skin area capable of handling well over 100W.
The cable is protected from the elements by a coating of UV-resistant black polyethylene. With a total diameter of only 1/16″ (incl. insulation) and a weight of just 16 feet per ounce, the tensile strength 125 lbs allows lengthy unsupported horizontal runs. Kev-Flex is ideal for extremely long LW-antennas and Beverages and is great for balloon or kite-supported antennas. Its low weight and high break-load makes it most suitable for SOTA activations and other field operations.
The outer insulation makes the wire kink-resistant, and its slippery finish makes it ideal for stealth antennas that must be passed through trees or other obstacles without snagging.
This antenna wire is sold in 75 foot long bundles, which is enough for a 40M dipole or EFHW. Two 75 foot bundles would make a great 80M dipole. Custom lengths are available on request.
Specification
– Kevlar fiber core wrapped with six 30 AWG copper strands
– Weather-proof black polyethylene (PE) insulation, 1/16″ O.D.
– Weight: 16 feet per ounce
– Breaking-load: 125 lbs
– Velocity factor 0.97
How do I crimp this wire, with the fiberglass-ish stuff in the crimp or no?
Strip 2-3 inches more than you need, roll back the wire and cut the thread out about 2/3 the way back. Wrap the wire around the thread to maintain tensile strength and crimp it together ensuring the conductor is in total contact with the lug. Another option is to wrap the conductor around the thread trying to completely cover the thread and try to thread the kevlar material through the lug opening, crimp it and then trim of the excess material. Just a few suggestions that come to my simple little mind
“Velocity factor 0.97”
Hmm… wonder how they managed to come to that number? Velocity factor is only applicable to transmission lines i.e. multiple conductive elements. A single conductive element – even one wrapped around or surrounding a dielectric – by definition doesn’t have a velocity factor (well, at least until you get into the microwave, where coils start behaving like waveguides & strange things happen – and even there…).
Maybe they measured it sitting on a metal table? 😉
FWIW very similar stuff has been around for years, commonly called ‘Clansman’ or ‘NATO’ wire. Wound or woven conductor around a stranded kevlar core, olive-green PTFE or PVC outer, in a variety of sizes from 1.5mm up. Bought 100m about 15 years ago for ~AU$1/m.
Even your antenna elements have a “Velocity factor 0.97”, use this number when estimating element length…
Is the 0.97 factor due to the copper wrapped in a spiral around the Kevlar core making the copper wire roughly 3% longer than the actual Kevlar length?
Are you planning to set up some wire antnna, by chanche ? 🙂