Stop Using Bare Copper on Your Antennas: Do This Instead

If you want antenna systems that just keep working, year after year, the short bits of wire between tuner, balun and antenna are the last place to save a few cents.

The short version: use tinned, stranded copper wire with a PTFE (Teflon) sleeve for those exposed connections. It survives weather, heat, RF voltage and flexing far better than bare “pure” copper, speaker wire, or anything just wrapped in electrical tape.

What those “little” bits of wire are really dealing with

The jumpers between tuner, balun and antenna terminals live in a nasty world:

• Outdoors in rain, UV, pollution and temperature swings
• Often carrying very high RF voltages at the tuner / balun end
• Subject to movement and vibration from wind and feedline motion
• Full of RF current that flows mainly on the surface of the metal (skin effect)

So the material and insulation matter a lot more than they would for, say, indoor loudspeaker leads.

Why tinned, stranded copper is ideal

Tin stops the copper from eating itself

Plain copper is reactive. In air and moisture it quickly forms oxides and carbonates (the familiar brown/green tarnish) that increase resistance and eventually pit and weaken the conductor.

A thin tin coating acts as a sacrificial barrier between the copper and the environment:

• Tin-plated (tinned) copper wire is widely used in marine cable specifically because it resists corrosion from moisture and salt, dramatically extending service life.
• The tin layer keeps oxygen and salts away from the copper, so the strands don’t turn black and crumble inside the insulation over time.

This is precisely what you want on a mast or at a balun hanging in the rain: the copper stays copper instead of turning into a high-resistance science experiment.

Stranding stops the wire from breaking

Those leads see constant micro-movement from wind, feedline sway and thermal expansion. Solid copper work-hardens and eventually snaps, usually right at the connector.

Stranded conductors:

• Tolerate repeated bending and vibration far better than solid copper
• Distribute mechanical stress along many fine strands instead of one solid bar
• When each strand is individually tinned, corrosion can’t creep between strands as easily as with bare stranded copper.

Result: the wire doesn’t mysteriously break the first time you get an ice storm and a bit of wind.

Better RF behavior and solderability

At RF, current flows in a thin “skin” at the surface of the conductor. That means the condition of the surface is everything:

• A clean metal surface (tin, silver, copper, etc.) is a good conductor
• A thick oxide layer is not – it adds resistance and heating, and causes lousy, noisy contacts

RF hardware is often plated (silver, tin, gold) for exactly this reason.

Tin plating also stays solderable for years; bare copper that’s lived outdoors usually needs scraping or abrasion before it will wet properly.

Why PTFE insulation is the “good stuff”

PTFE (Teflon) insulation around that tinned, stranded copper is the second half of the “bomb-proof” recipe.

Low loss at RF

PTFE has:

• Very low dielectric constant (around 2.1)
• Very low loss factor, and those properties hardly change with temperature, humidity, or frequency

That’s why PTFE is a go-to material for high-performance coax and RF cables – it keeps dielectric loss and detuning to a minimum.

Handles heat and RF voltage

PTFE:

• Is typically rated up to around +200–260 °C (depending on grade)
• Shrugs off soldering irons and hot components
• Has very high dielectric strength – great for the high RF voltages that can appear at tuner and balun terminals

That means less chance of insulation melting, carbonizing, or tracking over when you’re running power on a wet day.

Weather, chemicals and UV don’t scare it

PTFE is famously inert:

• Resistant to UV, moisture, oils and many chemicals
• Remains flexible and doesn’t embrittle or crack with age the way many plastics do

So while clear PVC speaker-wire jackets go hard, cloudy and split after long sun exposure, PTFE just keeps on being PTFE.

Why “pure” bare copper is a bad long-term choice here

Electrically, copper is excellent. That’s why it’s inside almost all decent coax. The problem is bare copper exposed to the weather at terminals and jumper leads.

Oxidation + RF skin effect = trouble

Copper exposed to air and moisture forms an oxide and carbonate layer.

Combine that with skin effect (RF current flowing mostly at the surface) and you get:

• Higher series resistance
• More heating and loss in the conductor
• Flaky, intermittent contacts at lugs and clamps

At HF and up, you are depending on the outer few tens of microns of the metal. If those microns are a crusty layer of crud, your Q and efficiency suffer.

Corrosion creeps into the cable

With untinned stranded copper:

• Moisture wicks along the gaps between strands via capillary action
• The inner strands oxidize out of sight
• You end up with a cable that looks fine from the outside but has lost a big chunk of its conductive cross-section

Marine and outdoor cable specs are designed to fight this; hence tinned stranded copper is standard in marine wire.

Mechanical weakness and work-hardening

Bare solid copper, especially “mains” house wire, is:

• Relatively soft
• Easily work-hardened by bending
• Prone to snapping after repeated flexing at a terminal, especially in the cold

That’s why serious outdoor antennas often use copper-clad steel or other reinforced conductors for long spans. Stranded tinned copper is a more flexible, jumper-friendly answer to the same problem.

Speaker wire and electrical tape: why they’re not a long-term solution

Speaker wire: made for living rooms, not masts

Common “zip cord” speaker wire is designed for indoor, low-voltage audio, not outdoor RF service.

Typical issues:

• Random conductor material. Many low-cost speaker cables are copper-clad aluminium (CCA), not pure copper – cheap and light, but higher resistance and lower strength.
• Jacket not intended for years of weather. The flexible PVC used on many speaker cables is optimized for indoor use. Standard PVC insulation is susceptible to UV degradation, hardening and cracking under prolonged sunlight and heat, unless specially UV-stabilized.
• Not a controlled transmission line. Speaker wire is just two conductors in a jacket. As RF feedline between tuner and antenna, it has non-standard and poorly controlled impedance (often somewhere around 100 Ω, but it varies) and unknown velocity factor.
• Voltage rating & insulation thickness. Speaker cable insulation is sized for a few tens of volts of audio, not the hundreds or thousands of volts RF that can appear at a tuner output on a mismatched load.

So yes, speaker wire can “work” as a temporary antenna or jumper. Lots of people have made contacts that way. But it’s not something you can install, forget, and trust through winters, storms and power.

Why just taping over bare copper isn’t enough

Wrapping bare copper or house wire in electrical tape is a band-aid, not a cure:

• Standard PVC insulation tape is moisture-resistant, not waterproof. It won’t reliably keep water out over the long term; adhesives soften and let moisture creep in.
• Many PVC tapes (and non-UV-rated tapes in particular) are prone to UV degradation, becoming brittle and cracking in sunlight.
• Even manufacturers and distributors note that electrical tape is suitable only for short-term or limited permanent repairs, not as a primary cable jacket.

So when you “waterproof” a bare copper joint with a few turns of generic tape, you’re really just delaying water ingress and corrosion by a season or two. After that, the adhesive oozes, the tape unwraps, UV cracks it, and the joint starts to rot.

Proper outdoor terminations use things like:

• Adhesive-lined heat-shrink tubing, or
• Self-amalgamating rubber tape with a UV-resistant outer wrap

…over a mechanically sound, corrosion-resistant conductor — not instead of one.

What to actually buy and use

For the short leads between tuner, balun and antenna terminals, look for something like:

• Conductor: tinned, stranded copper (marine-grade or PTFE hookup wire). Each strand individually tinned is ideal.
• Insulation: PTFE (or another fluoropolymer like FEP/PFA); many vendors market this as “PTFE hookup wire” or “Teflon-insulated wire” with a wide temperature range and excellent RF properties.
• Size: roughly 12–14 AWG (2–4 mm²) for typical HF power levels, heavier if you’re running high power and very long jumpers.

Use proper crimp lugs or soldered eyelets, then seal the junction with heat-shrink or self-amalgamating tape plus a UV-resistant outer wrap. Don’t forget strain relief so the connection isn’t flexing right at the terminal.

Bottom line

• Bare “pure” copper in the weather is a consumable, not a permanent solution. It oxidizes, corrodes and fatigues mechanically.
• Speaker wire and taped joints are fine for experiments, but they’re not designed for long-term outdoor RF duty — wrong material, wrong insulation, wrong ratings.
• Tinned, stranded copper with PTFE insulation is purpose-built to survive the exact abuse your tuner–balun–antenna wiring sees: RF, weather, heat, movement and time.

Build those short connections once with the right wire and proper sealing, and you stop climbing the mast to chase “mystery” SWR issues — you can spend that time on the air instead.

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