How to Install a CB Antenna on a Kenworth T680

How to Install a CB Antenna on a Kenworth T680

The Kenworth T680 is one of the most common Class 8 trucks on the road, and it's also one of the more challenging platforms to install a CB or 10 meter antenna on because of its aerodynamic cab, composite-panel mirrors, and heavily insulated interior. This guide walks through a mirror-mounted install — the most popular, reliable, and repeatable option on the T680 — using parts we stock, ship same-day, and hand-tune before they leave Indiana.

By the end you'll have a properly grounded, low-SWR antenna installed on your T680 in about 45 minutes with basic hand tools.

What you'll need

• Antenna: Stryker SR-A10 — 49" stainless whip, 10-gauge silver-plated copper coil, handles 10,000W. Purpose-built for the T680 mirror-mount install. Alternatives: any 4-foot to 8-foot mirror-mount whip with a SO-239 stud.
• Mount: DRX-3402 double-slotted heavy-duty mirror mount — bolts directly to the T680's factory mirror arm bracket, no drilling.
• Coax: DRX-1518 18-foot M213 premium coax — long enough for the passenger-side run and short enough to avoid coiling penalty at the radio. 18 feet is the sweet spot for a T680 with an under-bunk or in-dash radio.
• Radio: Any of the Stryker 10 meter radios (SR-447HPC2, SR-497HPC, SR-655HPC+, or SR-955HPC+) or a Part 95 CB radio.
• SWR meter or analyzer — required for the final tune. See our SWR tuning guide if you're new to the process.
• Tools: 9/16" and 1/2" wrenches, Phillips screwdriver, wire cutters, tape measure.

Why a mirror mount on the T680

The T680's fiberglass roof and composite hood are poor grounding surfaces for an antenna. The factory West Coast mirror arm bracket, on the other hand, is bolted directly to the door hinge assembly and grounded through the cab frame — an excellent RF ground plane. A properly installed mirror mount on the T680 will consistently return lower SWR readings (under 1.5:1) than a magnet mount or roof mount on the same truck.

Other advantages:

• No drilling — bolts to the factory mirror arm bracket at the base of the mirror head.
• Serviceable at rest stops — the antenna can be swapped or the coax replaced without pulling interior panels.
• Fits both driver and passenger side. Passenger side is preferred for a single-antenna install because the coax run is shorter to a right-hand dash radio and the antenna clears low overhangs at truck stops.

Step-by-step install

Step 1 — Locate the mirror arm bracket

Open the passenger door and find the vertical mirror arm where it meets the door frame. The DRX-3402 mounts to the flat portion of the bracket between the mirror arm and the door skin. You'll see two factory bolts holding the arm to the cab — leave those alone. The DRX-3402 comes with its own bolt hardware that clamps over the bracket without touching the factory fasteners.

Step 2 — Install the DRX-3402 mirror mount

Position the DRX-3402 on the mirror arm bracket with the SO-239 stud pointing up. Thread the two mounting bolts through the double-slotted plate and into the mounting saddle on the back of the bracket. Snug both bolts with a 9/16" wrench — don't fully torque yet. The double-slotted design lets you shift the mount up or down by about 3/4" so the antenna clears the top of the mirror head; adjust now, then torque both bolts to about 15 ft-lb.

Step 3 — Thread the antenna onto the mount

Screw the SR-A10 (or your chosen antenna) onto the SO-239 stud until snug. Do not overtighten — hand-tight plus a quarter turn with a wrench is enough. The stainless whip should sit vertically with the coil about 4–6 inches above the top of the mirror head. If the whip hits the mirror head as it flexes at highway speed, reposition the mount lower using the slot adjustment from Step 2.

Step 4 — Route the coax

Run the DRX-1518 coax from the antenna base down along the mirror arm, into the door jamb through the factory rubber grommet at the base of the A-pillar, then along the floor sill toward the radio. Route:

• Down the mirror arm — zip-tie the coax to the arm every 6 inches so it doesn't flap.
• Through the passenger A-pillar grommet — the T680 has a factory rubber pass-through here; feed the PL-259 connector through first, then pull the coax through until only the amount you need at the antenna base is left outside.
• Under the passenger-side dash pad — the T680 has a wire tray under the dash pad that will accept the coax without visible routing.
• Down to the radio location — most operators mount the radio in the overhead cubby, under the passenger dash, or on a floor console. Leave 12–18 inches of service loop at the radio end so you can pull the radio out for service without disconnecting.

Step 5 — Do NOT coil excess coax

If you have extra coax at the radio end, cut it and re-terminate with a new PL-259, or use a shorter run. Coiling excess coax creates a choke that raises SWR and can cause RF feedback into the truck's electronics. The DRX-1518 is 18 feet for a reason — that's the electrical length that resonates cleanly on a T680 install without needing to be trimmed.

Step 6 — Connect the radio and tune

Connect the PL-259 to the radio's antenna jack finger-tight plus a quarter turn. Power on the radio. Hook up an SWR meter inline between the radio and the antenna. Key up briefly on the middle of your operating range (channel 20 for CB, or 28.400 MHz for 10 meter) and read SWR. Adjust the SR-A10 tip length until SWR is under 1.5:1. Under 2.0:1 is safe to run. Full tuning walkthrough in our CB antenna tuning guide.

Step 7 — Weatherproof the connection

Wrap the antenna's SO-239-to-PL-259 connection at the mount with self-fusing silicone tape (not electrical tape). This keeps water out of the coax over-winter and prevents SWR drift from moisture ingress.

Common T680 install mistakes

• Mounting on the fiberglass roof. The T680's roof is not a ground plane. Every antenna mounted directly to the roof of a T680 will read high SWR and radiate poorly, regardless of tuning.
• Running coax through the door. The door pinches the coax every time it closes. Use the A-pillar grommet, not the door seal.
• Coiling excess coax under the seat. Cut the coax to length, don't coil it.
• Skipping the SWR check. A stock-length whip will almost always need to be trimmed 1/4" to 1" for the specific truck. Skipping the SWR tune means running high SWR and stressing the radio's finals.
• Using RG-58 coax. RG-58 works but has 30% more loss per foot than RG-8X or M213 at CB and 10 meter frequencies. The DRX-1518 M213 coax delivers noticeably more clean power to the antenna over an 18-foot run.

Two-antenna (co-phase) install on the T680

If you want to run co-phase antennas on both mirrors of a T680, you need two matched mirror-mount whips (both SR-A10s, or another matched pair of mirror-mount antennas like Wilson 5000 Truckers or Firestik FS-4s), two mirror mounts, and a co-phase harness cut to spec. Co-phase gains 3 dB of forward gain but is directional along the truck's long axis. Ask us before you order — a co-phase install on a T680 needs matched spacing and a matched pair of whips to work correctly. Email info@cbradiosupply.com or call and we'll walk you through parts selection.

FAQ

What's the best CB antenna for a Kenworth T680?

The Stryker SR-A10 on a DRX-3402 mirror mount. It's rated for 10,000 watts, uses a silver-plated copper coil for low loss, ships with a 2-year warranty, and mounts cleanly to the T680's factory mirror bracket without drilling.

Do I need to drill holes in my T680 to install a CB antenna?

No. The DRX-3402 double-slotted mirror mount bolts to the factory mirror arm bracket with its own hardware. There is no drilling required. The install is fully reversible if you sell the truck.

How long should my coax be on a T680 install?

18 feet. That's why we spec the DRX-1518 18-foot M213 coax — it's the electrical length that resonates cleanly for a mirror-mount install on most Class 8 trucks including the T680, and it reaches the common radio locations (overhead cubby, passenger dash, floor console) without needing to coil.

Can I install a magnet mount on a Kenworth T680 instead?

Yes, but the T680's fiberglass roof isn't a ground plane, and a mag mount on the fuel tank or hood will read higher SWR than a mirror mount. If you need a temporary or removable install, use the SR-A10MM magnetic mount on a metal panel (fuel tank cover, tool box lid). For a permanent install, the mirror mount is better.

Where should I mount the radio in a T680?

Three good locations: (1) overhead cubby above the driver — great for Stryker SR-447HPC2 or SR-655HPC+ short-chassis radios; (2) under the passenger dash on a swivel mount — works for full-size chassis like the SR-497HPC or SR-955HPC+; (3) floor console — works for any radio but the mic cord run is longer.

Do I need an FCC license to run this setup on a T680?

Depends on the radio. CB radios (Part 95) require no license. 10 meter radios like the Stryker SR-447HPC2, SR-497HPC, SR-655HPC+, and SR-955HPC+ require an FCC Amateur license (Technician class minimum). See our 10 meter radio licensing guide for the full details.

What SWR should I be reading after this install?

Under 1.5:1 on your primary operating frequency is excellent. Under 2.0:1 is safe to run. Anything over 2.5:1 means the antenna is mis-tuned or there's an issue with the coax, connector, or mount — stop, troubleshoot, and re-check before continuing to transmit.

Can I use this same install on a T880, W900, or Peterbilt 579?

Yes, with minor variations. The DRX-3402 mount fits every Kenworth and Peterbilt West Coast mirror arm we've tested. The coax routing is nearly identical on the T880 and W900. On the Peterbilt 579, the A-pillar grommet is smaller and you may need to feed the PL-259 through separately from the coax.

Ready to build your kit

The full T680 install kit — SR-A10 antenna, DRX-3402 mirror mount, DRX-1518 18-foot M213 coax — pairs with any Stryker 10 meter radio. Shop the Stryker 10 meter radios collection and add the accessories at checkout, or contact us and we'll build a matched combo for you.

Don't forget to add the Pro Tune & Alignment option at checkout so your radio is professionally bench-tuned for best performance per the manufacturer's service manual.