Instructions for 80-10 Hybrid Dipole by KB5WVK
Materials Needed
- Wire: 92 ft of 14–18 AWG stranded copper or copper-clad steel (~$10, e.g., Amazon, DX Engineering).
- Ladder Line: 40 ft of 450-ohm window line (~$20, e.g., DX Engineering, ~$0.50/ft).
- Capacitor: 500 pF, 1 kV ceramic capacitor (for 20W; ~$1–$2, e.g., Mouser, DigiKey, eBay).
- Balun: 1:1 current balun, 100W rating, mix 31 ferrite (~$20–$30, e.g., Balun Designs #1115s or homebrew).
- Coax: 50-ohm RG-8X, length to reach shack (~$0.50/ft, e.g., Amazon).
- Insulators: 2–3 PVC or ceramic insulators (~$5, e.g., RadioWorks).
- Rope: 100 ft UV-resistant Dacron (~$20, e.g., DX Engineering).
- Weatherproof Box: Small enclosure for capacitor (~$5, e.g., Amazon).
- Standoffs: PVC or plastic to keep ladder line off metal (~$5, e.g., hardware store).
- Connectors: Solder lugs, wire nuts, or clamps for ladder line/balun (~$5).
- Tools: Soldering iron, wire cutters, tape measure, SWR analyzer (e.g., NanoVNA, ~$50, optional), UV-resistant tape, zip ties.
- Total Cost: ~$75–$90 (homebrew, prices approximate).
Step-by-Step Instructions
1. Prepare the Dipole:
- Cut 92 ft of 14 AWG wire for the dipole.
- Divide into two 46 ft legs (one side and other side).
- Attach each leg to a center insulator (PVC or ceramic) with solder or clamps, leaving terminals for ladder line connection.
- Attach an insulator to the end of each leg for rope attachment.
2. Prepare the Feedline:
- Cut 40 ft of 450-ohm ladder line (adjustable; range 38–42 ft).
- Strip and solder ladder line ends to center insulator terminals, connecting to dipole legs.
- Secure connections with UV-resistant tape or heat shrink.
3. Install the Antenna:
- Feedpoint: Mount the center insulator at the feedpoint (20–50 ft high, e.g., tower, mast, or tree, as high as practical).
- Leg 1: Extend one 46 ft leg toward a support (e.g., tree, pole, or stake) at 10–30 ft height.
- Configure as inverted-V (sloping to support) or flat-top (if supports are high).
- If space is limited (<46 ft), fold or bend the leg (e.g., L-shape or vertical drop) to fit.
- Leg 2: Extend the other 46 ft leg to another support, similar configuration.
- Tension: Use Dacron rope to secure insulators to supports, maintaining slight tension to avoid sagging.
- Space: Ensure total span (feedpoint to supports) fits available space; ~100–120 ft ideal but adjustable.
4. Route the Ladder Line:
- From the feedpoint, route the 40 ft ladder line downward, keeping it perpendicular to the dipole for ~10 ft to minimize coupling.
- Use PVC standoffs or zip ties to keep ladder line clear of metal structures (e.g., tower, mast).
- Guide ladder line to a convenient point near ground level for balun connection.
5. Install the Capacitor and Balun:
- Capacitor:
- Near the ladder line’s end (ground level), cut one leg of the ladder line.
- Insert the 500 pF, 1 kV ceramic capacitor in series with the cut leg (solder or use lugs).
- Secure the capacitor in a weatherproof box (seal with silicone for outdoor use).
- Balun:
- Connect the ladder line (post-capacitor) to the 1:1 balun’s balanced terminals (solder or clamps).
- Attach 50-ohm RG-8X coax to the balun’s unbalanced (SO-239) output.
- Secure balun to a stake or mount to protect from weather.
- Route coax to the shack, avoiding sharp bends or metal contact.
6. Connect to Transceiver:
- Run the RG-8X coax into the shack and connect to the transceiver’s antenna port (PL-259).
- Ensure proper grounding of the transceiver and shack to minimize RFI (use a ground rod if needed, ~$10).
7. Tune and Test:
- Initial Check:
- Power on the transceiver and select 80m (e.g., 3.75 MHz for CW/SSB).
- Use an SWR analyzer (e.g., NanoVNA, ~$50) or the radio’s SWR meter to measure 80m SWR (target ~2:1–3:1 with capacitor).
- Adjust 80m:
- If SWR >3:1, adjust ladder line length (±2 ft, e.g., 38–42 ft) by trimming or folding back.
- Alternatively, replace capacitor with 400–600 pF (e.g., 470 pF or 560 pF, ~$1) to fine-tune.
- Retest SWR after adjustments.
- Tune with Antenna Tuner:
- On 80m, activate the antenna tuner (ensure low power, ~5W).
- Repeat for 30m and 15m if SWR ~2:1–4:1 (tuner can match up to ~3:1–5:1).
- Other Bands:
- Test 40, 20, 17, 12, 10m; SWR should be <1.5:1 (no tuning needed).
- If SWR >1.5:1 on these bands, check ladder line length (~40 ft) or balun connections.
- Final SWR:
- 80m: ~2:1–3:1 (tunable by antenna tuner).
- 40, 20, 17, 12, 10m: <1.5:1.
- 30, 15m: ~2:1–4:1 (tunable).
8. Optimize and Secure:
- Ensure ladder line hangs freely, avoiding ground or metal contact.
- Seal all outdoor connections (capacitor box, balun, coax) with silicone or coax sealant (~$5).
- Check dipole tension after a few days to account for rope stretch.
- Log antenna tuner settings for each band for quick operation.
Performance Expectations
- 80m: Moderate efficiency (92 ft vs. 130 ft ideal); 500 pF capacitor reduces SWR to ~2:1–3:1, tunable by antenna tuner. Suitable for local and some DX contacts (~3–4 dBi gain).
- 40–10m: Excellent; SWR <1.5:1 on 40, 20, 17, 12, 10m (no tuner needed). 30, 15m tunable by antenna tuner.
- Patterns: Inverted-V (higher feedpoint, lower ends) provides near-omnidirectional 80m coverage; dipole-like on 40–20m; multi-lobed on 17–10m. Flat-top improves gain slightly.
- Power: Safe for 20W; capacitor and balun rated for 100W+ for reliability.
Troubleshooting
- High 80m SWR (>4:1):
- Verify capacitor value (500 pF) and connections.
- Adjust ladder line length or try 470/560 pF capacitor.
- Extend dipole to ~120–130 ft (e.g., 60–65 ft per leg, folding ends if needed), re-tuning ladder line.
- Poor 40–10m SWR: Check ladder line (~40 ft), balun integrity, or dipole length (46 ft per leg).
- RFI in Shack: Add ferrite chokes (mix 31, ~$5) on coax near transceiver; ensure proper grounding.
- Antenna Tuner Fails: If SWR >5:1, reduce power (2–5W) or adjust capacitor/ladder line.
Notes
- Why 80-10 Hybrid Dipole: Optimized for 80–10m with a 500 pF capacitor for improved 80m SWR (~2:1–3:1), fits in ~100–120 ft space (adjustable), leverages antenna tuner. Simpler/cheaper than a fan dipole (~130 ft, better 80m but no capacitor).
- Flexibility: Legs can be sloped (inverted-V) or straight (flat-top); fold ends to fit smaller spaces with minimal impact due to ladder line.
- Safety: Use insulated gloves when handling wires near supports; ensure capacitor box is sealed for outdoor use.
- Alternative: 80m loop offers better 80m efficiency but is slightly more complex.
80-Meter Full-Wave Loop Antenna
Instructions for 80-Meter Full-Wave Loop Antenna
Materials Needed
- Wire: 130 ft of 14–18 AWG stranded copper or copper-clad steel (~$13, e.g., Amazon, DX Engineering).
- Ladder Line: 40 ft of 450-ohm window line (~$20, e.g., DX Engineering, ~$0.50/ft).
- Capacitor: 500 pF, 1 kV ceramic capacitor (for 20W; ~$1–$2, e.g., Mouser, DigiKey, eBay).
- Balun: 1:1 current balun, 100W rating, mix 31 ferrite (~$20–$30, e.g., Balun Designs #1115s or homebrew).
- Coax: 50-ohm RG-8X, length to reach shack (~$0.50/ft, e.g., Amazon).
- Insulators: 4–5 PVC or ceramic insulators (~$10, e.g., RadioWorks; for feedpoint and corners).
- Rope: 100 ft UV-resistant Dacron (~$20, e.g., DX Engineering).
- Weatherproof Box: Small enclosure for capacitor (~$5, e.g., Amazon).
- Standoffs: PVC or plastic to keep ladder line off metal (~$5, e.g., hardware store).
- Connectors: Solder lugs, wire nuts, or clamps for ladder line/balun (~$5).
- Tools: Soldering iron, wire cutters, tape measure, SWR analyzer (e.g., NanoVNA, ~$50, optional), UV-resistant tape, zip ties.
- Total Cost: ~$75–$95 (homebrew, prices approximate).
Step-by-Step Instructions
1. Prepare the Loop:
- Cut 130 ft of 14 AWG wire for the 80m full-wave loop (perimeter for 3.5 MHz: ~1005/3.5 = 130 ft).
- Form a continuous loop, but leave open at feedpoint for connection.
- Plan a quadrilateral or triangular shape, with corners supported by trees, poles, or stakes:
- Feedpoint: 20–50 ft high (e.g., tower, mast, tree).
- Corners: 10–30 ft high, spaced to fit ~130 ft perimeter.
- Attach insulators at feedpoint and corners for rope support.
2. Prepare the Feedline:
- Cut 40 ft of 450-ohm ladder line (adjustable; range 38–42 ft).
- At feedpoint, attach a center insulator (PVC or ceramic) to break the loop wire.
- Solder or clamp ladder line ends to the loop’s open ends at the insulator.
- Secure connections with UV-resistant tape or heat shrink.
3. Install the Loop:
- Feedpoint: Mount the center insulator at the feedpoint (20–50 ft high, as high as practical).
- Loop Path:
- From feedpoint, extend wire to corner 1 (e.g., ~30–40 ft, sloping to 10–30 ft).
- From corner 1 to corner 2, extend ~30–40 ft (horizontal or sloped).
- From corner 2 to corner 3 (if quadrilateral), extend ~30–40 ft, or directly back to feedpoint (if triangular).
- Return to feedpoint to close the loop, adjusting lengths to total ~130 ft.
- If space is limited, fold or bend segments (e.g., L-shape or vertical drops) to fit.
- Tension: Use Dacron rope to secure insulators at corners to supports, maintaining loop shape and slight tension.
- Space: Fits in ~100–150 ft area; adjust shape (e.g., rectangle, triangle) to available space.
4. Route the Ladder Line:
- From feedpoint, route the 40 ft ladder line downward, keeping it perpendicular to the loop plane for ~10 ft to minimize coupling.
- Use PVC standoffs or zip ties to keep ladder line clear of metal structures.
- Guide ladder line to a point near ground level for balun connection.
5. Install the Capacitor and Balun:
- Capacitor:
- Near ladder line’s end (ground level), cut one leg of the ladder line.
- Insert the 500 pF, 1 kV ceramic capacitor in series with the cut leg (solder or use lugs).
- Secure capacitor in a weatherproof box (seal with silicone).
- Note: If 80m SWR is <2:1, capacitor may be optional or used for 30m/15m tuning.
- Balun:
- Connect ladder line (post-capacitor) to the 1:1 balun’s balanced terminals.
- Attach RG-8X coax to the balun’s unbalanced (SO-239) output.
- Secure balun to a stake or mount, protecting from weather.
- Route coax to the shack, avoiding sharp bends or metal contact.
6. Connect to Transceiver:
- Run RG-8X coax into the shack and connect to the transceiver’s antenna port (PL-259).
- Ground the transceiver and shack to minimize RFI (use a ground rod, ~$10).
7. Tune and Test:
- Initial Check:
- Power on the transceiver, select 80m (e.g., 3.75 MHz for CW/SSB).
- Use the radio’s SWR meter or NanoVNA (~$50) to measure 80m SWR (target ~1.5:1–2:1; loop is resonant).
- Adjust 80m:
- If SWR >2:1, adjust ladder line length (±2 ft, e.g., 38–42 ft) or loop perimeter (±2–5 ft, e.g., 128–134 ft).
- If needed, adjust capacitor (400–600 pF, e.g., 470 pF) to fine-tune 80m or other bands.
- Retest SWR.
- Tune with Antenna Tuner:
- On 80m, activate the antenna tuner if SWR >1.5:1 (use ~5W).
- Repeat for 40, 30, 20, 17, 15, 12, 10m if SWR ~2:1–5:1 (tuner matches up to ~3:1–5:1).
- Expected SWR:
- 80, 40, 20, 15, 10m: ~1.5:1–3:1 (often no tuner needed).
- 30, 17, 12m: ~3:1–5:1 (tunable by antenna tuner).
- Other Bands:
- Test all bands; loop is resonant on harmonics (3.5, 7, 14, 21, 28 MHz).
- If SWR >3:1 on non-harmonic bands, use antenna tuner.
8. Optimize and Secure:
- Ensure ladder line avoids ground/metal contact.
- Seal outdoor connections (capacitor box, balun, coax) with silicone or coax sealant (~$5).
- Check loop tension after a few days for rope stretch.
- Log antenna tuner settings for each band.
Performance Expectations
- 80m: Excellent efficiency; ~130 ft full-wave loop offers ~5–6 dBi gain, ~1–2 dB better than dipole. SWR ~1.5:1–2:1 (tunable by antenna tuner). High-angle radiation (NVIS) ideal for local/regional contacts; some DX capability.
- 40–10m: Good; resonant on 40, 20, 15, 10m (SWR ~1.5:1–3:1, often no tuner). 30, 17, 12m SWR ~3:1–5:1, tunable by antenna tuner. Patterns: directional on higher bands (broadside to loop).
- Patterns: Cloud-warmer on 80m (NVIS); multi-lobed on 40–10m, depending on shape and height.
- Power: Safe for 20W; capacitor and balun rated for 100W+.
Troubleshooting
- High 80m SWR (>3:1):
- Verify loop perimeter (~130 ft) and capacitor (500 pF).
- Adjust ladder line (±2 ft) or try 470/560 pF capacitor.
- Trim loop to 128–134 ft for resonance (1005/f MHz).
- High 40–10m SWR: Check ladder line (~40 ft), balun, or loop connections.
- RFI in Shack: Add ferrite chokes (mix 31, ~$5) on coax near transceiver; ensure grounding.
- Antenna Tuner Fails: If SWR >5:1, reduce power (2–5W) or adjust capacitor/ladder line/loop length.
Notes
- Why 80m Loop: Outperforms the 80-10 Hybrid Dipole by KB5WVK on 80m (higher gain, lower SWR), uses 500 pF capacitor (if needed), fits in ~100–150 ft area, leverages antenna tuner. More efficient than dipole but slightly more complex.
- Flexibility: Shape as rectangle, square, or triangle; adjust corners to fit space with minimal impact due to ladder line.
- Capacitor: Optional if 80m SWR is low; useful for fine-tuning 80m or other bands.
- Safety: Use insulated gloves near supports; seal capacitor box for outdoor use.
- Alternative: 80-10 Hybrid Dipole by KB5WVK is simpler but less efficient on 80m.