Tag Archives: 70 MHz

Working aurora propagation on the amateur radio bands — especially 50 MHz (6m), 70 MHz (4m), and 144 MHz (2m) — is a thrilling and distinctive experience. Aurora propagation is caused by charged particles from the Sun (usually during a geomagnetic storm) interacting with Earth’s magnetic field, energizing the auroral zone and creating a reflective “curtain” that VHF signals can bounce off.

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Basics of Aurora Propagation

• Occurs at high latitudes, primarily over northern Europe, Canada, and the northern U.S.
• Reflected signals are scattered (Doppler effect), leading to:
  • Distorted audio — speech sounds harsh or “buzzy”
  • CW and tones are raspy, often called “auroral tone”
• Reflections are strongest from the northern direction (for Northern Hemisphere operators)
• Most effective during or just after geomagnetic storms (Kp index ≥ 5)

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When to Watch for Aurora

• Solar cycle activity peaks increase chances
• Watch for:
  • Solar flares (M or X class)
  • Coronal Mass Ejections (CMEs) reported by NOAA or spaceweather.com
• Aurora can appear anytime day or night, but late afternoon into evening is often best in Europe

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Bands and Techniques

50 MHz (6 metres)

• Best band for aurora work: long wavelengths reflect better off the curtain
• SSB and CW both work
• Beam antenna northward — the reflection often comes from the auroral arc to the north
• Use high power and narrow bandwidth
• Signals are typically weak and fluttery
• Range: ~800–2000 km

70 MHz (4 metres)

• Less commonly used, but similar behaviour to 50 MHz
• Aurora QSOs possible with CW and SSB
• Fewer active stations, but a unique opportunity if you’re licensed for 4m

144 MHz (2 metres)

• Much more angle-dependent — must beam exactly at the auroral curtain
• Signals much more distorted; CW heavily preferred
• Beams must be well aligned — aurora scatter is very directional
• Aurora “backscatter” can allow contacts in odd directions
• Best success with CW, high ERP, narrow filtering

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⚙️ Operating Tips

1. Use CW or SSB
   • CW is best: tones become a “buzz”, but still readable
   • SSB becomes “growly”, harder to copy but still usable
2. Point antennas north
   • Slight adjustments can help tune into the auroral arc
3. Call CQ AURORA
   • Examples: “CQ AUR DE G4MCU or just CQA DE G4MCU”
4. Listen for others on known calling frequencies:
   • 50.100–50.120 MHz CW/SSB (Europe)
   • 70.200 MHz (CW/SSB)
   • 144.050–144.100 MHz CW
   • 144.300 MHz (SSB calling)
5. Use narrow filters to reduce flutter and fading
6. Watch cluster spots and aurora alerts: DX maps, DX cluster, LiveMUF, or aurora watch apps

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Example Contact Strategy for JO01 (UK)

• Beam North or North-East
• On 6m, call CQ on 50.110 CW, then check 50.120–130 SSB
• On 2m, call CQ on 144.050 CW, then 144.300 SSB
• Listen for DL, SM, LA, OH, OZ — common aurora QSO partners
• During good auroral activity, contacts up to 2000 km possible

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Helpful Tools

• Aurora Alerts: aurorawatch.lancs.ac.uk
• Kp Index Monitor: NOAA SWPC
• Real-time spots: DX Maps VHF
• Spaceweather news: spaceweather.com

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Here’s a full Aurora Radio Equipment and operating checklist tailored for working 50, 70, and 144 MHz from JO01 (southeast UK where G4MCU is located) or nearby areas

Equipment Essentials

Equipment	Recommendations
Transceiver	All-mode VHF set (e.g., Icom IC-7100, FT-847, IC-9700)
Modes	CW preferred, SSB possible
Power	50–100W or more is ideal
Antenna	Yagi with rotator; minimum 3–5 elements on 2m
Preamp	Masthead LNA especially useful on 2m
Logging	Digital or paper; record time, station, frequency, mode, direction
Filters	Narrow IF filter (CW ~300 Hz) helpful in auroral flutter conditions
Computer Clock	Accurate sync (especially for digital modes like FSK441, if used)

Aurora VHF Operating Checklist (50, 70, 144 MHz)

Equipment Essentials

– Transceiver: All-mode VHF (e.g., Icom IC-7100, FT-847, IC-9700)

– Modes: CW preferred, SSB possible

– Power: 50-100W or more is ideal

– Antennas: Directional Yagi (3-5 elements min. on 2m)

– Preamp: Masthead LNA improves weak signals

– Filters: Narrow IF filter (CW ~300 Hz)

– Accurate computer clock for any digital use (FSK441, MSK144)

Frequencies to Monitor (Europe)

50 MHz:

– CW: 50.090-50.120 MHz

– SSB: 50.130-50.200 MHz

70 MHz:

• CW/SSB: 70.200 MHz (low activity; be active!)

144 MHz:

• – CW: 144.050-144.100 MHz
• – SSB: 144.300 MHz

Operating tips

• – Beam North/North-East; rotate slowly
• – Use CW for better readability in flutter
• – Space CW characters out; slow speeds preferred
• – Record QSOs for later review
• – Avoid fast CW/digital unless experienced
• Aurora Alert System
• Web Tools:
• – AuroraWatch UK: aurorawatch.lancs.ac.uk
• – SolarHam: solarham.net
• – NOAA SWPC: swpc.noaa.gov
• – DX Maps: dxmaps.com (select VHF/EU)
• – LiveMUF: livemuf.com
• – Twitter: @aurorawatchuk, @TamithaSkovWeb Tools:
• – AuroraWatch UK: aurorawatch.lancs.ac.uk
• – SolarHam: solarham.net
• – NOAA SWPC: swpc.noaa.gov
• – DX Maps: dxmaps.com (select VHF/EU)
• – LiveMUF: livemuf.com
• – Twitter: @aurorawatchuk, @TamithaSkov
• – Mobile apps: Aurora Alerts, My Aurora Forecast, HamAlert

When to Operate

– Kp Index 5+: aurora possible; 6-8 very likely

– After CME or geomagnetic storm alert (G1-G3)

– M or X class solar flares with CME potential

– Best in afternoon/evening but can occur anytime

Sample Operating Schedule

16:00-18:00: 50 MHz CW calling and monitoring

18:00-19:30: 144 MHz CW/SSB, beam north

19:30-20:30: Try 70.200 MHz CW/SSB

20:30-22:00: Return to 6m/2m as aurora builds

Overnight: Check 6m occasionally if storm strong