Aurora AU-520 / AU-520M Features

• 500W PEP HF / 200W 6m operation with ~80% nominal efficiency

• Integrated AC/DC power supply (80–264VAC, 47–63Hz, PF > 0.94)

• All amateur modes and bands (160m–6m)

• Integrated remote operation with:

  • Maestro™

  • iPad® / iPhone®

  • PC / Laptop

• Four independent band/mode receivers

• Full duplex cross-band operation

• True diversity reception

• Two receive-only ports

• Two transverter/exciter ports

• Integrated SO2R solution (OTRSP support) in a single radio

• Contest band filters with >50 dB rejection (band-to-band)

• Direct sampling SDR: 245.76 Msps, 16-bit

• 115 dB RMDR @ 2kHz spacing

• 155 dB dynamic range

• Built-in 500W automatic antenna tuner

• 10 MHz reference input

• Integrated GNSS receiver with antenna—maintains frequency accuracy without adjustment

• Optional high-performance GPSDO with 10 MHz output for external equipment

• 8-inch 1920 x 1200 IPS display (AU-520M) with external monitor port

FlexRadio AU-520 / AU-520M – Technical Specifications

Receiver

• Independent Band/Mode Receivers (Max): 4

• Reciprocal Mixing Dynamic Range (RMDR): 110 / 115 dB

• ADC Bits / Sampling Rate: 16-bit / 122.88 Msps

• Frequency Coverage: 30 kHz – 54 MHz

• Amateur Band Preselectors: 7th Order

• Digital Audio Channels (DAX / DAX IQ): 4 / 4

• Receive Only Ports (Base / Including XVTR Ports): 2 / 4

• Full Duplex RX/TX Operation:

Spectrum / Waterfall Display (AU-520M Only)

• Internal Touch Panel Display (Diagonal): 8-inch

• Integrated Display Resolution: 1920 x 1200

• Connection Port: HDMI®

• Max Spectrum / Waterfall Displays: 2 (on M model display)

• Spectrum / Waterfall Bandwidth (Min / Max): 5 kHz – 14 MHz

• Max Spectrum Dynamic Range (Zoomed): >145 dB

• Min Spectrum Resolution Bandwidth: 1.46 Hz/px (bin)

Transmitter

• Transmitter Output (160m–10m): 1–500W (125W AM)

• Transmitter Output (6m): 1–200W (50W AM)

• Harmonic Suppression: ≤ 60 dBc

• Transverter Ports: 2

• Transverter IF Frequency / Power: 100 kHz–54 MHz, adjustable up to +10 dBm

• Integrated ATU Range: 3:1 SWR

• SmartSignal™ Adaptive Pre-distortion:

General

• Modes: SSB, CW, AM, SAM, FM, RTTY, Digital

• Integrated Remote Operation (SmartLink™):

• Client Options: Maestro™, PC, Mac, iPhone®, iPad®

• Integrated GNSS Receiver: 12-channel, <35s TTFF (cold start)

• Supported GNSS Systems: GPS, Galileo, GLONASS, QZSS, SBAS

• Frequency Stability (0°C–50°C):

  • GNSS: ±0.001 ppm

  • TCXO: ±0.5 ppm

• Optional GPSDO: 10 MHz output, 5 x 10⁻¹³ stability over 24 hours

• External 10 MHz Reference Input:

• Power Requirements:

  • Receive: 35W

  • Transmit: 675W

  • Input Voltage: 80–264 VAC

• Dimensions (H x W x D):

  • 6.74" x 14" x 13.25" (17.1 cm x 35.6 cm x 33.7 cm)

Note: Features subject to change without notice. Some features may be introduced in future software updates.

Aurora FAQ

What is Aurora?
FlexRadio has developed a new HF transceiver with a 500W output on 160–10m HF bands (200W on 6m). This radio replaces traditional linear amplification with Polar Modulation (PM), integrating a 500W transmitter, automatic tuner (ATU), and power supply into a compact unit. This means less cabling, simpler setup, and improved efficiency for both home and portable stations. Aurora represents the most significant advancement in amateur radio transmitter technology in the last 50 years.

Introduction to Polar Modulation
Polar Modulation separates an RF signal into amplitude and phase components. Each is amplified independently using highly efficient switch-mode amplifiers (Class D, E, or F). Originally developed in the 1950s and revived with modern DSP, this technique allows for cleaner, smaller, and more efficient transmitters than legacy designs.

Why is the Aurora transmitter so efficient?
It uses Class D switch-mode amplifiers and DSP to handle amplitude and phase separately—dramatically reducing energy lost as heat.

Why is the Aurora radio so small for 500W?
Its efficiency allows for a smaller heat sink and compact integration of the transmitter and power supply in a space similar to a 100W rig.

I see the radio weighs only 18 pounds (8kg). This doesn’t include the 500W transmitter and power supply, right?
It actually does include all of that. The Aurora is a complete system in a compact form.

I understand Aurora is around 80% efficient.
Compared to a 40% efficient rig, Aurora generates just 17% of the heat, allowing for a 500W transmitter in a 100W-sized enclosure.

Is this radio compatible with digital modes like FT8 and RTTY?
Yes. It’s rated for 25–50% ICAS duty-cycle. Always monitor temperatures.

What is the maximum power on FT8, RTTY, etc.?
Tested at 100% transmission for 2 hours—though not recommended, it proves its robustness.

When can I add an Aurora amplifier to my Brand X radio?
You can't. The system requires polar modulation inputs, only available through FlexRadio’s integration.

Can I integrate this radio into a remote station setup?
Yes. It’s built on the same SmartLink-capable remote platform as the FLEX-8000 series.

Will I need an external tuner?
No. It includes an internal tuner rated for up to 3:1 SWR. External tuners may be used but must handle 500W.

How efficient is Aurora vs. legacy amplifiers?
Aurora achieves 80% efficiency. Legacy amps operate around 40–60%.

What does 80% efficiency mean in practice?
80W of RF output per 100W input. Only 20W lost as heat.

What’s the difference between the AU-510 and AU-520?

• AU-510: 1 SCU, 4 antenna ports (2 @ 500W), 2 receivers on one antenna.

• AU-520: 2 SCUs, 6 antenna ports (2 @ 500W), 4 receivers on 2 antennas.

I already have a radio. Why get Aurora?
You get integrated 500W output, better energy efficiency, reduced heat, lower power costs, and simplified setup.

Is 500W overkill for POTA or portable ops?
Legacy setups need 1,250–1,500W input and weigh ~47lbs. Aurora uses 650–700W input and weighs just 18lbs.

What about DXpeditions?
Aurora is lightweight, uses less power/fuel, and fits in a carry-on—ideal for DXpeditions.

Do I need extra cooling or fans?
No large setup needed. Active cooling is included and quieter than expected.

Will this reduce shack heat?
Yes. Lower heat output means a cooler environment.

Does efficiency mean better reliability?
Yes. Less thermal stress equals longer life and stable operation.

Can I transmit outside the amateur bands (MARS, SHARES)?
No. Hardware is limited to HF/6m amateur bands.

What power supply is required?
80–264VAC input. Full power available even at 120VAC.

Can I run it at 13.8V DC?
No. Only AC input is supported.

What is max power on 6m?
200W.

Is the ATU included?
Yes, rated to 3:1 SWR.

Can I use an external ATU?
Yes, if rated for 500W or more.

Can I connect an external amplifier?
Yes—but avoid overdriving. Warranty may be voided by misuse.

Does it support SmartLink, multiFLEX, etc.?
Yes. Features match those of the FLEX-8000 series.

Does it support transverters?
Yes, via XVTR ports like FLEX-6000 and 8000 series.

Aurora Series Comparison