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Icom America - 2 way radios


HF/50MHz Transceiver

HF/50MHz Transceiver - The Pinnacle of HF Perfection

Twice the speed, sensitivity, resolution and more control


Improved spectrum scope

Following the design linage of the IC-7800, the IC-7851 uses a dedicated DSP unit for the Fast Fourier Transform (FFT) spectrum. The 2250 MFLOPS DSP processor enables a new dual scope function and significantly faster sweep speeds and better accuracy than in the IC-7800.

Scope DSP
TMS320C6745 by Texas Instruments
32-bit floating point
370 MHz clock speed

Scope comparison

*1 Number of dots shown at the 60 dB level, when receiving a signal.
*2 SPAN = More than 20 kHz, SPEED = Slow
*3 SPAN = Less than 20 kHz, SPEED = Fast
*4 SPAN = 500 kHz, SPEED = Slow

Audio scope function

The audio scope simultaneously shows an oscilloscope and FFT for receive and transmit audio. Adjust your transmit audio by watching your compressor level, equalization and mic gain settings to give you the audio you want for SSB. The oscilloscope shows the CW waveform. On receive, you can see the power of your filtering by watching filtering adjustments take out interfering signals including filter width and notch filter placement. The processing power in the IC-7851 allows for dual mini band scopes as well as the audio scope.

Mini spectrum scope and audio scope

Mini dual spectrum scope and audio scope

Specifications for the audio scope

  • Attenuator: 0 dB, –10 dB, –20 dB and –30 dB
  • FFT scope with waterfall and FFT scope without waterfall
  • Waveform color and drawing (outline or fill) settings for the FFT scope

Specifications for the oscilloscope

  • Level: 0dB, –10 dB, –20 dB and –30 dB
  • Sample rate: 1ms/Div, 3ms/Div, 10ms/Div, 30ms/Div 100ms/Div and 300ms/Div, 5 Div width
  • Waveform color setting

Dual scope function

While you can watch both receivers on the scope of the IC-7800, within the limits of the scope bandwidth, the IC-7851 introduces the new dual scope – the ability of watching both receivers in separate spectrum scopes. The dual scope function is vital for watching for multipliers or band openings in contests, or working all bands/modes on a DXpedition.

Dual scope example (Vertically aligned)

Dual scope example (Horizontally aligned)

High resolution waterfall display

The waterfall display captures signal strengths over time. This allows you to see signals that may not be apparent on a normal scope. Additionally, the combination of the scope attenuator and the wide screen mode gives you a better view of weaker signals as band conditions change. For the ultimate scope enhancement, the IC-7851 has a digital video interface (DVI-I) for a larger display.

Spectrum scope with waterfall
(wide screen setting)

Click control

By connecting a human interface device (such as a USB mouse, trackball or touchpad) to the USB port on the rear panel, you gain control over the spectrum display pointer for “Click-and-Listen” receiver control. Fix/Center mode, sweep speed and other settings are controllable.

For example
  • Left click to change operating frequency
  • Click a button (either left or right) and move right or left side on the screen to increase or decrease the operating frequency (similar to rotating the main dial)
  • Right click to temporarily change the receive frequency. Release the mouse button to return.



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