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Icom America - 2 way radios

IC-7851

HF/50MHz Transceiver

HF/50MHz Transceiver - The Pinnacle of HF Perfection

Premium components yield premium performance

 

Dual AGC loops

The IC-7851 has multiple AGC loops. The AGC voltages detected in front of and behind the digital IF filter in the DSP unit. The first AGC loop prevents saturation of the 1st IF amplifier. The other AGC loop detects the AGC voltage at the digital IF filter output which has only passed the intended signal and draws the full potential from the digital IF filter. Combining the digital IF filter, manual notch, and the 1st IF stage, these are all controlled by the DSP unit. 110dB of ultra wide dynamic range in the receiver means the IF amplifier is distortion free from strong signals.

Dual AGC Loops

Image rejection mixer

Simple receiver system configuration is the best way to eliminate sources of the spurious signals and distortion from transceivers.

The IC-7851 uses a double conversion system composed of a D-MOS FET 1st mixer and image rejection mixer for the 2nd stage. The 1st mixer stage is driven with a signal from the highdrive Local Oscillator with excellent C/N.

The image rejection mixer for the 2nd stage reduces signal distortion through IF processing and provides a high-fidelity signal to the DSP unit. This system provides wide dynamic range, reducing the distortion from strong signals and lower intermodulation.

High performance OCXO unit

The IC-7851 uses the OCXO (Oven Control Crystal Oscillator) unit which is stable to within ±0.05ppm at 0°C to 50°C. This specification means that even on the 50MHz band, frequency error is less than 2.5Hz! In addition, a 10MHz reference frequency can be input and output for accurate tuning.

OXCO unit

200W Output power at full duty cycle

The push-pull power amplifiers using power MOS-FETs work on 48V DC. They provide a powerful 200W output power at full duty cycle and low transmit intermodulation. An effective cooling system maintains internal temperatures within a safe range and prevents thermal runaway.

PA unit and heat sink

Solid aluminum main dial knob

The main dial tuning knob is pure functional beauty. Machined from a solid aluminum block, the main dial tuning knob gives you a solid operational feel. The diamond engraved accents are cosmetic perfection – expected only from a radio of this caliber.

Main dial knob

  

  

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