IC-7851 HF/50MHz Transceiver

HF/50MHz Transceiver - The pinnacle of HF perfection 

Competitive advantage: reciprocal mixing dynamic range
RMDR: 110dB raising the bar
Design advances developed by the Icom HF engineers for the Local Oscillator (LO) enable the IC-7851 to set a new benchmark for amateur radio receivers. The goal was to dramatically reduce the phase noise that degrades the target signal due to the sum of the entire signal present. The result was a RMDR of 110dB*. Below is a comparison of the improvement over the IC-7800. (*At a 1kHz offset frequency; Receiving frequency: 14.2 MHz Mode: CW, IF BW: 500 Hz; Roofing Filter IC-7800 = 3 kHz, IC-7851 = 1.2 kHz) 

RMDR Comparison

RMDR (Reciprocal Mixing Dynamic Range) is the relative level of an undesired signal, offset "n" kHz from the RX passband, which will raise noise floor by 3 dB. The local oscillator phase noise will mix with strong unwanted signals and unavoidably generate noise which masks a wanted signal. 

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. 

+40dBm IP3 (3rd Order Intercept Point)
The IC-7851 continues the +40dBm, 3rd order intercept point and 110dB receiver dynamic range benchmark set by the IC-7800. To achieve this superb receiver performance, the entire analog circuitry and components have been re-engineered to match the DSP units. A newly designed LO amplifier generates high output while keeping flat frequency characteristics over a 60MHz wide range. 

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 receivers
The IC-7851 incorporates two completely independent receivers, from the antenna inputs all the way through to the stereo headphone and individual external speaker outputs. All the performance of the first receiver is duplicated for a perfectly matched set of "Twins". When connected to external stereo headphone, main and sub receiver audio can be mixed or separated to the right and left. 

Dimensions
425×149×435 mm
16.73×5.87×17.13 in

Weight
23.5 kg; 51.8 lb 

Temperature range
0°C to +50°C; +32°F to +122°F 

• Rack mount handles
• SD card
• AC power cable
• Spare fuses
• Plugs