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Solid Design Basics and HF Expertise
Raising the Bar

Contesters and DXers are always looking for that competitive edge to magically pull out the 

weak signal that is either the rare country or multiplier they need to climb up the list. Larger 

antennas, higher gain pre-amps and other devices in line are great. However, what happens 

inside the radio with all those signals coming down your feedline can defeat all your efforts. 

With the design of the IC-7851, Icom’s engineers focused on a new Local Oscillator (LO) 

that drastically reduces the phase noise. As a result of this design, the purity of the LO achieves 

a Reciprocal Mixing Dynamic Range (RMDR) of 110dB.    

In addition to the incredibly clean LO allowing you to hear the weak signals, the new spec-

trum scope design enables you to see the weak ones! Faster processors, higher input gain, 

higher display resolution and a cleaner signal from the receiver’s LO will give you a new 

window into the RF world. Adding this performance and functionality for both receivers give 

you a dual scope portal.

THE 

TRANSCEIVER

1

Summary of Contents for IC-7851

Page 1: ...THE TRANSCEIVER...

Page 2: ...the design of the IC 7851 Icom s engineers focused on a new Local Oscillator LO that drastically reduces the phase noise As a result of this design the purity of the LO achieves a Reciprocal Mixing D...

Page 3: ...ssive 20dB improvement is seen with the IC 7851 s 10 kHz measure ment and more than 30dB improvement at a 1 kHz measurement in com parison to the IC 7800 Phase Noise Characteristics Comparisons Receiv...

Page 4: ...r 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 wel...

Page 5: ...851 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 dete...

Page 6: ...eble The receive audio can be tailored with mode specific Bass Treble or audio passband settings Digital Twin PBT Passband Tuning Once the IF filters have been tweaked the op erator has additional con...

Page 7: ...synthesizer announces the operat ing frequency mode and S meter level Programmed scan memory scan select memory scan VSC scan and f scan Auto tuning step function Dial lock function Main dial tension...

Page 8: ...V 2 V 0 5 V 28 29 9MHz 50 54MHz 0 13 V 1 V 0 32 V SM 50 DESKTOP MICROPHONE IC PW1 IC PW1EURO HF 50MHz 1kW LINEAR AMPLIFIER SP 34 EXTERNAL SPEAKER Automatic antenna tuner and compact detach able contr...

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