| IC-7851 HF Transceiver |
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 spectrum scope design enables you to see the weak
ones! Faster processeors 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.
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
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.
1.2 kHz Optimum
Roofing Filter
Despite the trend to switch to a down conversion or a
hybrid conversion receive design, Icom bel ieves in the sol id per formance of
the up-conversion design. In an up-conversion receiver, suppression of image
interference and reduce distortion from electric components is easily overcome.
A flat consistent performance is delivered over a wider frequency range.
The IC-7851 introduces a new 1.2kHz Optimum Roofing
Filter, greatly improving the in-band adjacent signal performance. This newly
developed filter overcomes the gap of a narrower roofing filter in an
up-conversion receiver.
Optimum Roofing Filter
Optimum Roofing Filter Characteristic Diagram
Crystal Clear LO (Local
Oscillator Design
Breaking the boundaries of traditional designs, the
IC-7851 employs a Direct Digital Synthesizer (DDS) along with a Phase Locked
Oscillator for the LO. The C/N ratio excels beyond the IC-7800 and other similar
class HF transceivers. This design significantly reduces noise components in
both receive and transmit signals.
LO C/N Characteristics Comparisons
Receiving Frequency: 14.2 MHz Mode: CW 1st LO
frequency: 78.655 MHz
SPAN = 20 kHz, RBW = 30 Hz, VBW = 10 Hz
IC-7851
IC-7800
Improved Phase Noise Characteristics
Phase noise is coherent in radio circuit design and the
new LO design introduced
in the IC-7851 makes some major breakthroughs while
utilizing the 64MHz, up-conversion receiver design introduced in the IC-7800.
An impressive 20dB improvement is seen with the IC-7851’s
10 kHz measurement
and more than 30dB improvement at a 1 kHz measurement in
comparison to the IC-7800.
Phase Noise Characteristics Comparisons
Receiving Frequency: 14.2 MHz Mode: CW 1st LO frequency: 78.655 MHz
IC-7851
IC-7800
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
2250 MFLOPS
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
Mini spectrum scope and audio scope
Mini dual spectrum scope and audio scope
Specifications for the audio scope
Specifications for the oscilloscope
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>
Premium components
yield premium performance
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.
Dynamic Range Characteristics
Dynamic Range (typical)
BPF Switching:
Mechanical Relays
The IC-7851 incorporates high-grade, long-term reliable
mechanical relays rather than PIN diodes for switching the Band Pass Filters
(BPF). This deployment of relays removes secondary distortion products from the
primary stage of signal processing.
BPF unit
Four 1st IF “Roofing”
Filters
Three high-spec 1st IF “Roofing” filters plus the new
1.2kHz Optimum Roofing Filter allow only signals within the filter passband to
the 1st IF amplifier stage. You can select the filter width from 15kHz, 6kHz,
3kHz and 1.2kHz, depending on your operating mode.
(FM mode is fixed at 15kHz)
1.2kHz Optimum Roofing Filter
3, 6, 15kHz High-Spec 1st IF filters
Digi-Sel Preselector
The preselector works between 1.5MHz and 30MHz and rejects
distortion componentsderived from out of band interference such as multi-multi
operation or strong broadcast stations. It automatically tracks the intended
signal keeping the preselector’s bandwidth centered on the operating frequency.
The center frequency of the preselector is manually adjustable from the DIGI-SEL
tuning knob on the front panel.
Automatic Preselector
Automatic Preselector bandwidth characteristics
Triple DSP Power
Three separate 24-bit AD/DA converters and dedicated DSP
processors are at the heart of the IC-7851. With one AD/DA and DSP dedicated to
the spectrum scope and two 24-bit AD/DA and DSP chips for the receivers and
transmit circuits, there is plenty of DSP power for the most demanding RF
environment.
Transmit/Receiver DSP (left) and Receiver DSP (right)
ADSP-21489 by Analog Devices
32-bit floating point DSP
2400 MFLOPS
393 MHz clock speed
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.
OCXO unit
200W Output Powerat
Full Duty Cucle
The push-pull power a m p l i f i e rs u s i n g 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.
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.
RTTY/PSK31 and PSK63
RTTY, PSK31 as well as the new PSK63 modes are available
at your finger tips without the use of a computer. The built-in
Modulator/Demodulators are activated by via the radio’s functions buttons or an
optional USB keyboard. TX memories make contacts a snap and communications logs
can be stored on an SD memory card.
RTTY mode display
Digital IF Filters
“Build your own” IF filters by adjusting the IF filter
width, 50-3600 Hz, as well as soft or sharp filter characteristics for your
perfect sound. Save these settings in three userdefined filter presets,
Wide/Mid/Narrow, by mode to give you full customization of your filters.
Filter preset screen
Digital Manual Notch
HF operators marvel at how well DSP reduces interfering
signals and noise. Signals such as heterodynes and AM Carriers can be eliminated
with automatic notch filter technology.
Making interference from RF sources such as beat signals
and RTTY signals is a thing
of the past. Additionally, the filter shape of the manual
notch can be adjusted in three steps – with more than 70dB of attenuation!
Manual Notch Filter Characteristics
Digital Twin PBT
(Passband Tuning)
Once the IF filters have been “tweaked,” the operator has
additional control with the digital twin passband tuning (PBT). The digital twin
PBT allows flexibility of both the IF shift and narrowing of the digital IF
passband by moving the IF passband. With the digital IF filters, PBT performance
allows you to cut away all the interference and noise to hear the actual signal.
Variable Level Noise
Reduction
The digital noise reduction separates a target signal from
noise components and noise suppression level is variable in 16 -steps, depending
on the noise level. The low latency digital noise reduction is achieved by
applying an adaptive filter using the high speed DSP computing power.
New Auto Digital
Noise Blanker
While most noise blanker reduces pulse type noise, the
IC-7851 introduces a new automatic digital noise blanker circuit. While using
the 15/9/6kHz roofing filters, the digital noise blanker gives you full control.
When the 1.2kHz Optimum Roofing Filter is activated, the best blanking level is
automatically selected. Additional adjustments allow you to tweak the threshold
level, blank time and attenuation level parameters.
Digital Transmit
Bandwith (TBW) and Audio Equalizer
With the flexibility of DSP-based waveform shaping,
transmit and receive audio quality is adjustable to suit your preference. Three
user-adjustable transmit filters, Wide/Mid/Narrow, allow you to set both the low
and high cut-off frequency limits. (100, 200, 300, 500Hz for lower and 2500,
2700, 2800, 2900Hz for higher frequencies.) In addition to the TBW filter, the
IC-7851 has an equalizer to digitally tweaks your transmit audio with separate
bass and treble controls (11 steps each for bass and treble). The receive audio
can be tailored with modespecific Bass/Treble or audio passband settings.
Digital RF Speech
Compressor
The DSP controlled RF speech compressor provides
additional punch while maintaining the original tone quality of the operator.
The IC-7851 utilizes the 32-bit DSP for the RF speech compressor, providing the
maximum punch without the fuzzy sound. It’s great for breaking through the noise
and hash to complete the QSO.
SD Memory Card Slot
Save operator profiles, digital voice keyer, CW memory
keyer, RTTY/PSK logs, IC-7851 “Screen Shots” and various other operational
settings to your SD Memory card.
SD Memory Card Slot
Digital Voice
recorder
The digital voice recorder captures both receive and
transmit audio to your SD or USB storage devices. Up to 9 hours of continuous
audio recording is possible with 2 GB of storage. Record your QSO with a rare
entity or record your operating time in a contest. Operating frequency, mode,
S-meter and output power are automatically captured.
Recorded list display
Memory Keyer
Whether operating phone, CW, RTTY or PSK31/63, the IC-7851
has a convenient
memory keyer to ease operations. Record your CQ, station
information or other items in one of 8 keyer memories for the CW and digital
modes; 4 memories for phone operation. For CW, the memory keyer has timesaving
functions like auto repeat, contest serial number counter and short Morse number
functions. For phone operation, you have a voice-saving auto repeat function.
Improved Automatic
Antenna Tuner
The automatic antenna tuner utilizes tunesetting memories
to record the best tuner configuration for the lowest SWR. This allows a faster
response time when jumping bands or moving around in the same band.
Internal Antenna
Switch
With six antenna ports – two receive-only and four
receive/transmit – the IC-7851 enables the operator to have fingertip control
over a vast array of antenna configurations. Switch to 80/160m and you want to
use your beverage
antenna for receive, but transmit on your vertical. Not a
problem: the antenna switch
memory will automatically switch antennas when you select
the band you want to operate.
This is very convenient when using the RS-BA1 for remote
base operation.
Enhanced PC
Connectivity
The IC-7851 has various computer interfaces, giving you
maximum connectivity between your computer and radio. Digital modes become a
snap when controlling with the USB port. USB audio and some CI-V commands
including USB send (DTR/RTS) and USB keying (CW and RTTY) are selectable. You
can also interface your computer with the S/P DIF optical digital interface
provides audio I/O.
The Ethernet jack allows you to connect the IC-7851
directly to your router and control your radio over your wireless Internet, or
travel the globe and operate your station remotely over the Internet.
Firmware Update
Capability
The IC-7851 can grow as feature and function enhancements
become available via the USB or your SD Card.
Simplified Remote
Control (Optional RS-BA1)
Remote base operation is made easy as the IC-7851
operating system incorporates
the remote base server software. A computer is not
required in the shack for audio or rig control. Up to three, unique user
log-in/password configurations are part of the internal server. As the rig
control has a priority of service, the controls will feel like you are right in
front of your rig.
Optional RS-BA1 main features
Antenna
Transmitter
CW
Operation
scan
| Order No. | ||
|---|---|---|
| IC-7851 | Bel of Mail |
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Tussentijdse prijswijzigingen en typefouten voorbehouden.
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