IC-7700 Review (long version)
George Thomas, W5JDX, of AmateurLogic.tv and Ham Nation discusses the IC-7700 in this in depth review with Icom America's Ray Novak, N9JA.
Read the QST Review of the IC-7700 here!
*Click the image to view the PDF review.
110dB dynamic range and
+40dBm 3rd order Intercept Point (IP3)
The IP3 performance of a radio can be improved by sacrificing sensitivity, but Icom
considers this a poor choice. To achieve REAL high-performance, Icom reviewed all
of the analog receiver circuitry. The IC-7700 employs mechanical relay BPF switching,
a digitally tuned pre-selector, and three Hi-spec 1st IF filters (roofing filter)
in a Dynamic range characteristics (in 14MHz band) clean and simple double-conversion
superheterodyne design. By balancing the analog and DSP functions, the IC-7700 provides
superior sensitivity simultaneously with a superb dynamic range of 110dB, and +40
dBm IP3 (even in USB mode with 2.4 kHz filter bandwidth)..
Better than +110dBm 2nd order intercept point (IP2)
An IP2 point of more
than +110 dBm* means the 2nd order distortion
from strong broadcast stations will be completely eliminated. The endless pursuit
of leading analog circuit engineering makes it possible to achieve this leading
edge level of performance.
* Measurements were made using custom equipment, due to the
limits of normal signal generators (SG) and duplexers to +85 dBm. The IP2 figure
is a typical value.
Double conversion superheterodyne system
While multiple IF stages can become a source of distortion products and spurious
responses, the IC-7700 utilizes Icom’s original image-rejection mixers in a simple
double conversion superheterodyne. This reduces distortion and produces a much cleaner
audio signal compared to triple or quadruple superheterodyne receivers.
High specification inband IMD
In-band IMD (Intermodulation Distortion) creates undesired spurious signals as a
consequence of non-linear processing of multiple signals. All (2nd, 3rd or even
higher) orders of IMD performance are superior in the IC-7700. The improvement will
be especially evident in CW mode. You’ll notice the difference as you copy weak
signals without internal distortion or noise.
Inband IMD characteristics
Band pass filter
While some may lead you to believe that coils
and capacitors are all created equal, at Icom we know design excellence. Rather
than using switching diodes that can introduce distortion, the IC-7700 design utilizes
high-grade mechanical relays along with large capacitors and toroidal coils; resistant
to magnetic saturation, providing superior linearity, and greatly reducing distortion.
DIGI-SEL (Digital pre-selector)
The
DIGI-SEL (digital pre-selector) is a very narrow, user adjustable, pass band filter
designed to automatically track the operating frequency, attenuating interference
from out-of-band signals. While the pre-selector’s pass-band remains centered on
the operating frequency, on the fly adjustments are possible via front panel controls.
The DIGI-SEL is especially useful for multi-transmitter operation and near strong
broadcast stations by reducing the 2nd, 3rd, and even higher order IMD components
from other stations.
Pre-amplifiers
The IC-7700 has a total of 4 pre-amplifiers, two for the HF bands and two for the
50MHz band. The purpose of pre-amplifiers is to improve receiver sensitivity for
the pursuit of higher gain and a better noise figure. The IC-7700 employs a noiseless
feedback design with push-pull amplifiers. Using feedback transformers, the pre-amplifiers
provide a high IP3 while keeping a low noise figure.
1st mixer
The 1st mixer stage is driven with a signal from the high-drive Local Oscillator
with excellent C/N. A 16V p-p of high-level LO signal is applied to the mixer to
improve intermodulation characteristics while avoiding a parasitic oscillation or
noise.
Three Hi-Spec 1st IF filters (Roofing Filter)*1
The IC-7700 employs three Hi-Spec 1st IF filters (roofing filters) of 15kHz, 6kHz
and 3kHz before the 1st IF amplifier. Icom ordered special customized high specification
devices to improve IMD and achieve better impedance characteristics. As a result,
the 3kHz 1st IF filter provides approximately 134dB*2
of blocking dynamic range and allows you to pull out a weak signal in the presence
of strong adjacent signals.
*1 Icom calls the roofing filters “Hi-spec 1st IF
filters”, because their performance is much better than regular IF filters.
*2 At 14.1MHz receive, with 5kHz separation of interference signal.
2nd-stage image rejection mixer
The 2nd-stage image rejection mixer processes signals to reject spurious image responses.
In conjunction with the Hi-spec 1st IF filters (roofing filters), image rejection
of greater than 100dB is realized. The analog image rejection mixer’s linearity
makes it possible to use a simplified receiver design. This improves the distortion
performance of the receiver.
50MHz band preamplifier and mixer
The IC-7700 was designed with the 6m aficionado in mind. Rather than sharing circuits
used for HF, a separate preamplifier and mixer was designed especially for 6m. This
greatly improves the receiver sensitivity by reducing intermodulation characteristics,
enabling weak signal works without distortion or interference from strong signals
in the band.
Two AGC Loops
The IC-7700 has two AGC loops. The AGC voltages detected in front of and behind
the digital IF filter in the DSP unit. The first AGC loop prevents the saturation
of the 1st IF amplifier from strong signals outside the pass-band filter, and improves
the dynamic range in the presence of strong adjacent signals. 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.
The IC-7700 accommodates both the “on-the-fly” operator as well as the most avid
“tweaker” operator by providing tunable AGC preset and manual AGC level controls.
The AGC time constants can be set in the 3 presets (slow, medium and fast), adjustable
from 0.1–6 sec. (0.3–8 sec. in AM) delay. Then the addition of the AGC VR control
enables the user to “tweak” or fine tune the AGC reaction time.
High stability OCXO unit
Frequency
control of the IC-7700 is maintained by the high stability Oven Controlled Crystal
Oscillator. The OCXO achieves frequency stability of ±0.05ppm across the specified
temperature range, meaning that the frequency will deviate only 5Hz out of every
100 MHz! This specification is equivalent to that of specialized measuring equipment
such as signal generators or spectrum analyzers. Also, a 10MHz reference signal
can be input to the IC-7700 or output for use by external equipment.
The well-selected components provide premium performance
Mechanical relays
Mechanical relays using gold contacts have excellent deterioration resistance and
superior conductivity.
Hi-spec 1st IF filter
The IC-7700 uses custom made Hi-spec 1st IF filters (roofing filters), selected
especially for excellent IMD characteristics.
Large
coils
To reduce secondary distortion, large coils and capacitors are used in the high-amplitude
filter switching circuits. The use of non-linear semiconductors is minimized.
DSP
The transmitter and receiver use a 32-bit floating point DSP, offering
the high performance of 1800 MFLOPS processing. Also, the spectrum scope DSP achieves
1200 MFLOPS of peak performance.
Power
amplifiers
The power amplifiers use a combination of push-pull final with two MRF150
transistors, having proven reliability in ultra professional communications. These
devices generate a stable 200W of output power from HF to 54MHz.
7-inch wide color TFT LCD
While Icom’s RF engineering team reviewed receiver designs for how the IC-7700 hears
a signal, close attention was also paid to how the operator sees a signal. Details
such as response time, color, resolution, and visibility were extremely important.
Thus, an active matrix 7-inch (800 × 480 pixels) TFT color display was selected
as the IC-7700’s display. The display provides superior performance in response
time, color, resolution, visibility and more. The large display shows operating
frequencies, various settings and operating conditions as well as the spectrum scope,
S-meter and RTTY/PSK31 decoded messages. The S-meter shows an analog-like swinging
needle that is smooth and accurate. In addition to the analog like-style meter,
the IC-7700 has a digital multi-function graphic meter and edgewise meter - chose
your favorite style! Further more, the IC-7700 has a VGA connector for an external
monitor and an S-meter connector for an external analog S-meter.
USB ports on the front panel
Two
USB ports on the front panel allows you to easily connect a USB type keyboard or
USB memory stick to save transceiver settings, update firmware, or transfer settings
to other IC-7700. Making big scores means keeping your team fresh on those long
DX-peditions or Multi-Operators contests. Swapping out operators usually involves
time-wasting radio tweaks, because each operator has their own favorite settings
to best match their operating style. This all changes with the USB drives! Prior
to a contest, operators may record their preferred IC-7700 settings such as filter,
Digital Voice Recorder (DVR) memories, antenna settings, etc. When it’s their turn
to operate, simply insert their USB Drive into the IC-7700. In a flash, the IC-7700
is now “their rig”, and there’s nearly zero down time!
RTTY /PSK31 operation without PC connection
The IC-7700 has a built-in RTTY and PSK31 modulator/demodulator. By simply connecting
a USB key-board, you can immediately start enjoying these modes. In addition, you
can pre-program transmit messages in the internal message memory or a USB memory
stick and transmit them even without typing a message from a USB keyboard. Also,
received messages can be stored to a USB memory stick and transferred to your PC.
4 antenna connectors
The IC-7700 has 4 antenna connectors (ANT1 to ANT4) with an automatic antenna selector.
Once you program the operating bands in each antenna memory, the IC-7700 will automatically
select the antenna as you change the operating band. The usage type for each antenna
can be set for Tx/Rx use, Rx only* use and off
line. The antenna switch button allows you to change the operating antenna temporarily.
* Rx setting is available for ANT4 only.
Real time spectrum scope
With a dedicated DSP unit, the IC-7700 spectrum scope achieves 80dB of dynamic range
at the signal input level. It also improves the scope response time and signal resolution,
so that it is possible to accurately tune to the intended signal as you see it on
the spectrum scope screen. The spectrum scope range can be set independently from
the receiving frequency. You can monitor band conditions between the selected sweep
edges (Fixed mode), as well as sweep a selected band width centered on the receiving
frequency (Center mode). In addition, the scope has useful functions including scope
attenuator (10dB/20dB/30dB), 2 types of marker (Transmit, Receiver) and Max hold
function. The mini scope function is convenient for continuous monitoring even while
adjusting the set mode.
Digital twin PBT
The digital twin PBT eliminates interference and noise from signals above and below
your frequency by changing the IF filter bandwidth. The IF shift function allows
you to shift or move the IF passband to either side to more accurately receive the
signal. The passband width, shift direction and steps (50Hz) are graphically displayed
on the LCD. You can reproduce the signal as you like to hear it.
Digital IF filter
The DSP-based digital IF filter of the IC-7700
rejects signals out of the pass band, and keeps the desired signal free of any distortion
or degradation of quality. Depending on the operating situation, for example handling
a pile-up or receiving a very weak signal, you can flexibly change sharp and soft
filter shapes or reduce or shift the filter width, even while receiving a signal.
Manual notch filter and auto notch filter
The manual notch filter controlled by the DSP has extremely sharp characteristics
and provides more than 70dB of attenuation. The notch filter width is selectable
from 3 types, allowing you to select the suitable filter width for the operating
mode and band. It eliminates persistent beat tones without affecting the AGC loop
function. In addition, the automatic notch filter tracks and eliminates two or more
interfering signals such as beat signals and carriers or tones from digital signals.
Variable noise blanker
The noise blanker provides significant reduction of pulse-type noise. The noise
blanker allows you to change the threshold level as well as blank duration parameter
and attenuation level.
Noise reduction
The noise reduction separates the target signal from random noise components. By
using the excellent performance of the 32-bit floating point DSP, this separation
is made immediately without a delay and extracts signals from noise components.
The noise reduction suppression level is variable in 16 steps to adjust the balance
between the S/N ratio and clarity.
Digital voice recorder
The digital voice recorder (DVR) is a convenient function for contests, DX-peditions,
portable operation and even regular operation. Record your callsign, CQ, or other
station information into a memory. Easy-to-access independent “Record (REC)” and
“Play” buttons are on the front panel.
RX audio HPF/LPF setting
The IC-7700 has a separate RX HPF/LPF setting for each mode. The high-pass filter
and low-pass filter are adjustable for each mode.
S/P DIF interface
The IC-7700 has the S/P DIF optical digital
interface for audio output and modulation input. By connecting an external digital
device* through a connecting cable, flexible audio tuning is possible, while keeping
good sound quality.
* Third party connecting cable, PC with sound card supporting S/P
DIF, and software are required.
SSB data mode
When you narrow the IF filter passband to 500Hz or less in SSB mode or SSB-data
mode operation, the IC-7700 automatically selects special band pass filters (BPF).
The BPF has a very sharp edge like a CW filter for better rejection of interfering
signals. Along with the BPF setting, the IC-7700 has a 1/4-tuning step function
for easier tuning operation.
Firmware upgrade for maintaining the best performance
Icom will always provide the latest firmware for keeping the radio up to date. Just
download the latest firmware from the Icom web site whenever a new version has been
uploaded, and update your IC-7700 via the USB memory.
Please check;
http://www.icom.co.jp/world/support/download/firm/index.html
200W output power at full duty cycle, full power operation
The IC-7700 uses two MRF150 power amplifiers
connected in push-pull configuration. The power amplifiers provide a reliable 200W
of output power up to 54MHz. The effective quad cooling fan system makes it possible
to generate 200W full power output even during full duty cycle operation. The digital
PSN modulator using a DSP unit consistently reproduces an outstanding signal-to-noise
ratio, providing clean and clear transmission. The PA amplifier uses a 48V DC supply
to provide output power with low IMD on all bands.
Microphone equalizer and adjustable transmit bandwidth
The built-in audio equalizer has separate bass and treble adjustments for a total
of 121 combinations, so you can adjust the tonal quality of your voice as your want.
In addition, the transmit bandwidth is selectable from 100, 200, 300, 500Hz at the
lowpass edge, and 2500, 2700, 2800, 2900Hz at the high-pass edge, respectively.
Three types of high and low combinations can be stored in the memory as favorite
settings. With this flexibility of DSP-based waveform shaping, transmit audio quality
is adjustable to your preference.
High speed automatic
antenna tuner covering HF to 50MHz band
The high speed automatic antenna tuner automatically performs tuning operations
and memorizes the setting in 100kHz steps. Once the tuner memorizes the setting
depending on frequency, the tuner recalls the setting and matches the antenna instantly.
In addition, high-voltage parts allow you reliable, continuous 200W operation even
at high duty cycles.
Memory keyer
The IC-7700’s memory keyer has
4 channels with 55 characters for CW, 8 channels with 70 characters for RTTY and
8 channels with 70 characters for PSK31 operation. The memory keyer is convenient
for programming station information, calling CQ and call sign for a DX-pedition
or contest. Also, the CW memory keyer has other time saving functions such as automatic
repeat, serial contest number auto-counter, and Morse cut number functions.
Other features
[Antenna line]
- BNC type RX IN/OUT connectors for receiver antenna or external attenuator
[Receiver]
- General coverage receiver covers from 30kHz to 60MHz
(* Some frequency bands are not guaranteed, depending on version)
- 4-step attenuator (6/12/18dB and OFF)
- Twin peak audio filter for RTTY operation
[Transmitter]
- Low distortion RF speech compressor
- Tx monitor
- 50 CTCSS tone encoder and decoder
- All mode power control
- VOX capability (Voice operated transmission)
[CW]
- Multi-function electronic keyer with adjustable keying speed, dot-dash ratio and
paddle polarity and bug key function
- DSP controlled CW keying waveform shaping
- Frequency lock function for split operation
- The normal (default) CW carrier point is selectable from USB and LSB
- APF (audio peak filter) function with soft/sharp filter shape
- Double key jack system
- Full break-in function
- CW pitch control from 300 to 900Hz
- CW/AM auto tuning function
[Operation]
- Set mode function for flexible and speedy setting
- Memory pad stores up to 10 (or 5) operating frequencies
- Quick split function enables split operation with a single action
- SSB/CW synchronous tuning
- Single knob control from squelch volume to RF gain
- RIT and ∂Tx variable up to ±9.999kHz
- Quick RIT/∂TX clear function
- UTC/Local Clock and timer function
- 1Hz pitch tuning and 1Hz indication
- 101 memory channels with 10-character comment
- Built-in voice synthesizer announces operating frequency, mode and receiving signal
strength
- Programmed scan, memory scan, select memory scan, VSC scan and ∂F scan
- Auto tuning step function
- Band edge beep
- Main dial tension control and dial lock
- CI-V interface capability and RS-232C connector for PC connection
- BNC type Transverter connector
- Triple band stacking register
- FFT scope wave averaging function
- Screen saver function
Rear Panel View
- Antenna Connectors
- Ground Terminal
- Breaker Switch
- External Display Connector
(D-SUB 15-pin, VGA)
- Ethernet Connector
- CI-V Remote Control Jack
- RS-232C Connector
- Main Switch
- AC Power Cord Receptacle
- Receive Antenna Connector
- Transverter Jack
- External DC Output Jack
- S-meter Output Jack
- External Memory Keypad Jack
- External Speaker Jack
- ACC Sockets A/B
- Tx/Rx Control Jack (Relay)
- ALC Input Jack
- ALC Level Pot
- Key Jack
- S/P DIF In/Out Jacks
- Reference Frequency In/Out Jack