Icom IC-701 User manual

\LL SOLID STATE
__ TRANSCEIVER
METER
WRICOM Ait sous state
ON/OFF ON
RECEIVE VOX
a-+ O 1°) o
AF GAIN~-®> AF GAIN P.B.TUNE TRANSMIT ON ON

SECTION
SECTION
SECTION
SECTION
4-1
4-2
4-3
SECTION
5-1
5-2
5-3
5-4
5-5
SECTION
6-1
6-2
6-3
6-4
6-5
6-6
SECTION
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Fe2
7-3
ie
SECTION
SECTION
SECTION
SECTION
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SECTION | SPECIFICATIONS
GENERAL
Number of Semi-Conductors:
Transistors 128
FET 23
IC (Includes LS!1) 56
Diodes 265
Frequency Coverage:
1.8MHz ~ 2.0MHz
3.5MHz ~ 4.0MHz
7.0MHz ~ 7.5MHz
(7.3MHz~7.5MHz Receive Only)
14.0MHz~15.2MHz
(14.35MHz~15.2MHz Receive Only)
21.0MHz~21.5MHz
28.0MHz~30.0MHz (28.0MHz~29.7MHz Transmit
Range)
Frequency Control:
LSI based 100Hz step Digital PLL synthesizer.
Independent Transmit-Receive Frequency Available
on same band.
TRANSMITTER
DC Input Power:
SSB (A3J) 200 Watts
CW (Ai), RTTY (Fi) 200 Watts
Continuously Adjustable Output power 0~Max.
Emission Mode:
A3J SSB (Upper sideband and Lower sideband)
Al CW
Fi RTTY (Frequency Shift Keying)
Harmonic Output:
More than 40dB below peak power output
Spurious Output:
More than 60dB below peak power output
Carrier Suppression:
More than 40dB below peak power output
Unwanted Sideband:
More than 40dB down at 1000Hz AF input
Microphone:
Impedance 600 ohms
Input Level 10 millivolts typical
Dynamic or Electret Condenser Microphone
Frequency Readout:
6 digit LED 100Hz readout.
Frequency Stability:
Less than 500Hz after switch on 1 min to 60 mins, and
less than 100Hz after 1 hour. Less than 1KHz in the
range of—10°C to +60 °C.
Power Supply Requirements:
DC 13.6V +15% Negative ground Current drain
18 A max. (at 200W input)
AC power supply speaker console is available for AC
operation.
Antenna !mpedance:
50 ohms Unbalanced
Weight:
7.3Kg
Dimensions:
111mm x 241mm x 311mm (H x W x L)
RECEIVER
Receiving System:
Triple Conversion Superheterodyne with continuous
Bandwidth Control
Receiving Mode:
Ai, A3J (USB, LSB) Fi (Output FSK audio signal)
IF Frequencies:
Ist 9.0115MHz
2nd 10.75MHz
3rd 9.0115MHz
with continuous Bandwidth Control
Sensitivity:
Less than 0.25 microvolts for 10dB S+N/N
Selectivity:
SSB. RTTY +1.2KHz at —6dB
(Adjustable to +0.5KHz Min)
+2.0KHz at —60dB
CW +250Hz at —6dB
+700Hz at —60dB
CW-N +100Hz at —6dB
+500Hz at —60dB (with Audio Filter)
Spurious Response Rejection Ratio:
More than 60dB
Audio Output:
More than 1.5 Watts
Audio Output Impedance:
8 ohms
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SECTION 2 FEATURES
ALL. BAND, ALL MODE, ALL SOLID STATE
The IC-701 covers all the Amateur HF frequencies from 1.8MHz to 29.999.9MHz plus 15MHz WWV. It offers not only
SSB, but also CW and RTTY. All of the circuits in the IC-701, including the driver and final power stages are completely
solid state, and provide about 100 Watts output.
COMPUTER COMPATIBLE TUNING SYSTEM
The local oscillator circuit (VFO) employs a C-MOS LSI! for the PLL that has been custom-made on the basis of ICOM’s
advanced digital technology. The VFO circuit is a digital PLL circuit that controls frequency determination by pulses
produced by the tuning control. Unlike conventional PLLs, it controls the VCO by combining and dividing crystal oscillator
frequencies. Therefore, its stability is much higher than conventional VFOs. In addition, the pulse control system makes
it possible to set and change frequencies with external digital signals.
With a computer programmed and connected to the rear accessory socket, you can easily control frequencies, change bands,
scan, on the IC-701. This system will give you the maximum of performance and versatility.
DUAL DIGITAL VFO’S
The IC-701 contains two built-in digital VFO’s located in ICOM’s custom LSI, providing the ultimate in versitility.
DIGITAL READOUT AND FULL METERING
The
frequency
is
presented
in
bright
easy
to
read
LEDs,
with
no
backlash
or
waiting
time.
The
mulit-function
meter
shows
you
relative
signal
strength
in
receive,
power
output,
ALC,
SWR,
compression
level,
final
transistor
voltage
and
current.
All
the
important
information
you
need
to
know.
PASS BAND TUNING AND SPEECH PROCESSOR
The
IC-701
has
a
built-in
Pass
Band
Tuning
system
developed
by
ICOM
that
allows
you
to
continuously
adjust
the
pass
band
of
the
IF.
By
turning
the
control,
you
can
eliminate
interference
from
a
nearby
signal,
thus
providing
clear
reception.
It
can
also
be
used
as
a
tone
control.
During
transmit,
the
Pass
Band
Tuning
circuit
can
be
used
as
a
Speech
Processor
providing
increased
“talk
power”
for
outstanding
D
Xing.
OUTSTANDING PERFORMANCE
The RF amplifier circuit using MOS FETs, the Schottky barrier diode balanced mixer and other circuits provide excellent
Cross Modulation and Two-Signal Selectivity characteristics. The IC-701 has excellent sensitivity demanded especially for
mobile operation, high stability, and with two Crystal Filters having high shape factors, exceptional selectivity.
The
Same
Schottky
diode
mixer
is
used
in
the
transmitter,
and,
with
the
band
pass
filter
and
high
performance
K-Constant
two
stage
low-pass
filter,
ensures
transmission
of
pure
signals
with
very
low
spurious
emission.
ADDITIONAL CIRCUITS
The IC-701 has a built-in Noise Blanker, VOX, an Auto Dimmer for control of the readout and meter illumination, CW
Monitor, APC, SWR detector, and many other circuits for your convenience.
The IC-701 has everything you need to really enjoy HF operation, in an extremely compact, rugged transceiver.
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SECTION 3
INSTALLATION
BE SURE TO READ THE FOLLOWING INSTRUCTIONS BEFORE USE.
3-1 UNPACKING
Carefully remove your transceiver from the packing carton
and examine it for signs of shipping damage. Should any
be apparent, notify the delivering carrier or dealer im-
mediately, stating the full extent of the damage. It is
recommended you keep the shipping cartons. In the event
storage, moving, or reshipment becomes necessary they
will be handy. Accessory cables, plugs, etc., are packed
with the transceiver. Make sure you have not overlooked
anything.
1. Microphone (1C-SM2) .......... 0.0. e eee eee eee 1
2. External Speaker Plug... .. 2.0.0... cc ee eee wees 1
Oe SCV FIUG* oo tack ne ieee an tee seek e te ee oe tee 1
4. Scope Terminal Plug........... 0.0.02 eee eens 1
5. Transverter terminal Plug .............005 0 eee 1
6. Spare Fuse (20 Amp) ........... 000 ee eee eeee 2
7; DG, Power Cord’. oe adie Set ied yee ee es 1
8. Accessory Plug (24 Pin) ............02 0c eee 1
GO: Accessory Plug PINs - 3-4 ewiiwat- ie oa ek Sat es 24
10. Accessory Plug Boot ............ 0c cece eee eens 1
3-2 RECOMMENDATIONS FOR
INSTALLATION
1. Avoid placing the IC-701 in direct sunlight, high
temperature, dusty or humid places.
2. The left side of the unit, when facing it, functions
also as a heatsink. The temperature there will usually
become relatively warm during transmission. Any
equipment should be at least 1 inch (83cm) away from
the unit so as to provide good ventilation. Be sure that
nothing is on and just behind the rear PA heatsink to
ensure good ventilation. Also avoid places near outlets
of heaters, air conditioners etc.
3. Place the unit so that the controls and switches can
easily be handled and the frequency indication and
meter can easily be read.
4. For mobile installation, an optional mounting bracket
is available. Select the best location that can stand the
weight of the unit and that does not interfere with your
driving in any way.
5. Use the Ground Lug!
3-3 POWER SUPPLY
For AC operation, use the special power supply !C-701PS.
If you would like to use your car battery or any other DC
power supply, be sure that its output voltage is 12-15 Volts
and the current capacity is at least 20 Amps. The maximum
power consumption of the set during transmission runs
from 16-20 Amps, so keep that in mind if the unit is
installed in your automobile, and turn it on after you have
started the engine. Attention should also be paid to the
condition of the battery and electrical system.
The connection of the DC power cord supplied with the
1C-701 is done in the following way: First make sure that
the power switch of the unit is in the OFF position and
the T/R switch is in the receive position. Connect the cord
to the DC power supply with the RED lead to the positive
terminal and the BLACK lead to the negative terminal.
(Reverse connection will cause the protection circuit to
operate and blow the fuse.) Connect the DC plug to the
socket on the rear panel of the !C-701. Refer to the
drawing below.
a
seas
O
A
|
1C-701PS
:
pSeRR ER RESEREREESES AC POWER
OUTLET
For AC operation
BATTERY
or
De POWER SOURCE
DC POWER CORD
For DC operation
3-4 ANTENNA
Antennas play a very important role in radio communi-
cation. If the antenna is inferior, your transceiver cannot
give you the best performance. With a good antenna and
feeder cable having 50 ohm impedance, you should easily
get the desired matching and performance. Carefully install
a high performance antenna that suits the frequency
band(s) you wish to operate on and place it as high as
possible. Be especially careful of the condition of the
connectors as loose connections will deteriorate the per-
formance. Be sure to connect the ground terminal of a
whip antenna, if used, to the body of your car.
As the output is quite high, avoid connecting the antenna
connector to open lines and do not transmit under
mismatched conditions. Otherwise the final stage could be
overloaded and cause a malfunction of the unit.
—-3-
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3-5 GROUND
In order to prevent electrical shocks, TVI, BC! and other
problems, be sure to connect a heavy wire ground, as
short as possible, from a good earth point to the ground
terminal on the rear panel.
3-6 MICROPHONE
The microphone supplied with the IC-701 is the IC-SM2
which contains a pre-amplifier. It’s circuit diagram is shown
below. The IC-SM2 is an Electret Condenser type
microphone.
Schematic diagram of IC-SM2
R7 200M
(2)
° 3 3 7] ° o
°
TR1, TR2: 2SC536 or equivalent
A sensitivity contro! is installed on the bottom side of the
mic stand. By turning it in the “’H” or “L” direction, the
sensitivity will increase or decrease respectively. Adjust the
control so as to get the proper sensitivity considering the
distance to the mic, the loudness of your voice and the
environmental conditions. The wind screen not only
prevents background noise due to wind, but also protects
the mic. Unless required, do not remove the screen from
the mic. In order to operate the microphone, connect its
plug to the mic socket on the IC-701. To transmit, press
the PTT switch downward. When it is released, the IC-701
will return to the receive condition. For a long transmis-
sion, pull the PTT switch back while pressing it down until
the switch is locked and it will remain in that position until
it is pushed forward and released.
LOCK RELEASE
Key Wiring Diagram
If you would like to use a different microphone in your
car, an optional hand held dynamic microphone is available.
If other types of microphones are used, be sure their
impedance is between 500-600 ohms, and connect a 4 pin
plug in the manner shown.
Microphone plug exploded view
Microphone connection
Microphone
(cord side view)
3-7 CW KEY
When operating CW, connect the Key to the Key Jack with
the plug supplied. The connection of the plug is shown
below.
If the terminals have polarity, be sure to make the correct
connection.
Note
that
the
keyed
voltage
when
switching
with semiconductors or relays with resistors in the circuit,
should be adjusted to be below 0.4 Volts!
3-8 RTTY
When operating RTTY, connect the ACC socket pins 8
(ground)
and
9
to
your
tele-typewriter
through
a
high
speed
relay or a level converter to TTL level, and the tones for
your
terminal
unit
will
be
available
from
pin
4.
For
details,
refer
to
“How
to
use
RTTY”,
and
“Transmit
and
Receive”’
sections in this manual.

3-9 EXTERNAL SPEAKER
The IC-701 contains an internal speaker, and is also
designed so that it can drive an external speaker from the
external (EXT) speaker jack on the rear panel. Be sure the
impedance of the external speaker is 8 ohms, and remember
that with the external speaker connected, the internal
speaker is disabled.
3-10 HEADPHONES
Any good headphone set, including stereo type, that have
4-16 ohms impedance can be used. With the plug inserted
halfway into the PHONES jack, both the headphone and
speaker will operate. This is convenient when others wish
to listen in on the station, or you wish to record contacts
using a tape recorder connected to the headphone jack.
With a stereo headphone set inserted this way, however,
the headphone will lose the sound on one side. With the
plug inserted completely, only the headphone works.
3-11 POWER SUPPLY
It is highly recommended that you use the [C-701PS power
supply for base operation. If you wish to use another
power source, make sure that it meets the voltage, current,
and regulation requirements. Pay particular attention to
the overvoltage protection as a runaway regulator can
destroy the IC-701. Make certain that more than 18 Volts
does not get applied to the unit. When the power switch
is in the ON position, do not connect the power cord,
antenna, external speaker, Accessory plug, or the mi-
crophone to avoid possible trouble. Be sure not to transmit
with the antenna disconnected. If the fuse blows, replace
it with a new 20 Amp fuse after fixing the cause. Avoid
turning
the
power
switch
ON
and
OFF
repeatedly
over
a
short time. Frequent repetitions may cause the frequency
indicator to display the wrong frequencies. If such a
malfunction should occur, turn OFF the switch and a few
seconds later turn it ON again.
3-12 CAUTIONS
As the unit has already been closely adjusted with highly
sophisticated measuring instruments, never tamper with
the turnable resistors, coils, trimmers, etc.
IN THE PLL UNIT, THE HEART OF THE TRAN-
SCEIVER, A C-MOS LSI IS INCORPORATED. IF THE
SEAL IS BROKEN WHEN A FAILURE OCCURS WITHIN
THE TERMS OF THE GUARANTEE, THE REPAIR
MAY BE AT THE USERS EXPENSE, SO DO NOT
ATTEMPT TO OPEN THE PLL CASE!
C-MOS is also used in the digital driver unit as well as the
PLL. C-MOS ICs are very susceptible to excessive static
charges and over current and care must be used when
handling them. Therefore, avoid touching the driver
unit and the nearby circuitry unless absolutely necessary.
When it is necessary to check the circuitry, observe the
following points.
Ground all measuring instruments, the soldering iron, and
other tools. Do not connect or disconnect the C-MOS IC
from its socket, or solder it when the power is ON. Do
not apply voltage of less than —0.5 or more than +5 Volts
to the input terminals of the IC. DO NOT MEASURE
WITH AN OHMMETER.
3-13 COOLING FAN
The rear of the PA unit is designed to achieve effective
natural cooling. But with 200 Watts input, the final stage
circuit produces quite a bit of heat and its temperature may
rise during a very long, continuous transmission. If the
temperature becomes high enough, the built-in cooling fan
will start to spin. The fan is connected to the temperature
monitoring circuit which detects the temperature of the
final stage transistors. The operation of this fan is as
follows:
1. The fan does not work during all reception.
2. During transmission, it does not work if the detected
temperature is below a certain level.
3. When the temperature exceeds that level during a
transmission, the fan will start to move air across the
heatsink to cool it.
4. If the temperature of the final stage transistors rises to
the danger point, the fan will turn at a much higher
speed and frequency display will start to flash.
THIS MEANS STOP TRANSMITTING!
1, 2 and 3 are normal conditions. 4 is abnormal. If the
meter and display start to flash, stop transmitting and
check for the cause of the excess heat. This could be
antenna mismatch, environmental problems, etc., but be
sure to rectify the problem before beginning to operate
again.
—5—
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SECTION
4
OPERATING
CONTROLS
4-1 FRONT PANEL
@ DIAL LOCK INDICATOR LED
@ FREQUENCY DISPLAY
@ DIAL TS INDICATOR LED
@ TRANSMIT INDICATOR LED
@ MULTI-FUNCTION METER
78 5 ALC Po
ef ee COMP 4.4 “io
35 Sm!
> aT
@
BAND
SWITCH
en
mr
(.
@®
METER
SELECT
whe
SWITCH
rd
@ POWER SWITCH
® PHONES JACK—33
® MIC CONNECTORS
/ 4
WB. TINE /’
fj i
@ COMP (SPEECH
PROCESSOR)
CONTROL
@® MIC GAIN CONTROL
@ AF GAIN CONTROL
@ RF GAIN CONTROL
@ MODE SELECT
SWITCH
(PASS BAND TUNING
( VFO SWITCH
@ RIT CONTROL
1. BAND SWITCH
The BAND SELECT SWITCH is a 7 position rotary switch
used for selecting one of the 6 Amateur bands covered by
the IC-701 with a 7th position for external control.
The selectable bands are 1.8MHz, 3.5MHz, 7MHz, 14MHz,
21MHz and 28MHz. In the EXT position, the band can
be selected remotely. However, the switch should not be
put in the EXT position without having the remote control
connected. This will cause the rotary switch to rotate
continuously and may cause excessive wear or damage.
2. MULTI-FUNCTION METER
With the {C-701 in the receive mode, this meter acts as an
S meter regardless of the position of the meter select
—-6-—-
11c-70O8
8 RATB -
. Lo SBR pit NB oRaC
ee,
@ DIAL LOCK BUTTON
@ TUNING CONTROL
KNOB
@ TUNING SPEED BUTTON
12 AGC SWITCH
@ ATTENUATOR SWITCH
(® NOISE BLANKER SWITCH
(9 VOX SWITCH
1) RIT SWITCH
@ TRANSMIT/RECEIVE SWITCH
switch. Signal strength is indicated on a scale of $1-S9
and $9+20dB to S9+60dB.
In the transmit mode, the meter has 5 functions as outlined
below which are selected by the meter select switch.
3. METER SELECT SWITCH
In the transmit mode the meter has 5 functions.
1. Ve Indicates the collector voltage of the final
transistors.
2. Ic Indicates the collector current of the final
transistors.
3. Po Indicates the relative output power. SWR can
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be measured by placing the SWR/SWR SET
switch in the SWR position. (This switch is
located under the access cover on the top of
the IC-701.
4. ALC In this position, the meter begins to function
when the RF output power reaches a certain
level.
5. COMP Indicates the compression level when the speech
processor is in use.
4. POWER SWITCH
The POWER SWITCH is a push-lock type switch which
controls the input DC power to the IC-701. When the
external AC power supply (IC-701PS) is used, the switch
also acts as the AC power supply switch. When the switch
is pushed in and locked, power is supplied to the set. When
the switch is pushed again and released, power is cut to all
circuits except the PA unit.
5, PHONE JACK
This jack accepts a standard 1/4 inch headphone plug for
a 4-16 ohm headphone set. Stereo headphones can be
used without modification.
6. MIC CONNECTOR
Connect the supplied microphone or optional microphone
to this jack. If you wish to use a different microphone
than the IC-SM2, refer to the drawing on page 4. Mic-
rophone impedance should be 500-600 ohms.
7. COMP (SPEECH PROCESSOR) CONTROL
The IC-701 contains a built-in RF speech processor which
is turned ON by turning the center knob clockwise from
the OFF position (a click will be heard). In the ON position
it works as the RF drive control as explained below. In
the CW and RTTY modes, it works as the output level
control of the IC-701. When RF speech processor
operation is not desired, the COMP control should be
turned completely counter-clockwise and clicked OFF.
8. MIC GAIN CONTROL
Adjusts the level of modulation according to the input of
the microphone. Clockwise rotation increases microphone
gain. As the input will vary with different microphones
and different voices, the knob should be turned until the
MULTI-FUNCTION METER needle, in the ALC mode,
starts to move slightly within the ALC zone. In the SSB
mode, with the RF speech processor in use, the MIC
GAIN CONTROL sets the clipping limits, while the COMP
control sets the RF drive level up to the maximum power
level where ALC begins at the saturation point of the
amplifiers.
9. AF GAIN CONTROL
Controls the audio output level in the receive mode.
Clockwise rotation increases audio output.
10. RF GAIN CONTROL
Controls the gain of the RF section in the receive mode.
Clockwise rotation gives the maximum gain. As the
control is rotated counter-clockwise, the needle of the
MULTI-FUNCTION METER rises, and only signals stronger
than the level indicated by the needle will be heard.
11. MODE SELECT SWITCH
This switch selects the mode of operation for both
transmit and receive.
USB Upper Sideband, mainly for 14, 21 and 28MHz
bands.
LSB Lower Sideband, mainly for 1.8, 3.5 and 7MHz
bands.
CW Continuous Wave, for CW operation on all bands.
~CW-N Narrow CW. The audio band-pass filter is auto-
matically turned ON in this position to improve
selectivity when receiving.
RTTY Radio Teletype. For use on all available bands.
12. P. B. TUNE (PASS BAND TUNING) CONTROL
This control allows continuous tuning of the pass band
selectivity moving the edge of the filter up to 1.5KHz from
either the upper or lower side in SSB and RTTY. This not
only improves selectivity, but also can improve the audio
quality. The normal position is in the center (12:00
o'clock) position and is 2.4KHz wide in SSB.
13. VFO SWITCH
With this switch you can select the VFO you want to
operate from two separate VFO’s that are built-in to the
IC-701. It also selects the relationship of the two VFO’s.
The switch performs the following operations according
to its position.
* A: Selects ““A’’ VFO for both transmit and receive.
* B: Selects ‘“B’’ VFO for both transmit and receive.
* RA-TB : Selects ‘““A’’ VFO for receive and ‘B’’ VFO for
transmit.
* RB-TA: Selects ‘‘B’’ VFO for receive and “A’’ VFO
for transmit.
In addition, when the VFO is switched from “‘A’’ VFO to
“B’ VEO, the frequency indicated on the frequency
display just prior to switching goes into a memory inside
the LSI. Thus even if ‘“B’’ VFO is being used, switching
to “A” again will enable you to operate at the initial
frequency. Switching from “‘B” to “A” results in the
same operation. However, if switching is done with the
BAND SWITCH (or external control), the VFO frequency
displayed will disappear and the lower end frequency of
the band selected will be displayed. If you wish to operate
on the frequency that was memorized in the VFO that
was not used when switching bands, simply return to the
original band and then to the other VFO and the initiall
memorized frequency will appear.
more detail later in this manual.
This is explained in
14. RIT CONTROL
Shifts the receiver frequency +800Hz either side of the
transmit frequency. When the RIT is ON, the RIT LED is
illuminated. The LED also represents the ‘‘0’’ position.
Rotating the control to the (+) side raises the receiver
frequency, and rotating to the (—) side lowers the receiver
frequency. With the RIT ON, if the tuning knob @j) is
moved one increment, the RIT circuit is automatically
pulsed OFF. Therefore it is not necessary to manually turn
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OFF the RIT when changing operating frequency. The
frequency shift by tuning the RIT Control is not indicated
on the frequency display.
15. RIT SWITCH
This is a spring-loaded switch for the RIT control. To
turn ON the RIT, push down once. If OFF is desired, push
down again. When the RIT is ON the LED above the RIT
control knob is lit. This also indicates the center position
of the RIT control. With the RIT circuit OFF the LED
is also OFF. Also if the RIT is ON and the Tuning Knob
is rotated one increment it will pulse the RIT OFF unless
the internal jumper has been changed.
16. NB (NOISE BLANKER) SWITCH
When pulse type noise such as automobile ignition noise is
present, set this switch to the ON (down) position. The
noise will be reduced to provide comfortable reception.
17. AGC (AUTOMATIC GAIN CONTROL) SWITCH
With this switch you can change the time constant on the
AGC circuit. With the switch in the AGC (up) position,
the circuit operates as a ‘“hang’’ AGC and maintains the
AGC voltage for a specific time, thus it is suitable for SSB
reception. With the switch in the FAST (down) position,
the circuit is OFF, and AGC is suitable for stations suffering
from fast fading or operating in the CW mode.
18. TRANSMIT/RECEIVE (T/R) SWITCH
This switch is for manually switching from transmit to
receive and vice versa. Set the switch to RECEIVE (up)
and the !C-701 is in the receive mode. Set the switch to
TRANSMIT (down) and it switches to transmit. When
switching with the PTT switch on the microphone or with
the VOX switch set to ON the T/R switch must be in the
RECEIVE position.
19. VOX SWITCH
This switches the VOX circuit ON and OFF. When it is
in the ON (down) position, in SSB, T/R switching is
accomplished by means of a voice signal. !n CW operation,
semi-break-in switching by means of keying is possible.
20. ATT (ATTENUATOR) SWITCH
Turn the ATT switch ON (down) when strong nearby
signals disturb signal reception or make “’S” readings
difficult. in the ON position, a 10dB attenuator is inserted
into the receiving antenna circuit, reducing interfering
signals and giving more stable reception. In normal
operation the ATT switch is left in the OFF (up) position.
21. TUNING CONTROL KNOB
Rotating the TUNING CONTROL KNOB clockwise in-
creases the frequency, while rotating it counter-clockwise
decreases the frequency. The frequency is changed in
100Hz steps which correspond to the smaller vernier
marks on the knob. The larger marks represent 1KHz
steps. One complete rotation of the tuning knob results in
a 5KHz frequency increase or decrease in 100Hz steps
exactly as shown by the small vernier marks.
22. TUNING SPEED BUTTON
Pushing the TUNING SPEED BUTTON will illuminate the
DIAL FAST display LED, and the small vernier marks on
the tuning knob are changed to correspond to 10KHz steps.
At the same time, the 1KHz and 100Hz digits are cleared
on the display to show ‘0.0’... When the Tuning Speed
Button is depressed again, the dial fast display LED goes
OFF and the small vernier marks will again correspond to
100Hz steps. This button will allow you to quickly QSY
over a great frequency range.
23. DIAL LOCK BUTTON
After the IC-701 is set to a certain frequency for rag
chewing, mobile operation, etc., pushing the DIAL LOCK
BUTTON will illuminate the DIAL LOCK display LED
and the VFO is electronically locked at the displayed
frequency, thus inactivating the operation of the tuning
knob. To change frequency, the dial lock must first be
disengaged by pushing the dial lock button again. The dial
lock display LED will go OFF and the frequency will
change with the direction of the tuning knob rotation.
Turning the power OFF will release the dial lock and clear
the displayed frequency.
24. FREQUENCY DISPLAY
The frequency of the IC-701 is displayed on 7 segment
LEDs. Since the 1MHz and 1KHz decimal points are
displayed, the frequency can easily be read. The fre-
quencies indicated are the carrier frequencies of each mode
in USB, LSB and CW. In the RTTY mode, the space
frequency is displayed. Since the local oscillation frequency
is shifted in accordance with modes, no tuning will be
required if you change modes. Remember, if you turn
the RIT control ON to change the receive frequency and
rotate the RIT control knob, the frequency displayed will
not change.
25. TRANSMIT INDICATOR LED
When your set is in the transmit mode, this LED is lit.
26. DIAL TUNING SPEED INDICATOR LED
illuminates when the TUNING SPEED BUTTON is pressed
to set the dial to fast tuning.
27. DIAL LOCK INDICATOR LED
illuminates when the DIAL LOCK BUTTON is pressed
to lock the dial.
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