Icom IC-701

the setting of the RIT contro! knob.
When the RIT circuit is ON, if the tuning knob is moved by
one increment, the RIT circuit is automatically pulsed OFF.
However, this function can be eliminated by changing the
connecting pins in the driver unit as shown below, in
case you would like the RIT to remain operational when
you turn the tuning knob. Or, by continuously depressing
the RIT switch with your finger while turning the tuning
knob, the RIT circuit will remain operational while tuning.
Other things to remember are: The RIT circuit is ope-
rational when the frequency is locked with the dial lock
button. The frequency shifted by turning the RIT control
is not indicated on the frequency display. When the
transmitting and receiving frequencies differ by more than
800Hz, use “A” and “’B’’ VFQs as outlined previously. »
5-2 SSB OPERATION
5-2-1 RECEIVING:
After connecting an antenna, microphone, etc., set knobs
and switches as follows.
POWER SWITCH OFF
T/R SWITCH RECEIVE (UP)
VOX SWITCH OFF (UP)
ATT SWITCH OFF (UP)
AGC SWITCH SLOW (UP)
NOISE BLANKER (NB) SWITCH OFF (UP)
MODE SELECT SWITCH USB or LSB
VFO SWITCH
BAND SELECT SWITCH
AF GAIN CONTROL
RF GAIN CONTROL
P.B. TUNE CONTROL
RIT CONTROL
“AO or "BY"
Desired Band
Completely Counter-clockwise
Completely Clockwise
Center (12 o'clock) position
Center (12 o’clock) position
The other knobs are unrelated to receiving and need not
be set at this time.
In SSB operation there is both an USB (upper side band)
and an LSB (lower side band). LSB is usually used on the
1.8, 3.5 and 7MHz bands, while USB is usually used on the
14, 21 and 28MHz bands. Select the mode according to
the band in which you wish to operate.
Now turn ON the power switch. The meter lamp will be
illuminated and the lowest frequency of the selected band
will be shown on the LED readout. Slowly turn the AF
gain contro! clockwise to a comfortable level. Rotate the
tuning knob until a signal is received. The multi-function
meter needle will move according to the signal strength, so
tune for the highest possible meter reading and the clearest
audio. If you cannot get a clear signal, you may be receiv-
ing in the opposite sideband. {f so, change the mode switch
to the proper sideband.
The VFOs in the IC-701 change in 100Hz steps. Therefore
the maximum possible difference in your receiving fre-
quency and the received signal frequency is 50Hz. However,
for normal voice signal reception, a difference of 50Hz is
negligible and indeed may be hard to distinguish. Since the
frequency is changed in 100Hz steps with the IC-701, as
opposed to continuous variable frequency systems, tuning
is simplified and more accurate.
5-2-2 NB (NOISE BLANKER)
Turn the noise blanker ON (down) when there is pulse type
noise, such as ignition noise from automobile motors.
Noise will be suppressed and even weak signals will be
received comfortably. The noise blanker may not work as
effectively when there is a strong signal on a nearby fre-
quency or when there is continuous (not pulse type) noise.
5-2-3 AGC (AUTOMATIC GAIN CONTROL)
The IC-701 has a ‘‘hang’’ AGC system which holds the peak
voltage of rectified AF signals from the detector circuit for
a certain period. Therefore, during the pauses in normal
speech of the received signal, uncomfortable noises will not
be heard. The multi-function meter indicates the peak
value for a certain period, facilitating reading of the meter
“S" function.
For normal SSB reception, set the AGC switch in the UP
(slow) position. Set the AGC switch in the FAST (down)
position, when tuning or receiving signals with short interval
fading. When in the FAST position, the hang AGC circuit is
turned OFF and the time constant is shortened. Use the
FAST position for RTTY reception.
5-2-4 ATT (ATTENUATOR) SWITCH
Turn the ATT switch ON (down) when strong nearby
signals disturb signal reception or make “S’’ reading dif-
ficult. 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.
5-2-5 P.B. (PASS BAND) TUNING
Pass Band Tuning is a system in the receive mode to narrow
the band width (selectivity) of the frequencies that will pass
through the crystal filter electrically from either the upper
or flower side continuously by up to 1.5KHz. This is very
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