Icom IC-701 Instruction Manual page 16

effective in reducing interference from nearby signals.
For example, while receiving in the LSB mode, if you get
interference from a lower frequency (interfering signals are
high pitched tones), narrow the band width by turning the
P. B. tuning contro! counter-clockwise. When the interfer-
ing signals are low pitched tones, they are from a higher
frequency, and you should narrow the band width by
turning the P. B. tuning control clockwise.
When receiving in the USB mode, the band width is nar-
rowed in the opposite manner. Interference from a higher
frequency will be high pitched tones, and the P. B. tuning
control should be turned clockwise. Interference from a
lower frequency will be low pitched tones and the P. B.
tuning control is turned counter clockwise.
When P.8. TUNE knob is turned
counter-clockwise.
Receiving LSB signal
BFO frequency Pass band is narrowed
Receiving signal and interfering signal
goes out of the pass band.
interference
interfering signal
When P.B. TUNE knob is turned
clockwise.
Receiving LSB signal
ia interfering signal Pass band is narrowed
and interfering signal
BFO frequency ; ig signal
Interference
goes out of the pass band.
Receiving signal
This control can also be used for audio tone adjustment, so
it may be set for the most comfortable reception. The Pass
Band Tune functions only in SSB and RTTY, not in the
CW mode.
5-2-6 TRANSMITTING
Before transmitting, listen in the receive mode to make sure
your transmission will not interfer with other communi-
cations. If possible, use a dummy load for adjustment
instead of an antenna. Set knobs and switches as follows.
MIC GAIN CENTER
COMP CONTROL OFF (counter-clockwise til it
"clicks'')
METER SELECT SWITCH ALC
Other knobs and switches are Jeft in the same positions as
for receiving. When the T/R switch is moved to transmit,
or when the PTT (push to talk) switch on the microphone
is depressed, the transmit LED is illuminated. By speaking
into the microphone, the meter needle will move according
to the strength of your voice and SSB signals will be
transmitted. Set the MIC Gain control so that the meter
needie stays well within the blue ALC zone at voice peaks.
Now set the Meter Select switch to the Ic position. The
meter needle should be at about 300mA with no signals
into the microphone. Change to the receive mode by
moving the T/R switch to receive, or release the mi-
crophone PTT switch.
5-2-7 HOW TO USE THE SPEECH PROCESSOR
The IC-701 has a low distortion RF Speech Processor
built into the set. In equipment having tubes for the final
stage, using an RF Speech Processor causes concern about
possible tube damage caused by the increase in talk power.
However, since the |C-701 is completely solid state, includ-
ing the finals, and designed for heavy duty use, this worry
is eliminated. The RF Speech Processor also enables
greater talk power and better results in DX operation.
Follow the steps below for use of the RF Speech Processor:
MIC GAIN CONTROL
TURN FULLY CLOCKWISE
METER SELECT SWITCH
ALC POSITION
COMP CONTROL
TURN FROM THE OFF POSITION UNTIL IT
"CLICKS" ON
Switch to transmit and turn the COMP contro! slowly
clockwise while speaking into the microphone until the
meter needle moves within the ALC blue zone. (usually
_ about 2/3 clockwise)
Set the meter select switch to the COMP position. Speak
into the microphone while transmitting. Turn the MIC gain
control down (CCW) so that at the voice peaks, the meter
needle is close to '0'' on the COMP scale.
Further reduction of the MIC GAIN control to a point
where the meter just moves in both COMP and ALC
positions yields the best voice quality and maximum peak
(not average) power output.
The mic gain and compression levels vary on different
bands, so it will sometimes be necessary to repeat the above
procedures carefully for the best result.
The COMP control should be turned OFF or MIC carefully
set for minimum comp as below for all communications
other than DX operation for a very natural voice quality.
5-2-8 HOW TO USE THE VOX CIRCUIT
The IC-701 has a built-in VOX (voice operated relay) which
allows automatic T/R switching by voice signals into the
microphone. For VOX use, set the knobs inside the top
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