Rtty Operation - Icom IC-701 Instruction Manual

access cover as follows:
VOX GAIN CONTROL
FULLY COUNTER-CLOCKWISE
ANTI VOX CONTROL
FULLY COUNTER-CLOCKWISE
VOX DELAY CONTROL
FULLY CLOCKWISE
Turn the VOX switch on the front pane! to the ON (down)
position. Leaving the T/R switch in the receive position
and without pushing the PTT switch, turn the VOX gain
control clockwise while speaking into the microphone. At
a certain point, the T/R switching circuit will be activated
by your voice. This is the proper position for the VOX
Gain control. Set the VOX Gain control at a level which
provides for T/R switching at your normal voice level.
Transmit-release time (the time delay before the set auto-
matically returns to receive when you stop talking) is
controlled by the VOX delay control. Turning the control
counter-clockwise makes the time shorter. Set it at a
position which is comfortable and which allows for short
pauses in normal speech.
Adjust the ANT! VOX control so that the VOX circuit is
not activated by sounds from the speaker by turning the
control clockwise while receiving a signal.
5-3 CW OPERATION
5-3-1 RECEIVING
For CW reception, set the MODE Select Switch to the CW
or CW-N position. Other switches and knobs are set the
same as for SSB reception. The Pass Band Tune circuit is
preset internally for CW reception, therefore, when the
MODE Select Switch is set at the CW or CW-N (CW
NARROW) position, the Pass Band tuning control on the
front panel is inactivated.
In addition to a crystal band pass filter, an audio active
filter is built-into this unit. When the MODE Select Switch
is set at the CW-N position, this audio filter is activated and
the total selectivity of CW reception is improved. Also,
with this filter, internal noise is reduced for comfortable
CW reception and an improved signal to noise (S/N) ratio.
5-3-2 TRANSMITTING
Insert the keyer plug into the KEY Jack on the rear panel
of the unit, and set knobs and switches as follows:
COMP CONTROL OFF (Fully counter-clockwise)
METER SELECT SWITCH Po POSITION
Other knobs and switches are set the same as for CW
reception.
By setting the T/R switch to Transmit, the transmit LED
is lit and shows that you are ready for CW transmission.
When you key the keyer, the meter needle moves and your
CW signal is transmitted. To decrease the transmitting
power, turn the COMP Control clockwise to ON and rotate
to adjust while watching the meter needle on the Po scale
for the desired output power.
5-3-3 CW MONITOR
When keying, the side tone oscillator circuit is activated
and a 900Hz tone is heard from the speaker. The loudness
of this tone is adjusted by rotative the CW MONI Control,
located under the access cover. Rotating the CW MONI
Control clockwise makes the tone louder. (In the receive
mode, this side tone is audible and can therefore be used
for Morse Code Practice, adjustment of the keyer, etc.)
To receive again, place the T/R switch in the receive
position.
5-3-4 SEMI BREAK-IN OPERATION
The IC-701 has Semi Break-In CW capability when using
the VOX function. When keying, the unit is automatically
set in the transmit mode. After keying, it is returned to the
receive mode, also automatically, after a given transmit-
release delay time constant. Leave the T/R switch in the
Receive position, and set the VOX switch in the ON (down)
position.
The transmit release delay time constant is set by adjusting
the CW DELAY Control located under the access cover.
Turning the CW DELAY Control clockwise will make the
transmit release time longer. Set for your keying speed.
5-4 RTTY OPERATION
For RTTY operation, a teletypewriter and a demodulator
(terminal unit) which is operational with audio input are
necessary. Any demodulator with 2125/2295Hz (narrow,
170Hz shift) or 2125/2975Hz (wide, 850Hz shift) filters
can be used with the IC-701. You can select NARROW or
WIDE shifts by setting the RTTY SHIFT Switch, located
under the Access Cover, to N or W. Fine adjustment of the
MARK frequency can be accomplished by rotating the
NARROW or WIDE variable resistors, located behind the
RTTY SHIFT Switch.
5-4-1 RECEIVING
Audio signals for the demodulator can be supplied from
Pin 4 of the ACC socket on the rear panel, or from the
PHONES jack on the front panel. The level of the audio
signals from Pin 4 of the ACC socket does not vary by
turning the AF GAIN Control.
Set the MODE Select Switch to RTTY. The frequencies
for NARROW shift are 2295Hz for MARK and 2125Hz for
SPACE. For WIDE SHIFT, they are 2975Hz for MARK
and 2125Hz for SPACE.
If you have an AFSK generator, set the MODE Select
Switch on LSB for RTTY operation. Then the frequencies
for NARROW SHIFT are 2295Hz for SPACE and 2125Hz
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