Icom IC-551D Instruction Manual page 26

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Other knobs and switches are left 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.
Hold the microphone about three inches from your mouth and speak in a normal voice.
The microphone is of the dynamic type and provides good pickup for all levels of voice.
Turning the MIC GAIN Control too high or speaking too loudly into the microphone does not
increase the RF output power, but causes some distortion in the SSB signals or spurious
radiation. 1f you wish to decrease the peak power, turn the RF POWER Control clockwise
beyond the "click" and adjust to obtain the desired RF output power of between 1 watt and
80 watts.
To receive again, turn the T/R switch to RECEIVE or release the PTT button. This will also
switch OFF the transmit indicator.
HOW TO USE THE SPEECH PROCESSOR
The Pass Band Tuning unit acts as a low distortion RF Speech Processor. This enables greater
talk power and better results in DX operation.
Follow the steps below for use of the RF Speech Processor:
MIC GAIN CONTROL Set to the CENTER (12 o'clock) position.
RF POWER CONTROL Turn from the "СОМР" OFF position until it
"CLICK" ON.
Switch to transmit and turn the RF POWER CONTROL clockwise while speaking into the
microphone until you obtain the desired RF "РЕАК" output power of between 1 watt and 80
watts.
Adjust the MIC GAIN CONTROL to a point where the RF "AVERAGE" output power just
saturates. |
Тһе Speech Processor should be turned OFF ог MIC GAIN CONTROL carefully set Тог mini-
mum compression for all communication other than DX operation for a very natural voice
quality. |
HOW ТО USE THE VOX CIRCUIT
The VOX (voice operated relay) unit allows automatic T/R switching by voice signals into the
microphone. For VOX use, set the knobs inside the top access cover as follows:
VOX GAIN CONTROL FULLY COUNTERCLOCKWISE
VOX DELAY CONTROL FULLY CLOCKWISE
ANTI VOX CONTROL FULLY COUNTERCLOCKWISE
Turn the VOX switch on the front panel 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 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 automatically returns to receive when you