Mic Gain Control - Icom IC-701 Instruction Manual

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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