Icom IC-720 Instruction Manual page 9

1. MULTI-FUNCTION METER
When in the receive mode the meter acts as a S meter
regardless of the position of the meter select switch. Signal
strength is indicated on а scale of 51-59, and $9+20dB to
59+40аВ.
In the transmit mode the meter has three functions which
are selected by the Meter Select Switch (31) and the IC
Meter Switch inside the top access cover. They are as
follows:
Ic; Indicates the collector current of the final transistors.
Po; Indicates the relative output power. SWR can be
measured by placing the switch located inside the top cover
to the SWR position.
ALC; In this position the meter functions when the RF
output reaches a certain level.
2. RF POWER CONTROL
The ІС-720 has a built-in speech processor which is turned
on by turning the control counterclockwise, from the
COMP. off. (a click will be heard.) When on, it functions as
the RF Drive Control, as explained in the Mic Gain Control
paragraph. In CW, SSB and RTTY modes it operates as the
output level control of the ІС-720. When this function is
not desired the control should be turned completely clock-
wise until off, and a click is heard.
3. MIC GAIN CONTROL
Adjusts the level of modulation of the input of the micro-
phone. Clockwise rotation increases the microphones gain.
As input will vary with different microphones and different
voices the knob should be turned until the Multi-Function
Meter needle, set in the ALC mode, begins to move slightly
in the ALC zone. In SSB and AM modes when the RF
Speech Processor is in use the Mic Gain Control sets the
clipping limits, while the RF Power Control sets the RF
drive level to the maximum power level, where ALC starts
at the saturation point of the amplifiers.
4. POWER SWITCH
A push-lock type switch to turn the set on and off, when
the 1С-Р515 is used it also acts as the on/off switch for that
unit. When pushed again it will unlock and power is cut off
to all circuits, except the PA unit. (Note: When the
IC-BC10A is used power will also be supplied to the
memories.)
5. PHONES JACK
Accepts a standard 1/4 inch headphone plug for headphones
of 4 ~ 16 ohms. Stereo phones can be used without
modification.
6. MIC CONNECTOR
Connect the supplied microphone. If you wish to use
another microphone see the hookup diagram on page 4.
7. AF GAIN CONTROL
Controls audio in the receive mode, turn clockwise to
increase the level.
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8. RF GAIN CONTROL
Controls gain of the RF section in the receive mode. Сіоск-
wise rotation increases the gain, as the control is turned
counterclockwise the needie of the multi-function meter
will rise, and only signals that exceed the level indicated
will be heard. |
9. TRANSMIT/RECEIVE (T/R) SWITCH
This switch is for manually switching from transmit to
receive and vice versa. Set the switch to RECEIVE (out)
and the ІС-720 is in the receive mode. Set the switch to
TRANSMIT (in) and it switches to transmit. When the
VOX switch set to on the T/R switch must be in the
RECEIVE position.
10. VOX SWITCH
Turns the VOX on and off. in SSB mode switching is
accomplished by voice detection, in CW mode semi break-in
switching is provided.
11. TUNING RATE SELECT SWITCH
The Small Vernier marks on the tuning knob are changed to
correspond to 10Hz steps or 100Hz steps which is selected
by this switch.
12. PB TUNE (PASS BAND TUNING) CONTROL
Allows continuous tuning of the pass-band selectivity by
moving the filter up to 700Hz from the upper or lower side
in SSB, CW and RTTY. Not only improves selectivity, but
also can improve the audio tone. Normal position is in the
center (12 o'clock) position and is 2.3K Hz wide in SSB.
13. RIT CONTROL
Shifts the receive frequency +800Hz either side of the trans-
mit frequency. On is indicated by a LED lighting. Rotation
toward the + side raises receiver frequency, toward — the
opposite. If the tuning knob is moved one increment while
this control is on it will automatically be pulsed off. This
feature makes it unecessary to manually turn off the RIT
when changing operating frequencies. The shift of fre-
quency is not shown on the display.
14. TUNING SPEED BUTTON
Push this button and the Dial TS indicator lights and the
vernier marks on the tuning knob correspond to 1K Hz steps.
This turns off the 100Hz digit on the display. When the
control is turned off the transceiver reverts to its former
condition. THis control is conveninent for quick О5Ү65 over
a great frequency range.
15. DIAL LOCK BUTTON
After a frequency is set pushing this button will electroni-
cally lock the VFO, and the Dial Lock LED lights. To
change frequencies the button must be pushed again. Turn-
ing off the power will also release the dial lock, and clear
the displayed frequency.
16. TUNING CONTROL KNOB
Clockwise rotation increases the frequency, and counter-
clockwise the reverese. The frequency change is selectible
through the use of Tuning Rate Select Switch and the
Tuning Speed button.