Icom IC-720A Instruction Manual page 16

then set the large increment оп the tuning scale to line up
with the indicator arrow and then push the dial lock button
again.
The tuning knob scale may require recalibration if you:
1. Turn the knob while the frequency is locked by use of
the Dial Lock Button.
2. Turn the knob beYond the band edge.
Brake Adjustment
if the knob is too loose or too stiff for comfortable use,
уо can adjust the torque by tightening or loosening the
brake adjustment screw accessible from underneath the set.
Brake adjustment screw
The following instructions should be used to adjust the
tension of the Tuning Knob.
1. The Tuning knob tension will become tighter by turning
the brake adjustment screw clockwise, and will become
looser by turning the screw counterclockwise.
. While performing this adjustment, the Tuning knob must
be turned continuously as the screw is adjusted in order
to set the tension for a comfortable touch.
On all HAM bands except the 28MHz band, the displayed
frequency will not go beyond the highest band edge even by
turning the tuning knob clockwise, or beyond the lowest
band edge by turning the knob counterclockwise. On the
28MHz band, since this band width is much wider than the
others, the 1С-720А provides "automatic revert" over either
MHz for operating convenience. When the frequency dis-
play shows 28.999.9MHz and the tuning knob is turned
clockwise, the displayed frequency jumps down to 28.000.0
MHz and continues up from there. Likewise, by continuing
to turn counterclockwise beyond the bottom edge of the
band, the frequency jumps up from 28.000.0MHz to
28.999.9MHz and goes down from that point. The same
holds true for the 29MHz segment, and the general coverage
mode.
The frequency range of each band in the HAM band mode
is shown in the following chart.
In the GENERAL COVERAGE mode, the frequency range
is ".000.0" to .999.9" of each MHz.
-13-
Егедиепсу Вапае |
1.800.0 ~ 1.999.9
3.500.0 ~ 4.099.9
6.900.0 ~ 7.499.9
9.900.0 ~ 10.499.9 |
13.900.0 ~ 14.499.9
17.900.0 ~ 18.499.9 |
20.900.0 ~ 21.499.9
24.500.0 ~ 25.099.9
а
Тһе displayed frequency shows the carrier frequency іп the
USB, LSB, AM and CW modes, and the Mark frequency in
the RTTY mode.
5-1-3 TUNING RATE SELECT SWITCH
Pushing the Tuning Rate Select switch will change the basic
tuning rate of the set. In its normal out position the tuning
rate is 100Hz. When pushed in the tuning rate becomes
10Hz. The 10Hz may be read from the increments on the
tuning knob.
5-1-4 TUNING SPEED BUTTON
Pushing the Tuning Speed Button will illuminate the Dial
TS Indicator and the tuning rate is changed to correspond
to 1KHz steps. The last significant-digit on the display is
blanked. When the Tuning Speed Button is depressed again,
the Dial TS Indicator goes OFF and the tuning rate will
again correspond to 100Hz (10Hz) steps. This button will
allow you to quickly О5У over a great frequency range.
5-1-5 DIAL LOCK BUTTON
After the IC-720A is set at a certain frequency for гад chew-
ing, mobile operation, etc., pushing the Dial Lock button
will illuminate the Dial Lock Indicator and the VFO is
locked at the displayed frequency, thus inactivating the
operation of the tuning knob. To change the frequency,
the Dial Lock must first be disengaged by pushing the Dial
Lock button again. The Dial Lock Indicator will go OFF,
and the frequency will change with the direction of the
tuning knob rotation. Turning OFF the power will release
the Dial Lock.
5-1-6 VFO SWITCH
The CPU in the ІС-720А contains two "МЕО5" for both
receiving and transmitting. The МЕО" are labeled "А"
VFO and "B" VFO and are selectible with the VFO Switch.
This dual VFO system gives the IC-720A many very con-
venient features. Please read this section very carefully and
perform the operation several times until you are com-
fortable with the system.
1. "А" VEO is for both transmitting (ham bands only) and
receiving and is selected by placing the VFO switch in
the "A" position. The transmit and receive frequency
will be controlled by "А" VFO, displayed on the fre-
quency readout, and stored in "А" memory.