Icom IC-720 Instruction Manual page 6

3-4 MEMORY BACK-UP
To retain the memory in the CPU, keeping the operating
frequencies of the VFOs even when the main Power Switch
is turned off, hook up a power source of 9 to 12 Volts DC
to the Memory Back-Up terminal on the rear panel. For
mobile installation this can be accomplished by direct
connection to the car battery, since the current drain is low.
For AC operation it is recommended that the optional
BC-10A be used.
3-5 ANTENNA
The antenna is the single most important piece of equip-
ment, other than the transceiver. An inferior antenna will
result in reduced performance. With a quality antenna and
a feed of 50 ohms impedance matching the excellent per-
formance are easily attained.
Install a high performance antenna for the band(s) on which
you wish to operate, placing it as high as possible, and
insuring that all connections are securely made. Loose
connections, poor soldering, or faulty connectors will
greatly effect performance. In the case of mobile antennas
make sure they are connected to a good ground on the
body of the car.
The output of the transceiver is quite high so make sure
you do not connect the antenna connector to open lines or
transmit under mis-matched conditions. To do either can
result in overload of the final stage and damage or malfunc-
tion of the set.
WARNING:
DO NOT OPERATE THE SET WITHOUT A WELL-
GROUNDED ANTENNA TO PROTECT THE TRAN-
SCEIVER AGAINST MIS-MATCH. USE OF A BALUN
FOR MATCH 15 HIGHLY RECOMMENDED. FAILURE
TO DO SO CAN RESULT IN DESTRUCTION OF FINALS.
3-6 GROUND
To eliminate the danger of electrical shocks, ТУІ, BCI, and
other problems be sure to connect a heavy ground wire, as
short as possible, to the ground lug on the rear panel.
3-7 MICROPHONE
The microphone supplied with the ІС-720 is the |С-НМ7
which contains а pre-amplifier. The optional electret
condenser type stand microphone IC-SM5 can be used.
(The optional IC-SM5, а desk top type microphone also
contains also a pre-amplifier.)
Their circuit diagrams are shown below.
Schematic diagram of 1C-HM7
TR 25066!
(cord side
view)
| Schematic diagram of ІС-5М5
P.T.T. РЕ |
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6) ад
(cord side view)
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Should you wish to use a different microphone make
Certain it has a proper pre-amplifier.
Particular care should be exercised in wiring, as the internal
electrical switching system is dependent upon it. See the
schematic for the proper hook up.
Microphone plug exploded View