Icom IC-730 Instruction Manual page 7

3 – 10 HEADPHONES
Any good headphone set, including stereo type, that have
4-16 ohms impedance can be used. With the plug inserted
halfway into the PHONES jack, both the headphone and
speaker will operate. This is convenient when others wish
to listen in on the station, or you wish to record contacts
using a tape recorder connected to the headphone jack.
With a stereo headphone set inserted this way, however,
the headphone will lose the sound on one side. With the
plug inserted completely, only the headphone works.
3 – 1 COOLING FAN
The rear of the PA unit is designed to provide for adequate
cooling, but with 200 Watt in put the final stage produces
quite a bit of heat, and its temperature may rise during
prolonged transmissions. The fan is connected to a tem-
perature monitoring circuit which monitors the temperature
of the final stage. The fan operates as follows:
1. The fan does not operate in the receive mode.
2. When the temperature rises to a point (75°C) detected
by the monitor circuit the fan will operate during both
transmit and receive and much more rapidly to provide
additional cooling. At this time stop transmitting and
investigate the cause of overheating i.e., antenna mis-
match, etc. Correct the cause of the overheating before
starting to transmit again.
3 – 12 POWER SUPPLV
It is recommended that you use the IC-PS15 as a power
supply for base operation. If you wish to use another type
Cable connections
power supply make sure that it meets the voltage, current
requirements. Note carefully the overvoltage protection, for
a runaway regulator can destroy the I C-730; be especially
careful that more than 16 Volts cannot be supplied to the
transceiver. Do not connect the power supply, antenna,
accessory plug, or microphone with the Power Switch in the
ON position. Be especially careful not to transmit without an
antenna or dummy load hooked up. If the fuse blows
replace it with a 20 Amp fuse, only after fixing the cause. Do
not turn the Power Switch ON and OFF repeatedly for this
way cause the readout to mis-display. Should this occur,
turn the set OFF and wait for approximately 30 seconds
before turning it back ON.
3 – 13 CAUTIONS
As the unit has al ready been closely adjusted with highly
sophisticated measuring instruments, never taper with the
turnable resistors, coils, trimmers, etc.
C-MOS is used in the Logic unit as well as the PLL. C-MOS
I Cs are very susceptible to excessive static charges and
over current and care must be used when handling them.
Therefore, avoid touching the Logic unit and the nearby
circuitry unless absolutely necessary. When it is necessary
to check the circuitry, observe the following points.
Ground all measuring instruments, the soldering iron, and
other tools. Do not connect or disconnect the C-MOS I C
from its socket, or solder it when the power is on. Do not
apply voltage of less than -0.5 or more than +5 Volts to the
input terminals of the IC. DO NOT MEASURE WITH AN
OHM METER.
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