Icom IC-230 Instruction Manual page 5

3.5
When adjusting your antenna, whether mobile or fixed, by all means follow the
manufacturer's instructions. There are some pitfalls to be aware of. For example, do
not attempt to adjust an antenna for lowest VSWR when using a diode VSWR meter not
engineered for VHF applications. Such readings will invariably have error of 40% or
more. Rather, use an in line watt meter similar to the Drake WV-4 or Bird Model 23
with VHF cartridge. Further, when adjusting a mobile antenna, do so with the motor
running preferably above normal idling speed. This will insure proper voltage level to the
transceiver. |
Do not become alarmed if your transceiver fails to transmit at times during the antenna
tune up procedure. Remember, your transceiver has a built-in Automatic Protection
Circuit (APC) that will disable the transmitter if excessive VSWR, a shorted coaxial line
or connector, or other antenna deficiency is present. A quick check on a good 50 ohm
dummy load will show the transceiver to be working. The difficulty will lie with the
antenna or its transmission line.
Microphone:
A high quality dynamic microphone is supplied with your transceiver. Merely plug it
into the proper receptacle on the front panel.
This microphone is of 500 ohms impedance with a normal output of 6 mV. Should you .
wish to use a different microphone, make certain it is of equal impedance and output
level. Under no circumstances use a "gain pre-amp" or ceramic type microphone. The
audio system in your transceiver is more than adequate and additional pre-amplification
unnecessary. To use this class of microphone is to invite distortion and possible damage
to the transceiver.