Icom IC-28A Instruction Manual page 14

Ш EXTERNAL SPEAKER
4-2 FIXED INSTALLATION
Ш CONNECTIONS
Ш ANTENNA
Ш COAXIAL CABLE
Ап external speaker plug is supplied with the IC-28A/E for use with
an optional external speaker if you feel you require one. The
external speaker impedance should be 4 — 8 ohms. The internal
speaker is disconnected when the external speaker is connected.
The SP-10 speaker is recommended for mobile use with the
IC-28A/E.
A stable AC power supply with a protective circuit is required for
base station use. Battery-operated power supplies are not suitable.
The PS-45 AC Power Supply with the OPC-102 interface cable are
recommended options.
Antenna performance is crucial for reliable radio communications.
For this reason, a 50 ohm directional antenna is well worth the extra
investment. A tremendous variety of fixed location antennas are
available from various manufacturers. Choose one most suited for
your needs.
Particularly in a fixed location installation where feedline lengths
are often longer than in a mobile installation, it is best to use coaxial
cable with the lowest loss available.
At 144MHz, a 50 foot length of military grade RG-58C causes a
loss of approximately 14 watts due to cable loss when using the
IC-28A/E. Ап equal length of military grade RG-8A causes only
approximately 6 watts loss due to cable loss. Therefore, simply by
using a better quality cable, the power reaching the antenna will be
about 19 watts instead of 11 watts.