Preamp; Attenuator; Agc Time Constant; Antenna Selection - Icom IC-R75 Instruction Manual

5
RECEIVE FUNCTIONS

■ Preamp

The preamp amplifies received signals in the front
end circuit to improve the S/N ratio and sensitivity.
Turn this function ON when receiving weak signals.
➥ Push [P.AMP] to toggle between preamp-1 and
preamp-2 or turn the preamp OFF.

■ Attenuator

The attenuator prevents desired signals from
distorting when very strong signals are near the
desired frequency or when very strong electric fields,
such as from broadcasting stations, are near your
location.
➥ Push [ATT] toggle the 20 dB attenuator function
ON and OFF.
• "ATT" appears when the attenuator is turned ON.

■ AGC time constant

The AGC (Automatic Gain Control) controls receiver
gain to produce a constant audio output level even
when the received signal strength is varied by fading,
etc. Use AGC slow for normal phone operation; AGC
fast for receiving data and searching for signals.
➥ Push [AGC] momentary to toggle the AGC time
constant between fast and slow.
• "F.AGC" appears when the fast time constant is
selected.
• "AGC" appears when the slow time constant is
selected.
➥ Push [AGC] for 2 sec. to turn the AGC circuit OFF.
• "AGC OFF" appears when the AGC circuit is turned
OFF.
• Push [AGC] to turn the AGC circuit ON.
• S-meter is deactivated when the AGC circuit is turned
OFF.

■ Antenna selection

2 types of antenna can be connected to this receiver.
When 2 antennas are connected, select an antenna
depending on the operating condition.
➥ Push [ANT
(SET)
antenna 1 and 2 connectors.
• If a blank memory channel has been selected, push
[V/M] to select VFO mode in advance.
16
] for 2 sec. to toggle between the
USB
PREAMP 1 ANT 1 AGC BLANK BLANK
S1 3 5 7 9 20 40 60dB
VFO
"PREAMP" appears while the
preamp is activated.
USB
ATT ANT 1 AGC
BLANK BLANK
S1 3 5 7 9 20 40 60dB
V F O
"ATT" appears while the attenuator
is activated.
USB
R X
ANT 1 F. AGC AGC
BLANK BLANK
S1 3 5 7 9 20 40 60dB
VFO
"F.AGC" appears when the fast time
constant is selected.
USB
ANT 1 AGC BLANK BLANK
S1 3 5 7 9 20 40 60dB
VFO
"ANT1" appears when the
[ANT1] connector is in use.
R X
R X
R X