Speech Compressor; Preamp - Icom IC-756PROII Instruction Manual

Speech compressor

The RF speech compressor increases average RF
output power, improving signal strength and readabil-
ity in SSB.
• Speech compressor
q Select USB or LSB mode.
w Push [COMP] momentarily to turn the speech
compressor ON and OFF.
e Push [COMP] for 1 sec. to toggle between narrow,
middle or wide transmit filter.
• Transmit filter width:
NAR 2.0 kHz
MID 2.6 kHz
WIDE 2.9 kHz
• Compression level setting
q Select USB or LSB mode.
w Preset the transceiver as follows:
[COMP] function
[METER] function
[MIC GAIN] control
[COMP] control
[RF POWER] control : Max. counterclockwise
e Transmit at your normal voice level.
r Adjust the [MIC GAIN] control so that the ALC
meter reads within the ALC zone, whether or not
you speak softly or loudly.
t Push [COMP] momentarily to turn the speech
compressor ON.

Preamp

The preamp amplifies received signals in the front
end circuit to improve the S/N ratio and sensitivity.
The transceiver has 2 preamp types.
Push [P.AMP] to select one of 2 receive RF pre-
amps or to bypass them.
• "P. AMP1" activates 10 dB preamp for HF all bands.
• "P. AMP2" activates 16 dB high-gain preamp for
24 MHz band and above.
[P.AMP] switch
: OFF
: ALC
: Center position
: Center position
RECEIVE AND TRANSMIT
y Push [METER] once to select the COMP meter.
u Adjust the [COMP] control so that the COMP
meter reads within 10 dB and 20 dB.
5
1
25 50
10
0
S
2
Po
1.5
1
10
SWR 0
COMP
ALC
When the ALC meter peaks above the ALC zone,
your transmitted voice may be distorted.
[METER] switch
[MIC GAIN] control
[RF POWER] control
Regarding the use of the "P.AMP 2"
(Pre-amplifier 2)
The "P.AMP 2" is a high gain receive amplifier. When
the "P.AMP 2" is used during times of strong electric
fields, distortion sometimes results. In such cases,
use the transceiver with the "P.AMP 1" or "P.AMP
OFF" setting.
The "P.AMP 2" is most effective when:
• Used on bands above 24 MHz and when electric
fields are weak.
• Receive sensitivity is insufficient during low gain, or
while using a narrow band antenna (such as small
loop, a Beverage antenna or a shorten Yagi an-
tenna, etc.) is used.
COMP meter
9
+ 20
+ 40
+ 60dB
100
3
20
dB
[COMP] switch
[COMP] control
5
37