Preamplifier; Attenuator - Icom IC-7800 Instruction Manual

5
FUNCTIONS FOR RECEIVE

■ Preamplifier

[P.AMP]
NOTE:
The preamp (P.AMP1 or P.AMP2) cannot be used
while the digital selector is activated.
Also the preamp is automatically disabled when the
digital selector is turned ON.

■ Attenuator

[ATT]
The preamp amplifies received signals in the receiver
front end, to improve the S/N ratio and sensitivity. Set
this to preamp 1 or preamp 2 when receiving weak
signals.
➥ Push [P.AMP] several times to set the preamp OFF,
preamp 1 ON or preamp 2 ON.
For all HF bands
High-gain preamp for 24 MHz band and
above (Available for all HF and 50 MHz
bands)
✔ About the "P.AMP2"
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 short Yagi antenna).
The attenuator prevents a desired signal from distor-
tion when very strong signals are near the desired fre-
quency or when very strong electric fields, such as
from broadcasting stations, are near your location.
➥ Push [ATT] several times to set the attenuator 6 dB,
12 dB, 18 dB or attenuator OFF.
➥ Hold down [ATT] for 1 second several times to set
the attenuator 3 dB, 6 dB, 9 dB, 12 dB, 15 dB, 18
dB, 21 dB or attenuator OFF.
3 dB
attenuation
6 dB
attenuation
9 dB
attenuation
12 dB
attenuation
5-10
15 dB
attenuation
18 dB
attenuation
21 dB
attenuation