71
5
FUNCTIONS FOR RECEIVE
■
Preamplifier
The preamplifier amplifies weak signals in the receiver
front end, to improve the S/N ratio and sensitivity.
Turn this function ON when receiving weak signals.
The AG-25, AG-35 or AG-1200*
1
preamplifier unit is
required for 144, 430 or 1200 MHz*
2
frequency band.
• Be sure to set the “EXT-P.AMP” item for each frequency
band in the Set mode. (pp. 165, 166)
(Frequency band: HF/50 MHz)
➥
Push [P.AMP•ATT] one or more times to set the pre
-
amp OFF, preamp 1 ON or preamp 2 ON.
• Either “P. AMP
” or “P. AMP ” is displayed when the
preamp 1 or preamp 2 is ON.
• No indicator is displayed when the preamp is OFF.
P. AMP
Wide dynamic range preamplifier. It is most
effective for the 1.8 to 21 MHz bands.
P. AMP
High-gain preamplifier. It is most effective
for the 24 to 50 MHz bands.
(Frequency band: 144/430/1200 MHz
*
2
)
➥
Push [P.AMP•ATT] once or twice to turn an optional
preamplifier unit ON or OFF, if installed.
• “P.AMP” appears when the preamplifier unit is ON.
• No indicator is displayed when the preamplifier unit is
OFF.
■
Attenuator
The attenuator prevents a desired signal from being
distorted when very strong signals are near the signal’s
frequency, or when very strong electromagnetic fields,
such as from broadcast stations are near your location.
These can both be independently set for each band.
➥
Hold down [P.AMP/ATT] for 1 second to turn ON the
Attenuator.
• “ATT” appears on the display when the Attenuator is
ON.
➥
Push [P.AMP/ATT] momentarily to turn it OFF.
[P
.AMP•A
TT]
✔
About the “P.AMP2” preamplifier
The preamp 2 is a high gain receive amplifier. When
it is used in the presence of strong electromagnetic
fields, distortion sometimes results. In such cases, use
either the “P.AMP 1” or “P.AMP OFF” setting.
Preamp 2 is most effective when:
• Used on bands above 24 MHz and when signals are
weak.
• Receive sensitivity is insufficient when using low-gain
antennas, or while using a narrow band antenna.
(such as small loop, a Beverage antenna or a short
Yagi antenna)
*
1
AG-1200 has been discontinued, but it can be still be
used.
*
2
The optional UX-9100 is required for 1200 MHz frequency
band operation.
About the Preamplifier and Attenuator switching procedure
The Preamplifier and Attenuator are switched with [P.AMP/ATT], as shown below.
Hold down
Push
ATT ON
Push
P.AMP
OFF
P.AMP
ON
Push
ATT ON
Hold down
Push
P.AMP
OFF
P.AMP
P.AMP
• HF/50 MHz frequency bands
• 144/430/1200 MHz frequency bands
[P
.AMP•A
TT]
