Icom IC-9100 Instruction Manual - Page 80

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. • N o indicator is displayed when the preamp is OFF. P. AMP P. AMP Wide dynamic range preamplifier. It is most effective for the 1.8 to 21 MHz bands. 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. • N o 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•ATT] ✔ 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 A G-1200 has been discontinued, but it can be still be used. *2 The optional UX-9100 is required for 1200 MHz frequency band operation. [P.AMP•ATT] About the Preamplifier and Attenuator switching procedure The Preamplifier and Attenuator are switched with [P.AMP/ATT], as shown below. • HF/50 MHz frequency bands P.AMP OFF P.AMP Push P.AMP Hold down Push ATT ON • 144/430/1200 MHz frequency bands P.AMP OFF P.AMP ON Hold down ATT ON Push Push 71