The AOR ABF128 is a receive bandpass filter especially designed for serious VHF airband listeners. This filter improves the strong signal handling characteristics of scanners and wideband receivers for VHF commercial Airband listening. The ABF128 is suitable for connection to most scanners and wideband receivers on the market, regardless of brand. The addition of this filter to the antenna's signal path provides additional selectivity which enables the receiver's circuitry to better cope with strong interfering signals that can leak into the 108-136 MHz VHF air band.
The ABF128 provides additional selectivity to any receiver's front end by reducing a multitude of unwanted strong signals from reaching and saturating the receiver's first mixer stage. This results is less interference and improved reception. The ABF125 offers excellent out-of-band attenuation typically of 25 dB from 0.3 to 75 MHz and 20 dB from 190 to 400 MHz. This makes the ABF128 suitable for connection to both external antennas and for connection directly under the whip aerial of a hand-held receiver. A BNC socket (female) is fitted to the top of the ABF128 and a BNC plug (male) to the other making connection to an aerial easy and straight forward.
The ABF128 is not an amplifier so will not boost signals, however the additional selectivity offered can significantly improve reception in many situations by removing unwanted strong signals which may overload the receiver and reduce it's effectiveness. When any connection is fitted to the aerial signal path some reduction of signal is resulted (attenuation) however the ABF128 in band attenuation level is very small due to the excellent in band V.S.W.R. of 2:1 resulting in a loss of only about 4 dB.
Note: Remember to remove the ABF128 from the antenna input when monitoring signals other than VHF Airband or signal strength will be dramatically reduced.
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