The ABF128 is a receive (only) bandpass filter
especially designed to improve strong signal handling characteristics of
receivers for VHF commercial Airband listening. The AFB128 is suitable not
only for AOR receivers, but also for most airband and wideband receivers on
the market. The addition of ABF128 will provide additional selectivity, and
allow the receiver's circuitry to cope much more easily with strong
interfering signals such as Band-2 Stereo or Shortwave broadcast
transmissions, which can be manifest in many ways such as "hissing",
multi-signal hash and desensitization of the receiver.
The ABF128 will provide additional selectivity (in many
situations) to any receiver's "front end" by reducing the multitude of
unwanted strong signals from reaching and saturating the receiver's first
mixer stage. This results in less interference and improved reception.
This makes the ABF128 suitable for connection to both
external antennas and right under the whip antenna of a handheld receiver.
The ABF128 is not an amplifier and 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. Band attenuation is very
small, due to the excellent in band V.S.W.R. of 2;1 resulting in a loss of
only about 4dB.
NOTE: Since this is a
blocking filter, it must be removed for normal reception outside the air band.
Alternatively, a second antenna selectable by a common A/B
TV antenna switch may be installed, or a single antenna may be fed to a common
A/B TV antenna switch, one side connected to the filter which is connected to
a TV splitter/combiner, and the other to to the second port on the splitter,
the output of which is connected to the scanner.
