HPN-30118 Combined Notch Filter:
useable frequency range: 31 - 80 and 118 - 1600 MHz
insertion loss: 1 dB typ
suppression in the range: 0 - 20 MHz: 30 dB min
suppression in the range: 87 - 109 MHz: 30 dB min
no intermodulation - passive filter
input connector: BNC/f
output connector: BNC/m
input/output impedance: 50 Ohms
size: 18,5 x 34 x 70 mm
weight: 35 g

This filter is primarily designed for use between the antenna and a receiver/scanner, although it can find its use in many other applications. It combines a passive high pass filter that greatly attenuates all signals below 30 MHz and a passive notch filter that suppresses the strong signals from the VHF FM broadcast band by at least 30dB.

It passes all signals from 31 to 80 MHz and from 118 to 1600 MHz with a negligeable insertion loss below 1dB. Hence it is an ideal accessory for all hand held and table top scanners (Yupiteru, Alinco, AOR, ICOM, YAESU, Uniden-Bearcat etc.). Its BNC coax connectors simply fit onto the antenna input connector and the antenna is connected to the BNC connector of the filter.

The filter finds its use at places with strong broadcast signals from LW, MW and SW bands and especially from VHF FM band. These signals very often cause overloading of the receiver front end and hence significant deterioration of sensitivity. With the filter it is then not necessary to use the attenuator of the receiver to get rid of the interference and overloading, so the receiver sensitivity is maintained. The filter eliminates all the interference from all the bands below 30 MHz, including CB. This filter also improves reception in the air-band which is close to the VHF FM band. The filter has been tested at places close to 100kW broadcast transmitters when even top class scanners like ICOM IC-R8500 or AOR AR-5000 suffer from overloading in the air-band. The filter enables clear reception at such difficult locations.

It may reduce image reception of signals from VHF FM band. It can also be used between a wide band antenna, such as discone, vertical or log-periodic, and a pre-amplifier, which will reduce the overloading of the wide band preamp.