Scanner Filters

PAR Electronics, Inc. manufactures a broad line of scanner filters. Each can be custom tuned to desired notch frequencies and can come configured with a number of different connectors and genders.

The SYM series of filters are a 3 stage symmetrical design that achieves very fast recovery from the notch. Typical -3dB points are +/- 1.5% of the notched frequency- or about +/- 2.25MHz with a 150MHz notch. Typical notch depth is -35dB.

The UHF filters feature a -3dB bandwidth of under +/- 1% of center frequency.

Passband is DC to 1GHz in all cases.

Standard connectors are gold/Teflon Male/Female BNC, allowing easy cascading where more than one filter is required. See specifications for other connector types

The VHF-FM filter is a classical 3 pole filter designed to substantially reduce signals from the FM broadcast band by a minimum of –25 dB and a maximum of –50dB. Loss at 116 MHz is only –3dB, dropping rapidly from there to only -1.7 dB at 120 MHz.

In the SYM series, custom notch frequencies from 50MHz to 900 MHz are available at a small additional charge. Model number would be VHFSYM(XYZ)HT where XYZ= Notch Frequency in MHz for filters from 50MHz to 300MHz and UHFSYM(XYZ)HT for 300MHz and up.

The SYM5 series are triple notch filters designed to effectively attenuate a range of frequencies. Shown is the Channel 10 TV filter. The graph has markers set at the low, mid, and high frequencies of the U.S. CH10 television channel. Similar filters can be designed for say, attenuating the amateur 2M band (144-148 MHz). Passband is DC to 1GHz for all channels except CH2-5, where the passband is to 500MHz.

See EHAM reviews of the scanner filters.

Read the FAQ about scanner intermod.

VHFSYM152HT
VHFSYM158HT
VHFSYM162HT

UHFSYM454HT
UHFSYM462HT

VHF-FM

VHFSYM5(CH10TV)HT UHFSYM5(CH21TV)HT
VHFSYM5(CH08TV)HT