BPF 3/4 Helical band-pass filter

112-136MHz

Band Pass Filters BPF 3/4

Band-Pass Filter for the 112 - 136 MHz Band.

The BPF 3/4 is a 4-helical resonator band-pass filter with aperture-coupling between the resonators.

This filter can be used as a preselector to protect a receiver against interference from transmissions out of the passband, or it can be used to reduce spurious output from a transmitter with up to 50 W output power.

The filter can be tuned within the entire 112 - 136 MHz band. It has very small dimensions owing to the use of helical resonators. Careful design and choice of materials ensure reliable operation over a wide temperature range.

The housing is made of extruded aluminium, the chassis of steel, and teflon insulation has been used in the coaxial cables and in the connectors.

The filter is coated with black vinyl to prevent corrosion.