Roofing Filters - Kenwood TS-890S In-Depth Manual

02 RECEPTION CIRCUIT

Roofing Filters

Four types of roofing filters are equipped as standard as narrowband filters of high IP characteristics implemented by the
full down-conversion method. In addition, to meet the needs for narrower band filters, optional filters are available (sold
separately) and supported by a mounting slot. The "Photograph of Roofing Filters" is shown below:
Fig. 4 Photograph of the Roofing Filters
The filters of the 15 kHz, 6 kHz, 2.7 kHz, and 500 Hz (270 Hz) bandwidth are mounted from the top in the photograph.
The filters of the 15 kHz and 6 kHz bandwidth are the 4-pole monolithic crystal filters (hereinafter referred to as MCF),
and the filter of the 2.7 kHz bandwidth is the 6-pole MCF. The filter of the 500 Hz bandwidth is structured as the ladder
type to suppress in-band insertion losses and to steeply shape the adjacent out-of-band attenuation characteristics. The
ladder filter of the 270 Hz bandwidth, which is the much narrower band, is also available as an optional filter. For each
ladder filter frequency response, the "Frequency Response of the 500 Hz Bandwidth" and "Frequency Response of the
270 Hz Bandwidth" are shown below:
Fig. 5 Frequency response of
Fig. 6 Frequency response of
the 500 Hz Bandwidth
the 270 Hz Bandwidth (Option)
The roofing filters for the receiver can be selected regardless of the operation mode.
In the RX Filter screen which appears on the display by pressing and holding the [IF FIL] key, switching to the roofing
filter corresponding to the passband width can be used for the reduction of the interference signal.
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