Preselector/Bandpass filter for GMRS repeaters

SKU: PRESELECTOR-FILTER
$180.00
$180.00
Unavailable
per item

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A typical flatpack duplexer will notch out the TX frequency from reaching the RX radio in a repeater configuration, but does not filter out noise on any other frequencies such as adjacent bands 70cm amateur repeaters commercial LMR. This preselector bandpass filter is tuned for the GMRS repeater input frequencies to only allow a small slice of bandwidth to reach the RX radio and drastically attenuate everything else.


Unwanted out of band signals can overload the RX radio's frontend and/or desensitize the RX radio's receiver. Placing this filter between the duplexer and RX radio will significantly attenuate unwanted signals while complementing the duplexer's TX isolation to provide more comprehensive front-end protection. The end result is a repeater capable of higher sensitivity especially in noisy environments.


Do not use this between a duplexer and antenna or it will block the TX radio from transmitting. Do not use this for simplex (462.x) applications without retuning first.


Passband: 467.6375+-1.5MHz

Max power: 50W

Insertion loss: 1.5dB or less

Rejection: >35dB@+- 10MHz

VSWR: 1.3 or less

Connector: N-F

Weight: 1KG

Dimensions: 175x125x25mm (not including the connectors)


More info below

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While there is some insertion loss for desired signals (1.5dB or less), there is much more attenuation for signals outside of the passband.  Even the GMRS repeater output and simplex frequencies are attenuated by around 15dB (complementing the duplexer notch).  The closest frequency in the 70cm Amateur band is attenuated by over 50dB.  Many LMR (licensed commercial) frequencies are drastically attenuated as well.
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