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Switchable RF Filter Board



I have designed a Low Pass RF Filter board for use with my new MEPT. Three frequency bands are selectable using standard 5Vdc logic control signals, typically from an Arduino.

The three frequency bands are:-

7MHz - 10MHz ham bands
14MHz - 18MHz ham bands
21MHz - 24MHz - 28MHz ham band

On the board is also a spare relay providing switching between a pair of normally open and closed contacts, this is useful for RF path switching.

The PCB is 100mm x 100mm in size and uses high voltage SMD capacitors and 0.63mm wire wound Toroids. There are also SMD components filtering the 5Vdc line to the ULN2003 control chip and relays.

Power rating of the filters is 100W.

Here are is a pictures of the filter board.