G4ZTR.co.uk
G4ZTR.co.uk

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70cms updated Feb '15

 

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2m Low Pass Filter

A recent purchase at G4ZTR was a 2m low
pass filter kit from W6PQL. I recently got around to building this and putting
it in a box. It’s a very easy kit to build with just a few large capacitors and
inductors. Parts are also supplied for a directional coupler, but I’ve left
these out for the time being.

 

The circuit board is multi-purpose, in that
for a 70cms low pass filter, the capacitance between large “pads” of the board
and the earth plane is all that is required. For 2m, capacitors are added to
provide the correct value.

 

A quick check on the network analyser shows
that the filter is performing as planned, with 0.1dB through loss on 2m, and
around 60dB attenuation on the third harmonic. This should be very useful in
multiband operations.