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Check out this Dead Bug Style Bandpass Filter design by PA1ED. If you want great noise isolation a metal box is ideal, check out his FR4 box design! Great idea using FR4 for the PCBs and for the case.
 “Because I don`t have a spectrum analyzer,I was not able to test it if the Bandpass filter was doing a good job on the frequency it was designed for.So I took out the earlier filter and put the new filter in my Bitx 20 V3.After I made the connections,I put the power and a antenna on the Bitx.And guess what.I didn`t hear anything,only noise.After a turn on one of the 20pf variable capacitors the stations where comming thru.I searched for a weak station and began to turn the three variable caps so that the incoming station was on his best.”
Via: Dangerous Prototypes and Soldersmoke
