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2018-12-26

LOW-PASS FILTER FOR 2 TONES GENERATOR

Here is a 2 tones RF generator for 7030 and 7050 kHz, sold by funkamateur.de :





 

As harmonics are present at the output, a low-pass filter is required.
 
Good harmonics filters for amateur radio bands can be found at the G-QRP web site, good up to 10 Watts and low insertion loss :



The PCB filter fits in a 80 x 25 x 25 mm enclosure sold by SV1AFN 



The filter with 3 x T37-6



The result after tweaking the inductors :



Return loss @ 7050 kHz is 22 dB, SWR = 1.17





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