VHF Low Pass filter for DRA818V module
26 December 2020 at 16:48
Β It is best to use the DRA818V VHF voice transceiver module with a low pass filter.
Since I'm building a VHF/UHF transceiver using the 818V and 818U modules, the VHF low pass filter was missing from the build.
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This design was based from the one here and only some small values changes made , I placed adjustable cap's on the center elements (the 56pF), so used 10-60pF trimmer cap and used 32pF on the ends (10+22pF parallel).Β
Schematic:
Β After build did some measurement on the spectrum analyzer:
Final iteration of the trimmers:
Β Attenuation at 200Mhz:
Filter shape from 100 to 300Mhz without normalization:
...now I need to finish the remaining of the transceiver..
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Have a great day!