SP9BSL
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alter Hase
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The HF filter board
« on: 30. June 2020, 09:48:29 »
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Hi,
the filter board is built in the fasion of some commercial rigs, each band was designed as a LPF and HPF in series, the HPF is used only for receive path. LPF filter is Cauer type (Elliptical) and HPF is "ordinary" Buterworth one. It is designed to filter the bands: 160m, 80m, 60&40m, 30&20m, 17&15m, 12&10m, 6m and aditionally only LPF for up to 6m. The last capability is designed to work with several receivers at different bands - we'll se if this is usable 
The board has built-in 12dB LNA (we work at the final value of amplification) flat response for all the supported bands.
The bands are switched by I2C expander which is defined in SParkle hardware definition of UHSDR.
Board contains also the SWR/Power measurement circuit and some other circuits to perform VNA functionality for ATU (future expansion).
Presented revision has very stuid mistake with the relays flipped. To be changed in new revision...
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SParkle_HF_Filter_board_measurements.pdf
