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SoftRock ver 9 Electronically Switched BPF

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  • tmasyl
    Greetings: I am new to SoftRock SDR and just recently received my version 9 kits from Tony. I sure am impressed with the packaging of the kits and the quality
    Message 1 of 2 , Jul 1 10:51 PM
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      Greetings:

      I am new to SoftRock SDR and just recently received my version 9 kits from Tony. I sure am impressed with the packaging of the kits and the quality of instructions! My goodness IMHO much better documentation than traditional kits - what a tremendous effort - thank you and congrats to everyone involved with this fine effort!!!

      I am presently studying the design of the electronically switched version I BP filter and I am curious about how this design evolved. I looked through the files section and didn't spot information on the filter impedance and measurements that may have been done on the FST3253 switches. It appears from the schematic the 50 Ohm antenna Z is stepped up to 200 Ohms and then stepped back down to 50 for feeding the receiver. I presume this was done to reduce the R-ON loss from the multiplexers. I tried to find RF performance information on the FST3253 with regards to crosstalk and isolation versus HF/VHF spectrum but couldn't find any coverage on that topic in the data sheet.

      It looks like much good work has gone into this BPF design and I imagine there may have been quite an extensive dialog at design time which I would like to read. Can anyone point me to the background information for this design?

      73 & Enjoy!
      Tom, VA7TA
    • Dave Brainerd
      ... I have some measurements on my bpf page at . My bpf board has 6 filters and 2 open positions. The loss measurements on
      Message 2 of 2 , Jul 1 11:29 PM
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        tmasyl wrote:
        > Greetings:
        >
        > I am new to SoftRock SDR and just recently received my version 9 kits from Tony. I sure am impressed with the packaging of the kits and the quality of instructions! My goodness IMHO much better documentation than traditional kits - what a tremendous effort - thank you and congrats to everyone involved with this fine effort!!!
        >
        > I am presently studying the design of the electronically switched version I BP filter and I am curious about how this design evolved. I looked through the files section and didn't spot information on the filter impedance and measurements that may have been done on the FST3253 switches. It appears from the schematic the 50 Ohm antenna Z is stepped up to 200 Ohms and then stepped back down to 50 for feeding the receiver. I presume this was done to reduce the R-ON loss from the multiplexers. I tried to find RF performance information on the FST3253 with regards to crosstalk and isolation versus HF/VHF spectrum but couldn't find any coverage on that topic in the data sheet.
        >
        > It looks like much good work has gone into this BPF design and I imagine there may have been quite an extensive dialog at design time which I would like to read. Can anyone point me to the background information for this design?
        >
        > 73 & Enjoy!
        > Tom, VA7TA
        >
        >
        >
        >
        >
        >
        >
        I have some measurements on my bpf page at
        <http://www.wb6dhw.com/BPF.html>. My bpf board has 6 filters and 2 open
        positions. The loss measurements on these positions show the loss
        through the just the 2 switches.

        Dave - WB6DHW
        <http://wb6dhw.com>
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