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FM radio on 15 MHz?

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  • Günter Lorenz
    Hi, Is there any maths for Perseus which would make my local 95.0 MHz FM station appear on 15 MHz? In FM mode with 50 kHz, approx -88 dbm. 95.0 MHz is 70db++
    Message 1 of 7 , May 10, 2009
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      Hi,

      Is there any maths for Perseus which would make my local 95.0 MHz FM station appear on 15 MHz?
      In FM mode with 50 kHz, approx -88 dbm. 95.0 MHz is 70db++ on my FM tuner.
      The ALA1530+SSB is on the roof, sitting close to two FM antennas.

      73,
      Günter
      D-85354 Freising
      RX: Perseus ANT: ALA1530+SSB
    • Werner Karn
      theoretically the oszillator signal 80MHz could mix with the FM 95MHz and produce a 15 MHz signal ?? Werner ... theoretically the oszillator signal 80MHz
      Message 2 of 7 , May 10, 2009
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        theoretically the oszillator signal 80MHz could mix with the FM 95MHz and produce a 15 MHz signal ??   Werner

        Am 10. Mai 2009 22:43 schrieb Günter Lorenz <glorenz@...>:


        Hi,

        Is there any maths for Perseus which would make my local 95.0 MHz FM station appear on 15 MHz?
        In FM mode with 50 kHz, approx -88 dbm. 95.0 MHz is 70db++ on my FM tuner.
        The ALA1530+SSB is on the roof, sitting close to two FM antennas.

        73,
        Günter
        D-85354 Freising
        RX: Perseus ANT: ALA1530+SSB


      • Günter Lorenz
        Werner, thank you. As the 80 MHz will not leave the Perseus box, it must be the 95 MHz entering the circuitry at a very high level - can t measure, because my
        Message 3 of 7 , May 10, 2009
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          Werner, thank you. As the 80 MHz will not leave the Perseus box, it must be the 95 MHz entering the circuitry at a very high level - can't measure, because my Perseus stops at 40 MHz ;-)
          I'll do some tests with another antenna.
           
          73,
          Günter


          Von: perseus_SDR@yahoogroups.com [mailto:perseus_SDR@yahoogroups.com] Im Auftrag von Werner Karn
          Gesendet: Sonntag, 10. Mai 2009 23:03
          An: perseus_SDR@yahoogroups.com
          Betreff: Re: [perseus_SDR] FM radio on 15 MHz?

          theoretically the oszillator signal 80MHz could mix with the FM 95MHz and produce a 15 MHz signal ??   Werner

          Am 10. Mai 2009 22:43 schrieb Günter Lorenz <glorenz@...>:


          Hi,

          Is there any maths for Perseus which would make my local 95.0 MHz FM station appear on 15 MHz?
          In FM mode with 50 kHz, approx -88 dbm. 95.0 MHz is 70db++ on my FM tuner.
          The ALA1530+SSB is on the roof, sitting close to two FM antennas.

          73,
          Günter
          D-85354 Freising
          RX: Perseus ANT: ALA1530+SSB


        • dl4raj
          Signals are mirrored around 40MHz as center and around zero MHz as center. A signal on 80MHz would have a mirror at zero. A 95MHz signal therefore at -15MHz
          Message 4 of 7 , May 10, 2009
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            Signals are mirrored around 40MHz as center and around
            zero MHz as center.
            A signal on 80MHz would have a mirror at zero.
            A 95MHz signal therefore at '-15MHz' and 15MHz.
            I guess you have bypassed your preselector in Perseus .
            I've fed a -10dBm signal on 95MHz into Perseus.
            Nothing to hear on 15MHz with pres. on but a nice signal with
            pres. off.
            Even a 0dBm signal gives only a very weak audible mirror signal
            on 15MHz with pres. on.

            73
            Clemens
            DL4RAJ


            --- In perseus_SDR@yahoogroups.com, Günter Lorenz <glorenz@...> wrote:
            >
            > Hi,
            >
            > Is there any maths for Perseus which would make my local 95.0 MHz FM station appear on 15 MHz?
            > In FM mode with 50 kHz, approx -88 dbm. 95.0 MHz is 70db++ on my FM tuner.
            > The ALA1530+SSB is on the roof, sitting close to two FM antennas.
            >
            > 73,
            > Günter
            > D-85354 Freising
            > RX: Perseus ANT: ALA1530+SSB
            >
          • Henry
            Gunter, Here s one speculative suggestion for you. I believe the ADC clock is at 80 MHz. Is this correct? 95 - 80 = 15 Henry.
            Message 5 of 7 , May 10, 2009
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              Gunter,

              Here's one speculative suggestion for you.

              I believe the ADC clock is at 80 MHz. Is this correct?

              95 - 80 = 15



              Henry.



              Günter Lorenz wrote:
              > Hi,
              >
              > Is there any maths for Perseus which would make my local 95.0 MHz FM station appear on 15 MHz?
              > In FM mode with 50 kHz, approx -88 dbm. 95.0 MHz is 70db++ on my FM tuner.
              > The ALA1530+SSB is on the roof, sitting close to two FM antennas.
              >
              > 73,
              > Günter
              > D-85354 Freising
              > RX: Perseus ANT: ALA1530+SSB
              >
              >
              > ------------------------------------
              >
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            • Henry
              My apologies - I have just seen reading thru my other emails that others have already responded.
              Message 6 of 7 , May 10, 2009
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                My apologies - I have just seen reading thru my other emails that others
                have already responded.


                Henry wrote:
                > Gunter,
                >
                > Here's one speculative suggestion for you.
                >
                > I believe the ADC clock is at 80 MHz. Is this correct?
                >
                > 95 - 80 = 15
                >
                >
                >
                > Henry.
                >
                >
                >
                > Günter Lorenz wrote:
                >
                >> Hi,
                >>
                >> Is there any maths for Perseus which would make my local 95.0 MHz FM station appear on 15 MHz?
                >> In FM mode with 50 kHz, approx -88 dbm. 95.0 MHz is 70db++ on my FM tuner.
                >> The ALA1530+SSB is on the roof, sitting close to two FM antennas.
                >>
                >> 73,
                >> Günter
                >> D-85354 Freising
                >> RX: Perseus ANT: ALA1530+SSB
                >>
                >>
                >> ------------------------------------
                >>
                >> Yahoo! Groups Links
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                > ------------------------------------
                >
                > Yahoo! Groups Links
                >
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              • Günter Lorenz
                ... Yes, indeed! I don t even know why, perhaps because normally I do not note much difference, but in this case - yes, 15 MHz is clean again with Presel on.
                Message 7 of 7 , May 12, 2009
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                  > I guess you have bypassed your preselector in Perseus .

                  Yes, indeed! I don't even know why, perhaps because normally I do not note much difference, but in this case - yes, 15 MHz is "clean" again with Presel on.
                  Thanks to all who replied, and happy Perseusing!

                  73,
                  Günter
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