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Lab news, 450'ish khz softrock v6.1 results...

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  • Mike
    Hi, Ive just finished building a softrock v6.1 board with the components (band pass filter) for around 460khz. (Using the 1.843mhz xtal ==460khz ish) from
    Message 1 of 2 , Sep 1, 2006
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      Hi,
      Ive just finished building a softrock v6.1 board with the components
      (band pass filter) for around 460khz. (Using the 1.843mhz xtal
      ==460khz'ish) from quick testing it seems extremely sensitive.

      One problem was trying to wind 118turns onto a T30-2 core - I got as
      far as 86 Turns and switched to "that'll do mode" :) - Tony had advised
      me this was nigh impossible and has kindly sent some T50-1 cores, which
      will be wound when they arrive.

      Around 450khz it will easily detect RF fed via a signal generator at
      -127dbm (making a switchable attenuator is on my to-do list..)

      At 220 Khz (/8 and who's IF is there anyhow?) -81dbm seems the lowest.

      At 2nd Harmonic "up" 910khz (not spot on but withing the range) a
      signal at least -50dbm needs to be present before it starts to show
      in the 460khz region (e.g 2nd harmonic)

      Hooking up the signal generator to the crystal at at -7dbm output level,
      its possible to tune the V6.1 (in 455Khz "kit" mode) from

      320Khz to 16Mhz when JP1 is at /8 = Thats External Osc, which
      corresponds to a frequency range of 40khz to 2Mhz. (to be verified
      with another signal generator, I suspect > 100khz is the usable range)

      Im pretty sure I saw some standard time transmission around 60khz,
      does anyone have a spectral plot of such transmissions ?

      -----------

      I was originally going to modify an Icom IC1500 and tap the 455Khz IF
      from the underside of the main pcb, however my soldering iron which has
      a narrow tip looked like a tree trunk next to the components. Since the
      "do I really want to risk trashing mr dc to light for a softrock
      expeirment" reality check kicked in, Ive decided to switch to plan B
      taking the 455khz (or 450?) IF from an AOR 2002 dinosaur this is Pending..

      73 Mike,
      OH2FCZ.
    • Cecil Bayona
      ... For 455KHz or 10.7MHz and actually several in-between I.F. s you can use very inexpensive commercial I.F. cans that can be bought for a fraction of a
      Message 2 of 2 , Sep 1, 2006
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        Mike wrote:
        > Hi,
        > Ive just finished building a softrock v6.1 board with the components
        > (band pass filter) for around 460khz. (Using the 1.843mhz xtal
        > ==460khz'ish) from quick testing it seems extremely sensitive.
        >
        > One problem was trying to wind 118turns onto a T30-2 core - I got as
        > far as 86 Turns and switched to "that'll do mode" :) - Tony had advised
        > me this was nigh impossible and has kindly sent some T50-1 cores, which
        > will be wound when they arrive.
        >
        > Around 450khz it will easily detect RF fed via a signal generator at
        > -127dbm (making a switchable attenuator is on my to-do list..)
        >
        > At 220 Khz (/8 and who's IF is there anyhow?) -81dbm seems the lowest.
        >
        > At 2nd Harmonic "up" 910khz (not spot on but withing the range) a
        > signal at least -50dbm needs to be present before it starts to show
        > in the 460khz region (e.g 2nd harmonic)
        >
        > Hooking up the signal generator to the crystal at at -7dbm output level,
        > its possible to tune the V6.1 (in 455Khz "kit" mode) from
        >
        > 320Khz to 16Mhz when JP1 is at /8 = Thats External Osc, which
        > corresponds to a frequency range of 40khz to 2Mhz. (to be verified
        > with another signal generator, I suspect > 100khz is the usable range)
        >
        > Im pretty sure I saw some standard time transmission around 60khz,
        > does anyone have a spectral plot of such transmissions ?
        >
        > -----------
        >
        > I was originally going to modify an Icom IC1500 and tap the 455Khz IF
        > from the underside of the main pcb, however my soldering iron which has
        > a narrow tip looked like a tree trunk next to the components. Since the
        > "do I really want to risk trashing mr dc to light for a softrock
        > expeirment" reality check kicked in, Ive decided to switch to plan B
        > taking the 455khz (or 450?) IF from an AOR 2002 dinosaur this is Pending..
        >
        > 73 Mike,
        > OH2FCZ.
        >
        >
        >
        >
        > Yahoo! Groups Links
        >
        >
        >
        >
        >
        >
        >
        For 455KHz or 10.7MHz and actually several in-between I.F.'s you can use
        very inexpensive commercial I.F. cans that can be bought for a
        fraction of a dollar.

        Also there is no need for 118 turns when using cores, at that low a
        frequency type 2 cores is the wrong type to use, a more practical core
        would be type FT37-43 Ferrite core were you would only need a small
        fraction of those turns. For use at frequencies lower down a FT37-77
        core could be quite useful.

        For experimenting with Softrocks these items can be found at a
        reasonable size Hamfest if one does not want to incur minimum order
        sizes. Some outfits offer core samplers at a low price that might have
        several different type of cores in one package.
        --

        Cecil
        KD5NWA
        www.qrpradio.com www.hpsdr.com

        "Sacred Cows make the best Hamburger!" Don Seglio Batuna
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