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Re: FT1000 MK5 Field / Icom radio IF panadapter.

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  • Lyle Koehler, K0LR
    On my original IC-706, I was able to tap into the circuit at the input to the 9 MHz filter. Since it appears to be a fairly low-impedance point, I simply
    Message 1 of 9 , Jun 1, 2006
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      On my original IC-706, I was able to tap into the circuit at the input
      to the 9 MHz filter. Since it appears to be a fairly low-impedance
      point, I simply coupled the signal through a 50 pF capacitor and
      brought out a short piece of RG-174 coax with an inline RCA phono
      connector. There is a ceramic roofing filter in the first IF at 69
      MHz. The service manual doesn't provide any information on the
      bandwidth, but it appears to be about 25 kHz. With my homebrew general-
      coverage SDR receiver set so that the center frequency comes out at 12
      kHz, the panadapter provides a +/- 12 kHz display. I noticed that with
      a fixed signal coming in, the output frequency jumps around depending
      on what mode you're using. Not a surprise, but it probably screws up
      the centering of the panadapter display if you want to use it in
      multiple modes.

      The output level on the 706 IF is not excessive; if anything, it could
      use a little more gain going into the SD receiver.

      Lyle, K0LR
    • ccmarco2004
      Hi Lyle, good news because i also own a IC-706. some questions : - do you feed the SDR by mean of empty filter slot input line ? - or is the SDR input in
      Message 2 of 9 , Jun 1, 2006
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        Hi Lyle,
        good news because i also own a IC-706.

        some questions :

        - do you feed the SDR by mean of empty filter slot input line ?
        - or is the SDR input in parallel with the used filter ?
        - did you notice injected noise to 706 RXed signal when using SDR
        connection ?

        I have to take a look to 706 schematic to see if the radio disable
        the feeding of unselected IF filter slot.

        I was thinking to use a Jfet amplifier as buffer / decoupler,

        About th 25 KHz panning, they are not so much but better than
        nothing.

        Many Thanks, Marco.

        --- In softrock40@yahoogroups.com, "Lyle Koehler, K0LR" <k0lr@...>
        wrote:
        >
        > On my original IC-706, I was able to tap into the circuit at the
        input
        > to the 9 MHz filter. Since it appears to be a fairly low-impedance
        > point, I simply coupled the signal through a 50 pF capacitor and
        > brought out a short piece of RG-174 coax with an inline RCA phono
        > connector. There is a ceramic roofing filter in the first IF at 69
        > MHz. The service manual doesn't provide any information on the
        > bandwidth, but it appears to be about 25 kHz. With my homebrew
        general-
        > coverage SDR receiver set so that the center frequency comes out
        at 12
        > kHz, the panadapter provides a +/- 12 kHz display. I noticed that
        with
        > a fixed signal coming in, the output frequency jumps around
        depending
        > on what mode you're using. Not a surprise, but it probably screws
        up
        > the centering of the panadapter display if you want to use it in
        > multiple modes.
        >
        > The output level on the 706 IF is not excessive; if anything, it
        could
        > use a little more gain going into the SD receiver.
        >
        > Lyle, K0LR
        >
      • ccmarco2004
        Hi, i was just thinking to build a follower based on J310 Jfet to decouple the IF chain from the SDR input. Thanks for the Tip. Bye, Marco.
        Message 3 of 9 , Jun 1, 2006
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          Hi, i was just thinking to build a follower based on J310 Jfet to
          decouple the IF chain from the SDR input.

          Thanks for the Tip.

          Bye, Marco.

          --- In softrock40@yahoogroups.com, FRANCIS CARCIA <carcia@...> wrote:
          >
          >You might want to reduce the op amp gain when interfaced to a radio
          >with gain ahead of the modules. I put a 6 dB pad in place of the
          >input filter in my SDR module. my Racal had a low Z connection so it
          >was easy. you might get away with a high series resistor like 4.7K so
          >you don't load the radio. A FET amplifier set up as a source follower
          >would provide an interface that would not load down the radio also.
        • ccmarco2004
          Hi Gian, many thanks for detailed FT-1000 IF connection aid. I have just a question about v7.0 schematic : yesterday i was simulating the shifter network for
          Message 4 of 9 , Jun 1, 2006
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            Hi Gian,

            many thanks for detailed FT-1000 IF connection aid.

            I have just a question about v7.0 schematic :

            yesterday i was simulating the shifter network for 10 meter band
            version (R8: 1K, C9 : 10pF), and taking into account the comparator
            propagation delay, 4.2 nS, and input capacitance, 2 pF, i have
            obtained a total group delay greater than expected (8.86 nS, 90
            degree @ 28.204 MHz).

            I also thinked that could be very difficult trim & fix exactly this
            delay, due to parassitic parameter variance (thermal, aging, etc
            etc).

            From this aspect, is not much better the v6.0 configuration, with
            digital divider ?

            Am i wrong in some way ?

            Could you quickly explain me performance differences from SR v6.0
            and v7.0 ?

            Saluti, Marco.




            --- In softrock40@yahoogroups.com, "Giancarlo" <i7swx@...> wrote:
            >
            > --- In softrock40@yahoogroups.com, "ccmarco2004" <ccmarco@> wrote:
            > >
            > > Hi to all,
            > > i'm new of this group, i'm awaiting for two, just ordered,
            > SoftRock
            > > kit, one v6.0 and one v7.0.
            > >
            > > I was wondering if someone could give me any tip regarding the
            use
            > > of these circuits as IF panadapter for the FT-1000 MKV Field
            8.215
            > > MHz IF and Icom's 9.015 Mhz IF.
            > >
            > > My intent is to modify circuits input filters, shift network
            (for
            > > v7.0)and Xtals to obtain proper tuning on center IF freq.
            > >
            > > Maybe could be also good to use an IF input preamplifier to feed
            > > SoftRock input to avoid IF chains loading.
            > >
            > > For Yaesu seems fine to use 8.192 MHz Xtal with SR v7.0 as seems
            > > fine to use 9 MHz Xtal for Icom.
            > >
            > > I could be good also to use 36 MHz Xtal with SR v6.0 with 4x
            > setting.
            > >
            > > Has anyone already done something like that ?
            > >
            > > Thanks in advance.
            > >
            > > Marco, IW2NYX.
            > >
            >
            > Hi Marco,
            >
            > my comments to your question are only "suggestions" as I have not
            > tried anything.
            >
            > As you said you will have to change the xtal for the proper
            receiver
            > IF selected. For SR V7 you will need a xtal cut for the yaesu
            8.192
            > or icom 9.0+ IF; for this you will have to adjust the phasing
            > capacitor's value. For the SR V6 you will need a xtal IF x 4.
            >
            > I suggest you not to have any filter at the SR input.
            >
            > For the Yaesu FT1000MK you should attach the SR at the secondary
            of
            > T2001 in the Noise Blanker IF amplifier. If not enough output to
            > drive the SR you can attach it to T2002 secondary output.
            > I do not know what is the impedance at these points. While
            modifying
            > the nd Mixer and 2nd IF in the FT1000MP I "discovered" (measure
            > guessing) some transformers secondaries where around 200 ohm (???).
            >
            > To avoid mismatching problems, you should add a JFET buffer (J310
            or
            > BF245) with a 47 to 100 ohm R and a parallel C of 0.1uF R between
            > the source and the SR input primary transformer (one side of it to
            > gnd).
            >
            > With this solution you will monitor all signals passing througfht
            > the 70 MHz 1st IF roofing filter, although being at 8 MHz.
            >
            > Regarding ICOM transceivers I do not know which model you are
            > thinking of. The IC756, IC775 and IC765 are quite similar at the
            2nd
            > conversion. You may try to connect the SR, with input JFET buffer
            > connected at the 2nd IF roofing filter FL23. If not enough gain
            then
            > you may replace the JFET buffer with a DGM cascode amplifier or
            have
            > a grounded gate JFET ampolifier following the JFET buffer and
            > driving the SoftRock.
            >
            > These are ideas that may work right away ... please post any "try
            > and buy" you may experiment.
            >
            > For additional discussions in Italian you can send me direct mail.
            >
            > 73
            >
            > Gian
            > I7SWX
            >
          • Lyle Koehler, K0LR
            ... The SDR input is in parallel with the used filter. I offset the SDR local oscillator so that the center of the filter passband came out at 13 kHz on the
            Message 5 of 9 , Jun 1, 2006
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              --- In softrock40@yahoogroups.com, "ccmarco2004" <ccmarco@...> wrote:
              >
              > Hi Lyle,
              > good news because i also own a IC-706.
              >
              > some questions :
              >
              > - do you feed the SDR by mean of empty filter slot input line ?
              > - or is the SDR input in parallel with the used filter ?
              > - did you notice injected noise to 706 RXed signal when using SDR
              > connection ?
              >

              The SDR input is in parallel with the used filter. I offset the SDR
              local oscillator so that the center of the filter passband came out
              at 13 kHz on the Winrad display. That kept the local oscillator out
              of the passband, and I didn't notice any injected noise. But a FET
              follower is a good idea because it would reduce the loading of the
              IF circuit and would also provide some reverse isolation.

              Lyle, K0LR
            • Giancarlo
              Hi Marco, pse see below ... comparator ... OK. Going lower in frequency you will have a lower effect of group delay. ... this ... Nothing is perfect in this
              Message 6 of 9 , Jun 2, 2006
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                Hi Marco,

                pse see below

                --- In softrock40@yahoogroups.com, "ccmarco2004" <ccmarco@...> wrote:
                >
                > Hi Gian,
                >
                > many thanks for detailed FT-1000 IF connection aid.
                >
                > I have just a question about v7.0 schematic :
                >
                > yesterday i was simulating the shifter network for 10 meter band
                > version (R8: 1K, C9 : 10pF), and taking into account the
                comparator
                > propagation delay, 4.2 nS, and input capacitance, 2 pF, i have
                > obtained a total group delay greater than expected (8.86 nS, 90
                > degree @ 28.204 MHz).

                OK. Going lower in frequency you will have a lower effect of group
                delay.

                > I also thinked that could be very difficult trim & fix exactly
                this
                > delay, due to parassitic parameter variance (thermal, aging, etc
                > etc).

                Nothing is perfect in this world ... so you have to compromise ...
                and adapt yourself and the circuit...hi

                > From this aspect, is not much better the v6.0 configuration, with
                > digital divider ?

                Yes

                > Am i wrong in some way ?

                NO

                > Could you quickly explain me performance differences from SR v6.0
                > and v7.0 ?

                I havent done any measurements comparison between the two. The V6
                certainly has a better quadrature generation.

                I am working an a digital quadrature circuit where we have a divide
                by 2 that will make possible to reduce the L.O. frequency
                particularly going up to 28-30MHz band.

                I will keep the group posted ... last night I got a fault on the
                OPA ...one channel went bang !"!! hi

                Going out for lunch with XYL, family and friend to celebrate out
                37th wedding anniversary ...hi

                73

                Gian
                I7SWX
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