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RE: Warning !!! Re: [FT897] Cause Identified!!!: FM station "bleeds" across entire 88-108 band Warning !!!

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  • Mark Vaughan
    I agree with your risk here re the pin diodes. However I have been running an ATAS120 in HF on one side of the car, and an VHF/UHF Maldol on the other side. SO
    Message 1 of 27 , Oct 1, 2006
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      I agree with your risk here re the pin diodes.
      However I have been running an ATAS120 in HF on one side of the car, and an
      VHF/UHF Maldol on the other side.
      SO FAR SO GOOD !!
      I have experienced problems in the past running several radio's side by
      side, with large close HF antennas, and both radio's running the same freq.
      Things were OK up to 100W, but 400W caused damage.

      I know this is no definitive proof of anything, but a trend that is So Far
      so Good!

      73 Mark M0VAU

      _____

      From: FT897@yahoogroups.com [mailto:FT897@yahoogroups.com] On Behalf Of Dan
      Eisenman
      Sent: 30 September 2006 19:38
      To: FT897@yahoogroups.com
      Subject: Warning !!! Re: [FT897] Cause Identified!!!: FM station "bleeds"
      across entire 88-108 band Warning !!!



      Craig;
      Just a reminder - make sure you do not have two antennas on the FT-897
      that are tuned to the same frequency , the unit has pin diodes on the
      UHF antenna circuit
      , not an antenna relay.You could get RF coming in the UHF side and
      burning out the front end.
      This could happen even if the FT-897 was turned off.
      Example 2 40 meter antennas hooked to the FT-897 , you transmit on one
      dipole
      (HF side) the other (hooked to UHF) picks up the RF and feeds it into
      the UHF side and fries the front end.
      Just as a thought this could also happen when using another rig
      separate from the FT-897 and get the same result.
      The FT-897 would not even have to be on.
      73
      Dan
      K8ICB in Florida

      On Sep 30, 2006, at 12:48 PM, Craig Sharrow wrote:

      I want to thank all the folks that provided thoughts, suggestions, and
      troubleshooting tips.

      It helped me to be more structured in my diagnostic techniques, which
      helped identify the source of the problem.

      It's the antenna, stupid! Yup, I swapped the VHF antenna for the
      dipole, and suddenly the 88-108FM band cleaned up a bunch, and I was
      able to clearly pickup at least an additional 10 stations.
      Interestingly, above 101.3 things got a bit squirrely - and only 1 or
      2 stations (out of about a dozen that "should have been there") came
      in.

      Now the only problem is, if I want to listen to HF and FM and TX/RX on
      2m there's a little bit of a problem regarding having the correct
      antenna inputs. (BTW, I'm using the Diamond X-50A for VHF/UHF).

      [Non-text portions of this message have been removed]






      [Non-text portions of this message have been removed]
    • Charles Scott
      Mark: Good point. Some VHF/UHF mobile antennas can couple in quite a bit of HF energy and the opposite can also be true. One particularly problematic antenna
      Message 2 of 27 , Oct 1, 2006
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        Mark:
        Good point. Some VHF/UHF mobile antennas can couple in quite a bit of HF
        energy and the opposite can also be true. One particularly problematic
        antenna in this respect is a 2 Meter collinear, which can pick up a
        significant amount of power from an HF antenna somewhere else on the
        vehicle. (Of course collinear's are great mobile antennas for 2 meter
        mobile, so solving the problem is worth the effort.)
        There's a variety of ways to solve these problems. If you use a diplexer
        type of device to combine both HF and VHF/UHF onto a single transmission
        line, you don't have to worry about this since the filters in the diplexer
        will only deliver the energy to the proper port. Band-pass, low-pass, and
        high-pass filters can also prevent problems.
        A simple thing to do is to use a diplexer type of device with a small
        dummy load on the opposite port. For example, if you insert a diplexer
        with one HF port, one VHF/UHF port, and a common port so that the common
        port is connected to the VHF/UHF antenna, the VHF/UHF port is connected to
        the VHF/UHF connector on the radio, and the HF port is connected to a
        light dummy load, then any HF energy that enters the antenna will be
        directed to the dummy load and will not bother the radio.
        There's any number of other ways to deal with this problem, so there's
        no excuse for suffering damage to the opposite RF input on the radio
        unless you're just not aware that it can happen.
        (Note also that this is one of the causes of instability problems with
        the FT-100 Yaesu radios, so it's not just a matter of damaging an input
        device.)

        Chuck - N8DNX




        On Sun, 1 Oct 2006, Mark Vaughan wrote:

        > I agree with your risk here re the pin diodes.
        > However I have been running an ATAS120 in HF on one side of the car, and an
        > VHF/UHF Maldol on the other side.
        > SO FAR SO GOOD !!
        > I have experienced problems in the past running several radio's side by
        > side, with large close HF antennas, and both radio's running the same freq.
        > Things were OK up to 100W, but 400W caused damage.
        >
        > I know this is no definitive proof of anything, but a trend that is So Far
        > so Good!
        >
        > 73 Mark M0VAU
      • Mark Vaughan
        My issue though Charles was that whilst I would expect to get problems, I don t. I ve only had problems when I ve gone above 100W HF to another radio on HF, so
        Message 3 of 27 , Oct 1, 2006
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          My issue though Charles was that whilst I would expect to get problems, I
          don't.
          I've only had problems when I've gone above 100W HF to another radio on HF,
          so whilst the 897 and 857's have sensitive pin diodes on the inputs, Yaesu
          seem to have allowed for the feedback that is common in such cases without
          the need to dump anything with a diplexer or circulator.
          73 Mark M0VAU

          _____

          From: FT897@yahoogroups.com [mailto:FT897@yahoogroups.com] On Behalf Of
          Charles Scott
          Sent: 01 October 2006 18:39
          To: FT897@yahoogroups.com
          Subject: RE: Warning !!! Re: [FT897] Cause Identified!!!: FM station
          "bleeds" across entire 88-108 band Warning !!!




          Mark:
          Good point. Some VHF/UHF mobile antennas can couple in quite a bit of HF
          energy and the opposite can also be true. One particularly problematic
          antenna in this respect is a 2 Meter collinear, which can pick up a
          significant amount of power from an HF antenna somewhere else on the
          vehicle. (Of course collinear's are great mobile antennas for 2 meter
          mobile, so solving the problem is worth the effort.)
          There's a variety of ways to solve these problems. If you use a diplexer
          type of device to combine both HF and VHF/UHF onto a single transmission
          line, you don't have to worry about this since the filters in the diplexer
          will only deliver the energy to the proper port. Band-pass, low-pass, and
          high-pass filters can also prevent problems.
          A simple thing to do is to use a diplexer type of device with a small
          dummy load on the opposite port. For example, if you insert a diplexer
          with one HF port, one VHF/UHF port, and a common port so that the common
          port is connected to the VHF/UHF antenna, the VHF/UHF port is connected to
          the VHF/UHF connector on the radio, and the HF port is connected to a
          light dummy load, then any HF energy that enters the antenna will be
          directed to the dummy load and will not bother the radio.
          There's any number of other ways to deal with this problem, so there's
          no excuse for suffering damage to the opposite RF input on the radio
          unless you're just not aware that it can happen.
          (Note also that this is one of the causes of instability problems with
          the FT-100 Yaesu radios, so it's not just a matter of damaging an input
          device.)

          Chuck - N8DNX

          On Sun, 1 Oct 2006, Mark Vaughan wrote:

          > I agree with your risk here re the pin diodes.
          > However I have been running an ATAS120 in HF on one side of the car, and
          an
          > VHF/UHF Maldol on the other side.
          > SO FAR SO GOOD !!
          > I have experienced problems in the past running several radio's side by
          > side, with large close HF antennas, and both radio's running the same
          freq.
          > Things were OK up to 100W, but 400W caused damage.
          >
          > I know this is no definitive proof of anything, but a trend that is So Far
          > so Good!
          >
          > 73 Mark M0VAU






          [Non-text portions of this message have been removed]
        • g8hul
          ... problems, I ... radio on HF, ... inputs, Yaesu ... without ... Even a cursory glance at the circuit diagram will show that there are no pin diodes,
          Message 4 of 27 , Oct 2, 2006
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            > My issue though Charles was that whilst I would expect to get
            problems, I
            > don't.
            > I've only had problems when I've gone above 100W HF to another
            radio on HF,
            > so whilst the 897 and 857's have sensitive pin diodes on the
            inputs, Yaesu
            > seem to have allowed for the feedback that is common in such cases
            without
            > the need to dump anything with a diplexer or circulator.
            > 73 Mark M0VAU
            >

            Even a cursory glance at the circuit diagram will show that there
            are no pin diodes, 'sensitive' or otherwise, before filter elements
            that would reduce the HF signal to a low level. The pin diodes that
            are there are in parts of the circuit that are exposed to full power
            in band Tx signal levels anyway, so they can't be that sensitive!!
            This appears to be somewhat of a spurious argument.

            73
            Jeff
            G8HUL
          • Mark Vaughan
            Hi Jef I got into the middle of this without looking at the circuit diagrams. We have a member that was having problems with something wiping out his normal
            Message 5 of 27 , Oct 2, 2006
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              Hi Jef
              I got into the middle of this without looking at the circuit diagrams.
              We have a member that was having problems with something wiping out his
              normal public FM broadcast radio side of things.
              A number of comments were thrown around regarding the input stages (which I
              didn't check) and the possibility of overload from something powerful and
              close a good possibility, together with the possibility of damage to the
              input side due to it's lack of any relays and; again not having looked at
              the diagrams so i'll say; solid state input switching. If this was true then
              a normal twin antenna HF / VHFUHF vehicle setup would suffer, which it does
              not at 100W. Hence my comment.
              But as you point out it's a little missed up and confuses.

              73 Mark M0VAU


              _____

              From: FT897@yahoogroups.com [mailto:FT897@yahoogroups.com] On Behalf Of
              g8hul
              Sent: 02 October 2006 08:30
              To: FT897@yahoogroups.com
              Subject: Warning !!! Re: [FT897] Cause Identified!!!: FM station "bleeds"
              across entire 88-108 band Warning !!!



              > My issue though Charles was that whilst I would expect to get
              problems, I
              > don't.
              > I've only had problems when I've gone above 100W HF to another
              radio on HF,
              > so whilst the 897 and 857's have sensitive pin diodes on the
              inputs, Yaesu
              > seem to have allowed for the feedback that is common in such cases
              without
              > the need to dump anything with a diplexer or circulator.
              > 73 Mark M0VAU
              >

              Even a cursory glance at the circuit diagram will show that there
              are no pin diodes, 'sensitive' or otherwise, before filter elements
              that would reduce the HF signal to a low level. The pin diodes that
              are there are in parts of the circuit that are exposed to full power
              in band Tx signal levels anyway, so they can't be that sensitive!!
              This appears to be somewhat of a spurious argument.

              73
              Jeff
              G8HUL






              [Non-text portions of this message have been removed]
            • Charles Scott
              Mark: While damage in this way doesn t seem to happen all that often, it can happen to virtually any radio with enough power. Some may be able to handle a few
              Message 6 of 27 , Oct 2, 2006
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                Mark:
                While damage in this way doesn't seem to happen all that often, it can
                happen to virtually any radio with enough power. Some may be able to
                handle a few watts without damage and others perhaps more or less. It
                would be unwise to permit even 1 watt into any receiver if you can avoid
                it, so personally, I don't tempt fate. Your mileage may vary.

                Chuck - N8DNX

                On Sun, 1 Oct 2006, Mark Vaughan wrote:

                > My issue though Charles was that whilst I would expect to get problems, I
                > don't.
                > I've only had problems when I've gone above 100W HF to another radio on HF,
                > so whilst the 897 and 857's have sensitive pin diodes on the inputs, Yaesu
                > seem to have allowed for the feedback that is common in such cases without
                > the need to dump anything with a diplexer or circulator.
                > 73 Mark M0VAU
              • Craig Sharrow
                OK guys, you ve managed to fully scramble my already partially-addled brain. Are you saying that 2 antennas both tuned to the same freq should not be connected
                Message 7 of 27 , Oct 2, 2006
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                  OK guys, you've managed to fully scramble my already partially-addled
                  brain.

                  Are you saying that 2 antennas both tuned to the same freq should not
                  be connected to both the HF and VHF antenna inputs at the same time,
                  or what?

                  I assume that my 2m/70cm vertical isn't a problem with my dipole, if
                  each is only connected to its appropriate input, but it would be a
                  problem if I duplexed the dipole into both HF and VHF inputs and also
                  had the Diamond X50a connected to the VHF. Right or wrong?

                  Also, does this mean that a wide-band discone (like the Diamond D130J)
                  connected to the VHF/UHF input AND an 80m half-wave dipole would be a
                  problem?

                  Craig
                  K9LEG
                • Dan Eisenman
                  Craig; It would not be a good idea to have a HF antenna hooked to the UHF connector and then transmit on HF. The HF antenna will just pick up the RF and feed
                  Message 8 of 27 , Oct 2, 2006
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                    Craig;
                    It would not be a good idea to have a HF antenna hooked to the UHF
                    connector and then transmit on HF.
                    The HF antenna will just pick up the RF and feed it back into the radio
                    and could cause you problems.
                    I recently had a G5RV (80-10 meters) & a 40 meter dipole in different
                    locations but on the same roof.
                    I run about 900 watts out with a 3-500z amp .I have two separate coax
                    lines that go out to the roof. Just for
                    fun I was wondering how much RF was coming back in on the dipole
                    when I transmitted on the G5RV , I put a 100 watt light bulb on the
                    coax of the 40 meter dipole and with 900 watts out on the G5RV
                    it will light the 100 watt bulb on the 40 meter dipole.My guess is I'm
                    getting about 10 percent back.
                    So if you use the same ratio , at 100 watts out on 40 meters I would
                    get back around 10 watts back-that would fry the front end of
                    the FT-897D.
                    I currently have a 2 meter & 70 CM J pole on the UHF side and have no
                    problem from the G5RV because of the difference in frequency.
                    When you think about it you would not want any antenna that was
                    resonate at your transmitted frequency hooked up to the UHF connector.
                    It would not matter if the FT-897 was on or off , the RF if high enough
                    would damage the radio.
                    I have heard reports from Yaesu techs saying that when run mobile some
                    radios have been damaged with another mobile (very Close )
                    transmitting.
                    Hope this helps.

                    73
                    Dan
                    K8ICB in Florida


                    On Oct 2, 2006, at 5:09 PM, Craig Sharrow wrote:

                    OK guys, you've managed to fully scramble my already partially-addled
                    brain.

                    Are you saying that 2 antennas both tuned to the same freq should not
                    be connected to both the HF and VHF antenna inputs at the same time,
                    or what?

                    I assume that my 2m/70cm vertical isn't a problem with my dipole, if
                    each is only connected to its appropriate input, but it would be a
                    problem if I duplexed the dipole into both HF and VHF inputs and also
                    had the Diamond X50a connected to the VHF. Right or wrong?

                    Also, does this mean that a wide-band discone (like the Diamond D130J)
                    connected to the VHF/UHF input AND an 80m half-wave dipole would be a
                    problem?

                    Craig
                    K9LEG




                    [Non-text portions of this message have been removed]
                  • jeff w
                    ... Hi Mark Yes the thread does seem to have degenerated, with a lot of spurious comments. The guy has obviously got an overload problem, but he dosen t seem
                    Message 9 of 27 , Oct 5, 2006
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                      >Hi Jef
                      >I got into the middle of this without looking at the circuit diagrams.
                      >We have a member that was having problems with something wiping out his
                      >normal public FM broadcast radio side of things.
                      >A number of comments were thrown around regarding the input stages (which I
                      >didn't check) and the possibility of overload from something powerful and
                      >close a good possibility, together with the possibility of damage to the
                      >input side due to it's lack of any relays and; again not having looked at
                      >the diagrams so i'll say; solid state input switching. If this was true
                      >then
                      >a normal twin antenna HF / VHFUHF vehicle setup would suffer, which it does
                      >not at 100W. Hence my comment.
                      >But as you point out it's a little missed up and confuses.
                      >
                      >73 Mark M0VAU
                      >
                      >

                      Hi Mark

                      Yes the thread does seem to have degenerated, with a lot of spurious
                      comments. The guy has obviously got an overload problem, but he dosen't seem
                      able to work out if it is caused by a new strong local station or perhaps
                      damage to the front end.

                      As far as the input on the VHF side goes, there is no switching before what
                      ammounts to a diplexer that splits the vhf/uhf paths apart. It is only then
                      that there is tx/rx switching on each of the vhf and uhf paths.

                      Now that is not to say that you couldn't blow the fromt end by putting hf
                      signals into it, but you would need quite a lot of power, so the coupling
                      between antenna would have to be very high with a lot of tx power on hf!!

                      Regards
                      Jeff

                      _________________________________________________________________
                      Windows Live� Messenger has arrived. Click here to download it for free!
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                    • Patricia (Elaine) Gibbons
                      A possible solution would be a dual-band DCI bandpass filter which passes only 144-148, and 430-450 MHz .. I use one in my sedan primarily to reduce the amount
                      Message 10 of 27 , Oct 5, 2006
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                        A possible solution would be a dual-band DCI bandpass filter which
                        passes only
                        144-148, and 430-450 MHz .. I use one in my sedan primarily to
                        reduce the amount
                        of rx intermod from high-power vhf paging that would otherwise open
                        the squelch
                        on my dual-band mobile ..

                        the same type of filter could be connected to the VHF/UHF port on
                        the 897 ...

                        Here's the on that I installed :

                        http://www.dci.ca/pdf/DCI-146-444-DB.pdf

                        Trish
                        --
                        Patricia E. Gibbons & Carla Satra
                        Tactical Link Systems
                        <http://www.tactical-link.com>
                        Our comvan:
                        <http://www.tactical-link.com/wa6ube.htm>



                        -----Original Message-----
                        From: FT897@yahoogroups.com [mailto:FT897@yahoogroups.com]On Behalf
                        Of
                        jeff w
                        Sent: Thursday, October 05, 2006 12:18 AM
                        To: FT897@yahoogroups.com
                        Subject: RE: Warning !!! Re: [FT897] Cause Identified!!!: FM station
                        "bleeds" across entire 88-108 band Warning !!!

                        Hi Mark

                        Yes the thread does seem to have degenerated, with a lot of spurious
                        comments. The guy has obviously got an overload problem, but he
                        dosen't seem
                        able to work out if it is caused by a new strong local station or
                        perhaps
                        damage to the front end.

                        As far as the input on the VHF side goes, there is no switching
                        before what
                        ammounts to a diplexer that splits the vhf/uhf paths apart. It is
                        only then
                        that there is tx/rx switching on each of the vhf and uhf paths.

                        Now that is not to say that you couldn't blow the fromt end by
                        putting hf
                        signals into it, but you would need quite a lot of power, so the
                        coupling
                        between antenna would have to be very high with a lot of tx power on
                        hf!!

                        Regards
                        Jeff
                      • Charles Scott
                        Mark: I haven t had a chance to look yet, but it may be that those are not bandpass filters but rather high-pass and low-pass filters, which would be more
                        Message 11 of 27 , Oct 5, 2006
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                          Mark:
                          I haven't had a chance to look yet, but it may be that those are not
                          bandpass filters but rather high-pass and low-pass filters, which would be
                          more typical of that application.
                          Keep in mind also that capacitors in the front-end can be damaged by
                          excessive power on the input and some capacitor failure modes could result
                          in non-linear behavior.

                          Chuck - N8DNX


                          > Hi Mark
                          >
                          > As far as the input on the VHF side goes, there is no switching before what
                          > ammounts to a diplexer that splits the vhf/uhf paths apart. It is only then
                          > that there is tx/rx switching on each of the vhf and uhf paths.
                          >
                          > Now that is not to say that you couldn't blow the fromt end by putting hf
                          > signals into it, but you would need quite a lot of power, so the coupling
                          > between antenna would have to be very high with a lot of tx power on hf!!
                          >
                          > Regards
                          > Jeff
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