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Re: [softrock40] RXTX Ensemble Transmit PA Problem

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  • Alan
    ... Subject: [softrock40] RXTX Ensemble Transmit PA Problem ... Edward, Test point E is low, possibly this is stopping Q7, 8 from conducting. This could be
    Message 1 of 9 , Aug 27 11:44 PM
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      ----- Original Message -----
      Subject: [softrock40] RXTX Ensemble Transmit PA Problem


      > I finished all the assembly and the testing was going fine. I verified RFC1 and the 12V and it was good. I measured T3 and T4
      > and got 0 ohms on all 4 checks. I installed the FET stack and got 25.7 mA for rcv and then 80.1 mA on xmit. I checked voltage on
      > R48 and R49 and read 0.3 mV and 4.3 mV, can't say which is which. I then did test point E and got 2.13 VDC. On R35 I got 12.78 VDC
      > with PTT and 0 VDC with no PTT. At this point I stopped since I had a failure.
      > I went back today and verified 12.78 VDC on both Q8 and Q9 and 2.07 VDC on the gate, middle pin, when PTT is active. So, it
      > seems that one or both are not conducting.

      Edward,

      Test point E is low, possibly this is stopping Q7, 8 from conducting.
      This could be caused by a fault around Q4, 5.
      Or, it may be that Q5 is not matching Q7, 8. Occasionally there is one that, while still within specification, is a lot different
      from the others.

      I would be inclined to remove Q5, 7, 8 and check their matching along with the spares.
      <https://sites.google.com/site/g4zfqradio/matching-bs170-for-softrock> This would also show whether they are operating.

      You could first measure all the voltages around Q4, 5 and report.

      73 Alan G4ZFQ

      > Does that sound about right? Should I try to replace them with the last two after retesting all four of them. De-soldering the
      > current Q7 and Q8 of course. Is there other tests I can perform to check?
      > Mahalo,
      > >
      >
      >
      > ------------------------------------
      >
      > Yahoo! Groups Links
      >
      >
      >
    • Hiko
      Alan, I went back and examined everything and got this... Power Supply Voltage of 13.70Vdc from a MFJ Power Supply All dc wrt hairpin of R50 + Side of C23 Exp
      Message 2 of 9 , Aug 28 9:55 PM
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        Alan,
        I went back and examined everything and got this...
        Power Supply Voltage of 13.70Vdc from a MFJ Power Supply
        All dc wrt hairpin of R50
        + Side of C23 Exp 12Vdc Read 12.98Vdc
        T3 and T4 Resistance (all should be 0 ohms)
        A - A 0 Ohms
        B - B 0 Ohms
        C - C 0 Ohms
        D - D 0 Ohms
        Driver/PA Current (No USB Plugged in)
        Exp < 35mA Read 20.1mA
        Exp < 150mA Read 75.6mA
        Driver/PA Current (With USB Plugged in)
        Exp < 35mA Read 25.7mA
        Exp < 150mA Read 80.1mA
        ---Unplugged USB---
        BS170 Voltages when matching prior to install. (I forgot to mention I did do this before install)
        1.) 3.0 Vdc Used as Q7/Q8
        2.) 3.0 Vdc Used as Q7/Q8
        3.) 2.97 Vdc Used as Q5
        4.) 2.94 Vdc Spare
        5.) 2.94 Vdc Spare
        Across R48 (A) Exp 55mVdc Read 4.3mVdc No PTT Does not change with PTT
        Across R49 C Exp 55mVdc Read 0.4mVdc No PTT Does not change with PTT
        Test Point E Exp 2.2Vdc Read 2.08Vdc with PTT 0Vdc without PTT
        R35 PTT On Exp 12Vdc Read 12.8Vdc
        R35 PTT Off Exp 0Vdc Read 0Vdc
        R38 Same as junction of R46/R47
        Q7 Gate 2.09 Vdc
        Q7 Source same as across R48
        Q7 Drain 13.11 Vdc
        Q8 Gate 2.09 Vdc
        Q8 Source same as across R49
        Q8 Drain 13.02 Vdc
        R46 to Ground 22.2K Ohms
        R47 to Ground 22.2K Ohms
        R46/R47 junction to Ground 22.2K Ohms
        R37 11.63 Vdc
        R37/R39 Junction 11.62 Vdc
        R39 2.72 Vdc
        D3 Anode 2.72 Vdc
        D3 Cathode 2.08 Vdc
        R38/R40 Junction 1.19 Vdc
        R41 0.66 Vdc

        Mahalo for the help....
        Edward WH7TT
        --- In softrock40@yahoogroups.com, "Alan" <alan4alan@...> wrote:
        >
        >
        > ----- Original Message -----
        > Subject: [softrock40] RXTX Ensemble Transmit PA Problem
        >
        >
        > > I finished all the assembly and the testing was going fine. I verified RFC1 and the 12V and it was good. I measured T3 and T4
        > > and got 0 ohms on all 4 checks. I installed the FET stack and got 25.7 mA for rcv and then 80.1 mA on xmit. I checked voltage on
        > > R48 and R49 and read 0.3 mV and 4.3 mV, can't say which is which. I then did test point E and got 2.13 VDC. On R35 I got 12.78 VDC
        > > with PTT and 0 VDC with no PTT. At this point I stopped since I had a failure.
        > > I went back today and verified 12.78 VDC on both Q8 and Q9 and 2.07 VDC on the gate, middle pin, when PTT is active. So, it
        > > seems that one or both are not conducting.
        >
        > Edward,
        >
        > Test point E is low, possibly this is stopping Q7, 8 from conducting.
        > This could be caused by a fault around Q4, 5.
        > Or, it may be that Q5 is not matching Q7, 8. Occasionally there is one that, while still within specification, is a lot different
        > from the others.
        >
        > I would be inclined to remove Q5, 7, 8 and check their matching along with the spares.
        > <https://sites.google.com/site/g4zfqradio/matching-bs170-for-softrock> This would also show whether they are operating.
        >
        > You could first measure all the voltages around Q4, 5 and report.
        >
        > 73 Alan G4ZFQ
        >
        > > Does that sound about right? Should I try to replace them with the last two after retesting all four of them. De-soldering the
        > > current Q7 and Q8 of course. Is there other tests I can perform to check?
        > > Mahalo,
        > > >
        > >
        > >
        > > ------------------------------------
        > >
        > > Yahoo! Groups Links
        > >
        > >
        > >
        >
      • Alan
        ... Subject: [softrock40] Re: RXTX Ensemble Transmit PA Problem ... Edward, So we should expect about 3V at Test Point E. ... I should have said before, it
        Message 3 of 9 , Aug 29 12:00 AM
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          ----- Original Message -----
          Subject: [softrock40] Re: RXTX Ensemble Transmit PA Problem

          > Driver/PA Current (With USB Plugged in)
          > Exp < 35mA Read 25.7mA
          > Exp < 150mA Read 80.1mA
          > ---Unplugged USB---
          > BS170 Voltages when matching prior to install. (I forgot to mention I did do this before install)
          > 1.) 3.0 Vdc Used as Q7/Q8
          > 2.) 3.0 Vdc Used as Q7/Q8
          > 3.) 2.97 Vdc Used as Q5
          > 4.) 2.94 Vdc Spare
          > 5.) 2.94 Vdc Spare

          Edward,

          So we should expect about 3V at Test Point E.

          > Across R48 (A) Exp 55mVdc Read 4.3mVdc No PTT Does not change with PTT
          > Across R49 C Exp 55mVdc Read 0.4mVdc No PTT Does not change with PTT

          I should have said before, it seems there is a small current flowing through Q7, and a tiny current through Q8.
          I think this could be pointing to a fault in Q7, 8. You may have been right in the first place.

          Remove them, check the voltage at R46/47 hairpins.
          You could test Q7, 8 as you did when you checked the balance.

          73 Alan G4ZFQ

          > Test Point E Exp 2.2Vdc Read 2.08Vdc with PTT 0Vdc without PTT
          > R35 PTT On Exp 12Vdc Read 12.8Vdc
          > R35 PTT Off Exp 0Vdc Read 0Vdc
          > R38 Same as junction of R46/R47
          > Q7 Gate 2.09 Vdc
          > Q7 Source same as across R48
          > Q7 Drain 13.11 Vdc
          > Q8 Gate 2.09 Vdc
          > Q8 Source same as across R49
          > Q8 Drain 13.02 Vdc
          > R46 to Ground 22.2K Ohms
          > R47 to Ground 22.2K Ohms
          > R46/R47 junction to Ground 22.2K Ohms
          > R37 11.63 Vdc
          > R37/R39 Junction 11.62 Vdc
          > R39 2.72 Vdc
          > D3 Anode 2.72 Vdc
          > D3 Cathode 2.08 Vdc
          > R38/R40 Junction 1.19 Vdc
          > R41 0.66 Vdc
          >
        • haniyasu_hiko
          Alan, I removed old Q7 and Q8 and reinstalled new ones. I missed the part about checking R46/47 Hairpins. Was this while Q7 and Q8 were out? I did the readings
          Message 4 of 9 , Aug 29 11:41 PM
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            Alan,

               I removed old Q7 and Q8 and reinstalled new ones. I missed the part about checking R46/47 Hairpins. Was this while Q7 and Q8 were out? I did the readings again with the new set and got...

            8/29/13
            Power Supply Voltage of 13.70Vdc from a MFJ Power Supply
            All dc wrt hairpin of R50

            (Doing matching)

            Old Q7 11.8Vdc and Q8 12.5Vdc (Fried)

            New Pair (Matched them again to be sure)
            1.) 3.02 Vdc Used as Q7/Q8
            2.) 3.02 Vdc Used as Q7/Q8


            Put in new Q7 and Q8

            Driver/PA Current (With USB Plugged in)
            Exp < 35mA  Read 23.8mA
            Exp < 150mA Read 80.3mA
            Across R48 (A) Exp 55mVdc Read 1.6mVdc with PTT 0Vdc without PTT
            Across R49 (C) Exp 55mVdc Read 1.6mVdc with PTT 0Vdc without PTT
            Test Point E Exp 2.2Vdc Read 2.12Vdc with PTT 0Vdc without PTT
            Q7 Gate 2.11 Vdc
            Q7 Source same as across R48
            Q7 Drain 12.97 Vdc
            Q8 Gate 2.11 Vdc
            Q8 Source same as across R49
            Q8 Drain 12.97 Vdc
            R35 PTT On Exp 12Vdc Read 12.69Vdc
            R35 PTT Off Exp 0Vdc Read 0Vdc

            All following with PTT On

            R37 12.69 Vdc
            R37/R39 11.51 Vdc
            R39 2.73 Vdc
            D3 Anode 2.73 Vdc
            D3 Cathode 2.09 Vdc
            R38/R40 1.21 Vdc
            R41 0.65 Vdc

            Mahalo,

            Edward



            --- In softrock40@yahoogroups.com, <alan4alan@...> wrote:

            ----- Original Message -----
            Subject: [softrock40] Re: RXTX Ensemble Transmit PA Problem

            > Driver/PA Current (With USB Plugged in)
            > Exp < 35mA Read 25.7mA
            > Exp < 150mA Read 80.1mA
            > ---Unplugged USB---
            > BS170 Voltages when matching prior to install. (I forgot to mention I did do this before install)
            > 1.) 3.0 Vdc Used as Q7/Q8
            > 2.) 3.0 Vdc Used as Q7/Q8
            > 3.) 2.97 Vdc Used as Q5
            > 4.) 2.94 Vdc Spare
            > 5.) 2.94 Vdc Spare

            Edward,

            So we should expect about 3V at Test Point E.

            > Across R48 (A) Exp 55mVdc Read 4.3mVdc No PTT Does not change with PTT
            > Across R49 C Exp 55mVdc Read 0.4mVdc No PTT Does not change with PTT

            I should have said before, it seems there is a small current flowing through Q7, and a tiny current through Q8.
            I think this could be pointing to a fault in Q7, 8. You may have been right in the first place.

            Remove them, check the voltage at R46/47 hairpins.
            You could test Q7, 8 as you did when you checked the balance.

            73 Alan G4ZFQ

            > Test Point E Exp 2.2Vdc Read 2.08Vdc with PTT 0Vdc without PTT
            > R35 PTT On Exp 12Vdc Read 12.8Vdc
            > R35 PTT Off Exp 0Vdc Read 0Vdc
            > R38 Same as junction of R46/R47
            > Q7 Gate 2.09 Vdc
            > Q7 Source same as across R48
            > Q7 Drain 13.11 Vdc
            > Q8 Gate 2.09 Vdc
            > Q8 Source same as across R49
            > Q8 Drain 13.02 Vdc
            > R46 to Ground 22.2K Ohms
            > R47 to Ground 22.2K Ohms
            > R46/R47 junction to Ground 22.2K Ohms
            > R37 11.63 Vdc
            > R37/R39 Junction 11.62 Vdc
            > R39 2.72 Vdc
            > D3 Anode 2.72 Vdc
            > D3 Cathode 2.08 Vdc
            > R38/R40 Junction 1.19 Vdc
            > R41 0.66 Vdc
            >
          • Alan
            ... Subject: RE: Re: [softrock40] Re: RXTX Ensemble Transmit PA Problem ... So you have two problems! These are pointing to good Q7, 8 and bad bias circuit.
            Message 5 of 9 , Aug 30 3:38 AM
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              ----- Original Message -----
              Subject: RE: Re: [softrock40] Re: RXTX Ensemble Transmit PA Problem


              >
              >
              > Put in new Q7 and Q8
              >
              > Driver/PA Current (With USB Plugged in)
              > Exp < 35mA Read 23.8mA
              > Exp < 150mA Read 80.3mA
              > Across R48 (A) Exp 55mVdc Read 1.6mVdc with PTT 0Vdc without PTT
              > Across R49 (C) Exp 55mVdc Read 1.6mVdc with PTT 0Vdc without PTT

              So you have two problems! These are pointing to good Q7, 8 and bad bias circuit.

              > Test Point E Exp 2.2Vdc Read 2.12Vdc with PTT 0Vdc without PTT
              > Q7 Gate 2.11 Vdc
              > Q7 Source same as across R48
              > Q7 Drain 12.97 Vdc
              > Q8 Gate 2.11 Vdc

              Test point E should be something near the voltage you got when matching. More like 3V0 than Robby's 2V2. This is controlled by Q5
              and the components around it.
              I wonder if Q5 has also failed?
              Check the values and soldering of all components around Q4, 5 but I think Q5 is most likely the problem.
              Do you have a lot of dry static in WH7 land? Be careful these MOFETS are vulnerable.

              73 Alan G4ZFQ

              > Q8 Source same as across R49
              > Q8 Drain 12.97 Vdc
              > R35 PTT On Exp 12Vdc Read 12.69Vdc
              > R35 PTT Off Exp 0Vdc Read 0Vdc
              >
              >
              > All following with PTT On
              >
              >
              > R37 12.69 Vdc
              > R37/R39 11.51 Vdc
              > R39 2.73 Vdc
              > D3 Anode 2.73 Vdc
              > D3 Cathode 2.09 Vdc
              > R38/R40 1.21 Vdc
              > R41 0.65 Vdc
              >
            • haniyasu_hiko
              Alan, Again many thanks for the help. I think you may be right and perhaps the best option would be to get 5 more MOSFETs and then replace Q5 and see what is
              Message 6 of 9 , Aug 31 2:37 PM
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                 Alan,

                    Again many thanks for the help. I think you may be right and perhaps the best option would be to get 5 more MOSFETs and then replace Q5 and see what is happening after that. I used the last two. I am not sure where or who I would email to order more parts. Any ideas?

                   Before I do though I am going to do some more resistance measurements and verify all the components and solder joints.

                Mahalo,

                Edward, WH7TT



                --- In softrock40@yahoogroups.com, <alan4alan@...> wrote:

                ----- Original Message -----
                Subject: RE: Re: [softrock40] Re: RXTX Ensemble Transmit PA Problem


                >
                >
                > Put in new Q7 and Q8
                >
                > Driver/PA Current (With USB Plugged in)
                > Exp < 35mA Read 23.8mA
                > Exp < 150mA Read 80.3mA
                > Across R48 (A) Exp 55mVdc Read 1.6mVdc with PTT 0Vdc without PTT
                > Across R49 (C) Exp 55mVdc Read 1.6mVdc with PTT 0Vdc without PTT

                So you have two problems! These are pointing to good Q7, 8 and bad bias circuit.

                > Test Point E Exp 2.2Vdc Read 2.12Vdc with PTT 0Vdc without PTT
                > Q7 Gate 2.11 Vdc
                > Q7 Source same as across R48
                > Q7 Drain 12.97 Vdc
                > Q8 Gate 2.11 Vdc

                Test point E should be something near the voltage you got when matching. More like 3V0 than Robby's 2V2. This is controlled by Q5
                and the components around it.
                I wonder if Q5 has also failed?
                Check the values and soldering of all components around Q4, 5 but I think Q5 is most likely the problem.
                Do you have a lot of dry static in WH7 land? Be careful these MOFETS are vulnerable.

                73 Alan G4ZFQ

                > Q8 Source same as across R49
                > Q8 Drain 12.97 Vdc
                > R35 PTT On Exp 12Vdc Read 12.69Vdc
                > R35 PTT Off Exp 0Vdc Read 0Vdc
                >
                >
                > All following with PTT On
                >
                >
                > R37 12.69 Vdc
                > R37/R39 11.51 Vdc
                > R39 2.73 Vdc
                > D3 Anode 2.73 Vdc
                > D3 Cathode 2.09 Vdc
                > R38/R40 1.21 Vdc
                > R41 0.65 Vdc
                >
              • Dave Miller
                Digikey will have the parts. Getting a few extra lets you match the PA ones Dave Sent from my iPhone
                Message 7 of 9 , Aug 31 3:09 PM
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                  Digikey will have the parts.  
                  Getting a few extra lets you match the PA ones
                  Dave 

                  Sent from my iPhone

                  On 2013-08-31, at 14:37, <haniyasu_hiko@...> wrote:

                   

                   Alan,

                      Again many thanks for the help. I think you may be right and perhaps the best option would be to get 5 more MOSFETs and then replace Q5 and see what is happening after that. I used the last two. I am not sure where or who I would email to order more parts. Any ideas?

                     Before I do though I am going to do some more resistance measurements and verify all the components and solder joints.

                  Mahalo,

                  Edward, WH7TT



                  --- In softrock40@yahoogroups.com, <alan4alan@...> wrote:

                  ----- Original Message -----
                  Subject: RE: Re: [softrock40] Re: RXTX Ensemble Transmit PA Problem


                  >
                  >
                  > Put in new Q7 and Q8
                  >
                  > Driver/PA Current (With USB Plugged in)
                  > Exp < 35mA Read 23.8mA
                  > Exp < 150mA Read 80.3mA
                  > Across R48 (A) Exp 55mVdc Read 1.6mVdc with PTT 0Vdc without PTT
                  > Across R49 (C) Exp 55mVdc Read 1.6mVdc with PTT 0Vdc without PTT

                  So you have two problems! These are pointing to good Q7, 8 and bad bias circuit.

                  > Test Point E Exp 2.2Vdc Read 2.12Vdc with PTT 0Vdc without PTT
                  > Q7 Gate 2.11 Vdc
                  > Q7 Source same as across R48
                  > Q7 Drain 12.97 Vdc
                  > Q8 Gate 2.11 Vdc

                  Test point E should be something near the voltage you got when matching. More like 3V0 than Robby's 2V2. This is controlled by Q5
                  and the components around it.
                  I wonder if Q5 has also failed?
                  Check the values and soldering of all components around Q4, 5 but I think Q5 is most likely the problem.
                  Do you have a lot of dry static in WH7 land? Be careful these MOFETS are vulnerable.

                  73 Alan G4ZFQ

                  > Q8 Source same as across R49
                  > Q8 Drain 12.97 Vdc
                  > R35 PTT On Exp 12Vdc Read 12.69Vdc
                  > R35 PTT Off Exp 0Vdc Read 0Vdc
                  >
                  >
                  > All following with PTT On
                  >
                  >
                  > R37 12.69 Vdc
                  > R37/R39 11.51 Vdc
                  > R39 2.73 Vdc
                  > D3 Anode 2.73 Vdc
                  > D3 Cathode 2.09 Vdc
                  > R38/R40 1.21 Vdc
                  > R41 0.65 Vdc
                  >

                • haniyasu_hiko
                  Alan, Dave, Thanks for the help. I have a new set of BS170s on their way. Is there any testing I can do after I pull q5 to see if anything else sis wrong? Or
                  Message 8 of 9 , Sep 2, 2013
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                    Alan, Dave,

                        Thanks for the help. I have a new set of BS170s on their way. Is there any testing I can do after I pull q5 to see if anything else sis wrong? Or should I just match the best 3 out of 5 and go with that once the BS170s arrive?

                    Mahalo,

                    Edward



                    --- In softrock40@yahoogroups.com, <ve7pke@...> wrote:

                    Digikey will have the parts.  
                    Getting a few extra lets you match the PA ones
                    Dave 

                    Sent from my iPhone

                    On 2013-08-31, at 14:37, <haniyasu_hiko@...> wrote:

                     

                     Alan,

                        Again many thanks for the help. I think you may be right and perhaps the best option would be to get 5 more MOSFETs and then replace Q5 and see what is happening after that. I used the last two. I am not sure where or who I would email to order more parts. Any ideas?

                       Before I do though I am going to do some more resistance measurements and verify all the components and solder joints.

                    Mahalo,

                    Edward, WH7TT



                    --- In softrock40@yahoogroups.com, <alan4alan@...> wrote:

                    ----- Original Message -----
                    Subject: RE: Re: [softrock40] Re: RXTX Ensemble Transmit PA Problem


                    >
                    >
                    > Put in new Q7 and Q8
                    >
                    > Driver/PA Current (With USB Plugged in)
                    > Exp < 35mA Read 23.8mA
                    > Exp < 150mA Read 80.3mA
                    > Across R48 (A) Exp 55mVdc Read 1.6mVdc with PTT 0Vdc without PTT
                    > Across R49 (C) Exp 55mVdc Read 1.6mVdc with PTT 0Vdc without PTT

                    So you have two problems! These are pointing to good Q7, 8 and bad bias circuit.

                    > Test Point E Exp 2.2Vdc Read 2.12Vdc with PTT 0Vdc without PTT
                    > Q7 Gate 2.11 Vdc
                    > Q7 Source same as across R48
                    > Q7 Drain 12.97 Vdc
                    > Q8 Gate 2.11 Vdc

                    Test point E should be something near the voltage you got when matching. More like 3V0 than Robby's 2V2. This is controlled by Q5
                    and the components around it.
                    I wonder if Q5 has also failed?
                    Check the values and soldering of all components around Q4, 5 but I think Q5 is most likely the problem.
                    Do you have a lot of dry static in WH7 land? Be careful these MOFETS are vulnerable.

                    73 Alan G4ZFQ

                    > Q8 Source same as across R49
                    > Q8 Drain 12.97 Vdc
                    > R35 PTT On Exp 12Vdc Read 12.69Vdc
                    > R35 PTT Off Exp 0Vdc Read 0Vdc
                    >
                    >
                    > All following with PTT On
                    >
                    >
                    > R37 12.69 Vdc
                    > R37/R39 11.51 Vdc
                    > R39 2.73 Vdc
                    > D3 Anode 2.73 Vdc
                    > D3 Cathode 2.09 Vdc
                    > R38/R40 1.21 Vdc
                    > R41 0.65 Vdc
                    >
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