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Trouble with Transmitter section RXTX Ensemble

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  • jvilardo2000
    Just finished the final section on my RXTX Ensemble and I have some out of range measurements. I ran the tests suggested and detailed by G4ZFQ for the BS170 s
    Message 1 of 12 , Jan 18, 2013
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      Just finished the final section on my RXTX Ensemble and I have some out of range measurements.

      I ran the tests suggested and detailed by G4ZFQ for the BS170's and never got any voltages over 2 volts. 2.01, 2.01, 2.02, 1.98, 1.98, 1.97 were the voltages, none at or above 3.0 volts. I selected the 3 that were near 2.0 volts for Q5, Q7 and Q8.

      I ran the current test for receive and TX; Receive is right in the game at 25 ma but in tansmit I only get 60 ma not the 125ma expected.

      voltage drop accross R48 = 3mv, R49=3mv, hairpin R46 to gnd = 0.4mv,
      hairpin R35(PTT ACTIVE)to grnd 12.36V, hairpin R35 (NO PTT)=0

      Help will be greatly appreciated.

      Joe K3JV
    • Alan
      ... Subject: [softrock40] Trouble with Transmitter section RXTX Ensemble ... Joe, I think the test voltages you got are lower than anyone has reported but I d
      Message 2 of 12 , Jan 18, 2013
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        ----- Original Message -----
        Subject: [softrock40] Trouble with Transmitter section RXTX Ensemble


        > I ran the tests suggested and detailed by G4ZFQ for the BS170's and never got any voltages over 2 volts. 2.01, 2.01, 2.02, 1.98,
        > 1.98, 1.97 were the voltages, none at or above 3.0 volts. I selected the 3 that were near 2.0 volts for Q5, Q7 and Q8.
        >
        > I ran the current test for receive and TX; Receive is right in the game at 25 ma but in tansmit I only get 60 ma not the 125ma
        > expected.
        >
        > voltage drop accross R48 = 3mv, R49=3mv, hairpin R46 to gnd = 0.4mv,
        > hairpin R35(PTT ACTIVE)to grnd 12.36V, hairpin R35 (NO PTT)=0
        >

        Joe,

        I think the test voltages you got are lower than anyone has reported but I'd think that if they were all the same you would still
        get the correct R48/9 voltages. (Reason for low current readings).
        Please measure the voltages at R38, 39, 40, 41 which may give a clue.
        Measure the resistance to ground at R46 hairpin. (Power off)
        Check the soldering and look for splashes or even whiskers of PCB that have been left after manufacture.

        73 Alan G4ZFQ
      • barry underwood
        Joe, I had exactly that problem with mine after a couple of weeks of successful operation. After much head scratching, it turned out to be the surface mount
        Message 3 of 12 , Jan 19, 2013
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          Joe,

          I had exactly that problem with mine after a couple of weeks of successful operation. After much head scratching, it turned out to be the surface mount capacitor C67, which had decided that it would rather be a 160 Ohm resistor. (Maybe too much heat when soldering) This was effectively shorting out the bias for Q7 and Q8, which was around 0.7 Volt on R46/47 hairpin when the fault was apparent. I replaced C67 with a suitable ceramic and all is well again now.

          Baz G4BUD
        • Joe Vilardo
          Alan I re-checked voltage drop across R48 and R49. R48=0, R49=2.9. The following voltages to ground: NO PTT R38=0.2mv,R39=0.1mv, R40=0.1mv,R41=0.0mv PTT ON
          Message 4 of 12 , Jan 19, 2013
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            Alan
             
            I re-checked voltage drop across R48 and R49.  R48=0, R49=2.9.  The following voltages to ground: NO PTT R38=0.2mv,R39=0.1mv, R40=0.1mv,R41=0.0mv PTT ON R38=1.1V , R39=1.6V, R40 =1.02V, R41=0.1mv. R46 resistance to gnd=2430 ohms.
             
            Thanks,
            Joe
            From: Alan
            Sent: Saturday, January 19, 2013 2:34 AM
            Subject: Re: [softrock40] Trouble with Transmitter section RXTX Ensemble
             
             


            ----- Original Message -----
            Subject: [softrock40] Trouble with Transmitter section RXTX Ensemble

            > I ran the tests suggested and detailed by G4ZFQ for the BS170's and never got any voltages over 2 volts. 2.01, 2.01, 2.02, 1.98,
            > 1.98, 1.97 were the voltages, none at or above 3.0 volts. I selected the 3 that were near 2.0 volts for Q5, Q7 and Q8.
            >
            > I ran the current test for receive and TX; Receive is right in the game at 25 ma but in tansmit I only get 60 ma not the 125ma
            > expected.
            >
            > voltage drop accross R48 = 3mv, R49=3mv, hairpin R46 to gnd = 0.4mv,
            > hairpin R35(PTT ACTIVE)to grnd 12.36V, hairpin R35 (NO PTT)=0
            >

            Joe,

            I think the test voltages you got are lower than anyone has reported but I'd think that if they were all the same you would still
            get the correct R48/9 voltages. (Reason for low current readings).
            Please measure the voltages at R38, 39, 40, 41 which may give a clue.
            Measure the resistance to ground at R46 hairpin. (Power off)
            Check the soldering and look for splashes or even whiskers of PCB that have been left after manufacture.

            73 Alan G4ZFQ

          • Alan
            ... Subject: Re: [softrock40] Trouble with Transmitter section RXTX Ensemble ... Joe All low. Sorry I should have asked for R39 hairpin as well. If that is not
            Message 5 of 12 , Jan 19, 2013
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              ----- Original Message -----
              Subject: Re: [softrock40] Trouble with Transmitter section RXTX Ensemble


              >I re-checked voltage drop across R48 and R49. R48=0, R49=2.9. The following voltages to ground: NO PTT R38=0.2mv,R39=0.1mv,
              >R40=0.1mv,R41=0.0mv PTT ON R38=1.1V , R39=1.6V, R40 =1.02V, R41=0.1mv. R46 resistance to gnd=2430 ohms.

              Joe

              All low. Sorry I should have asked for R39 hairpin as well.
              If that is not around 12V then check it's value.
              And check S12V.
              Check all solder joints around Q5 and the other components mentioned.

              73 Alan G4ZFQ


              >
              > I ran the current test for receive and TX; Receive is right in the game at 25 ma but in tansmit I only get 60 ma not the 125ma
              > expected.
              >
              > voltage drop accross R48 = 3mv, R49=3mv, hairpin R46 to gnd = 0.4mv,
              > hairpin R35(PTT ACTIVE)to grnd 12.36V, hairpin R35 (NO PTT)=0
              >

              Joe,

              I think the test voltages you got are lower than anyone has reported but I'd think that if they were all the same you would still
              get the correct R48/9 voltages. (Reason for low current readings).
              Please measure the voltages at R38, 39, 40, 41 which may give a clue.
              Measure the resistance to ground at R46 hairpin. (Power off)
              Check the soldering and look for splashes or even whiskers of PCB that have been left after manufacture.

              73 Alan G4ZFQ
            • Joe Vilardo
              Alan I found one error, R39 & R40 reversed. I get 80ma now in the transmit mode. R48=0 & R49=3.1mv R39 =3.15 volts with PTT active. NO PTT R38=0, R40=0,
              Message 6 of 12 , Jan 19, 2013
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                Alan
                 
                I found one error, R39 & R40 reversed.  I get 80ma now in the transmit mode.  R48=0 & R49=3.1mv  R39 =3.15 volts with PTT active.
                NO PTT R38=0, R40=0, R41=0  PTT ON R38=2.5V, R40=1.68V, R41=.65V.
                12 volts supply = 12.6V
                 
                Joe
                 
                From: Alan
                Sent: Saturday, January 19, 2013 10:18 AM
                Subject: Re: [softrock40] Trouble with Transmitter section RXTX Ensemble
                 
                 


                ----- Original Message -----
                Subject: Re: [softrock40] Trouble with Transmitter section RXTX Ensemble

                >I re-checked voltage drop across R48 and R49. R48=0, R49=2.9. The following voltages to ground: NO PTT R38=0.2mv,R39=0.1mv,
                >R40=0.1mv,R41=0.0mv PTT ON R38=1.1V , R39=1.6V, R40 =1.02V, R41=0.1mv. R46 resistance to gnd=2430 ohms.

                Joe

                All low. Sorry I should have asked for R39 hairpin as well.
                If that is not around 12V then check it's value.
                And check S12V.
                Check all solder joints around Q5 and the other components mentioned.

                73 Alan G4ZFQ

                >
                > I ran the current test for receive and TX; Receive is right in the game at 25 ma but in tansmit I only get 60 ma not the 125ma
                > expected.
                >
                > voltage drop accross R48 = 3mv, R49=3mv, hairpin R46 to gnd = 0.4mv,
                > hairpin R35(PTT ACTIVE)to grnd 12.36V, hairpin R35 (NO PTT)=0
                >

                Joe,

                I think the test voltages you got are lower than anyone has reported but I'd think that if they were all the same you would still
                get the correct R48/9 voltages. (Reason for low current readings).
                Please measure the voltages at R38, 39, 40, 41 which may give a clue.
                Measure the resistance to ground at R46 hairpin. (Power off)
                Check the soldering and look for splashes or even whiskers of PCB that have been left after manufacture.

                73 Alan G4ZFQ

              • Alan
                ... Subject: Re: [softrock40] Trouble with Transmitter section RXTX Ensemble ... NO PTT R38=0, R40=0, R41=0 PTT ON R38=2.5V, R40=1.68V, R41=.65V. 12 volts
                Message 7 of 12 , Jan 19, 2013
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                  ----- Original Message -----
                  Subject: Re: [softrock40] Trouble with Transmitter section RXTX Ensemble


                  >I found one error, R39 & R40 reversed. I get 80ma now in the transmit mode. R48=0 & R49=3.1mv R39 =3.15 volts with PTT active.
                  NO PTT R38=0, R40=0, R41=0 PTT ON R38=2.5V, R40=1.68V, R41=.65V.
                  12 volts supply = 12.6V

                  Joe

                  Getting closer.
                  Check that R47 hairpin and the gates of Q7,8 are all at 2V5, the same as R38.
                  Check you have about 12V on the primary of T4 and Q7,8 drains.

                  73 Alan G4ZFQ

                  Subject: Re: [softrock40] Trouble with Transmitter section RXTX Ensemble

                  >I re-checked voltage drop across R48 and R49. R48=0, R49=2.9. The following voltages to ground: NO PTT R38=0.2mv,R39=0.1mv,
                  >R40=0.1mv,R41=0.0mv PTT ON R38=1.1V , R39=1.6V, R40 =1.02V, R41=0.1mv. R46 resistance to gnd=2430 ohms.

                  All low. Sorry I should have asked for R39 hairpin as well.
                  If that is not around 12V then check it's value.
                  And check S12V.
                  Check all solder joints around Q5 and the other components mentioned.
                • Joe Vilardo
                  From: Alan Sent: Sunday, January 20, 2013 2:13 AM To: softrock40@yahoogroups.com Subject: Re: [softrock40] Trouble with Transmitter section RXTX Ensemble ...
                  Message 8 of 12 , Jan 21, 2013
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                    From: Alan
                    Sent: Sunday, January 20, 2013 2:13 AM
                    Subject: Re: [softrock40] Trouble with Transmitter section RXTX Ensemble
                     
                     


                    ----- Original Message -----
                    Subject: Re: [softrock40] Trouble with Transmitter section RXTX Ensemble

                    >I found one error, R39 & R40 reversed. I get 80ma now in the transmit mode. R48=0 & R49=3.1mv R39 =3.15 volts with PTT active.
                    NO PTT R38=0, R40=0, R41=0 PTT ON R38=2.5V, R40=1.68V, R41=.65V.
                    12 volts supply = 12.6V

                    Joe

                    Getting closer.
                    Check that R47 hairpin and the gates of Q7,8 are all at 2V5, the same as R38.
                    Check you have about 12V on the primary of T4 and Q7,8 drains.

                    73 Alan G4ZFQ

                    ALAN

                    This is what I measured:

                    R47=2.54, Gate of Q7,Q8=2.54, R38=2.52, Drain of Q7,Q8=12.64. T4-P1,P2=12.64

                     

                    Thanks,

                    Joe



                    Subject: Re: [softrock40] Trouble with Transmitter section RXTX Ensemble

                    >I re-checked voltage drop across R48 and R49. R48=0, R49=2.9. The following voltages to ground: NO PTT R38=0.2mv,R39=0.1mv,
                    >R40=0.1mv,R41=0.0mv PTT ON R38=1.1V , R39=1.6V, R40 =1.02V, R41=0.1mv. R46 resistance to gnd=2430 ohms.

                    All low. Sorry I should have asked for R39 hairpin as well.
                    If that is not around 12V then check it's value.
                    And check S12V.
                    Check all solder joints around Q5 and the other components mentioned.

                  • Alan
                    ... Subject: Re: [softrock40] Trouble with Transmitter section RXTX Ensemble ... Check you have about 12V on the primary of T4 and Q7,8 drains. ... Joe, I
                    Message 9 of 12 , Jan 21, 2013
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                      ----- Original Message -----
                      Subject: Re: [softrock40] Trouble with Transmitter section RXTX Ensemble




                      >>Check that R47 hairpin and the gates of Q7,8 are all at 2V5, the same as R38.
                      Check you have about 12V on the primary of T4 and Q7,8 drains.

                      >This is what I measured:

                      >R47=2.54, Gate of Q7,Q8=2.54, R38=2.52, Drain of Q7,Q8=12.64. T4-P1,P2=12.64


                      Joe,

                      I wondered if that would be your reply.
                      All seems correct except that Q7,8 are not conducting.
                      Are they the correct way round?
                      Otherwise they seem suspect which is strange as they were tested when you did the balance check. But they are sensitive to static.
                      Unless someone else has any ideas I'd suggest replacing them.

                      73 Alan G4ZFQ



                      Subject: Re: [softrock40] Trouble with Transmitter section RXTX Ensemble

                      >I re-checked voltage drop across R48 and R49. R48=0, R49=2.9. The following voltages to ground: NO PTT R38=0.2mv,R39=0.1mv,
                      >R40=0.1mv,R41=0.0mv PTT ON R38=1.1V , R39=1.6V, R40 =1.02V, R41=0.1mv. R46 resistance to gnd=2430 ohms.

                      All low. Sorry I should have asked for R39 hairpin as well.
                      If that is not around 12V then check it's value.
                      And check S12V.
                      Check all solder joints around Q5 and the other components mentioned.
                    • Joe Vilardo
                      Alan I removed Q7 and Q8, re-tested them and they were both gone, must have been static, I didn’t use my wrist straps until I was installing Q7 and Q8. I
                      Message 10 of 12 , Jan 21, 2013
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                        Alan
                         
                        I removed Q7 and Q8, re-tested them and they were both gone, must have been static, I didn’t use my wrist straps until I was installing Q7 and Q8. I think I zapped them when I was shaping them for the 90 degree fit on the board, that’s when I didn’t have the wrist straps on.
                         
                        I had two remaining BS170’s one tested 2.98 V while the other was 2.01 V and I decided to install them even though there was a difference in their test voltage.  When I key the TXRX Ensemble now I get 115 ma of current draw on the 13.8 volt supply to the board. The measured drop across R48=40.1mv and R49=50.2mv   Is this variation acceptable? or should I look for 3 more that are closer to each other. I assume that if they tested closer in value then the drop between R48 and R49 would be closer as well?
                         
                        Alan, thanks for your remote trouble shooting and guiding hand.
                        Joe
                        From: Alan
                        Sent: Monday, January 21, 2013 2:02 PM
                        Subject: Re: [softrock40] Trouble with Transmitter section RXTX Ensemble
                         
                         


                        ----- Original Message -----
                        Subject: Re: [softrock40] Trouble with Transmitter section RXTX Ensemble

                        >>Check that R47 hairpin and the gates of Q7,8 are all at 2V5, the same as R38.
                        Check you have about 12V on the primary of T4 and Q7,8 drains.

                        >This is what I measured:

                        >R47=2.54, Gate of Q7,Q8=2.54, R38=2.52, Drain of Q7,Q8=12.64. T4-P1,P2=12.64

                        Joe,

                        I wondered if that would be your reply.
                        All seems correct except that Q7,8 are not conducting.
                        Are they the correct way round?
                        Otherwise they seem suspect which is strange as they were tested when you did the balance check. But they are sensitive to static.
                        Unless someone else has any ideas I'd suggest replacing them.

                        73 Alan G4ZFQ

                        Subject: Re: [softrock40] Trouble with Transmitter section RXTX Ensemble

                        >I re-checked voltage drop across R48 and R49. R48=0, R49=2.9. The following voltages to ground: NO PTT R38=0.2mv,R39=0.1mv,
                        >R40=0.1mv,R41=0.0mv PTT ON R38=1.1V , R39=1.6V, R40 =1.02V, R41=0.1mv. R46 resistance to gnd=2430 ohms.

                        All low. Sorry I should have asked for R39 hairpin as well.
                        If that is not around 12V then check it's value.
                        And check S12V.
                        Check all solder joints around Q5 and the other components mentioned.

                      • Joe Vilardo
                        Alan Correction to the previous note. The remaining 2 BS170 when tested measured 1.98 not 2.98 V and 2.01 Volts. Joe From: Joe Vilardo Sent: Monday, January
                        Message 11 of 12 , Jan 21, 2013
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                          Alan
                           
                          Correction to the previous note.  The remaining 2 BS170 when tested measured 1.98 not 2.98 V and 2.01 Volts.
                           
                          Joe
                           
                          Sent: Monday, January 21, 2013 6:33 PM
                          Subject: Re: [softrock40] Trouble with Transmitter section RXTX Ensemble
                           
                           

                          Alan
                           
                          I removed Q7 and Q8, re-tested them and they were both gone, must have been static, I didn’t use my wrist straps until I was installing Q7 and Q8. I think I zapped them when I was shaping them for the 90 degree fit on the board, that’s when I didn’t have the wrist straps on.
                           
                          I had two remaining BS170’s one tested 2.98 V while the other was 2.01 V and I decided to install them even though there was a difference in their test voltage.  When I key the TXRX Ensemble now I get 115 ma of current draw on the 13.8 volt supply to the board. The measured drop across R48=40.1mv and R49=50.2mv   Is this variation acceptable? or should I look for 3 more that are closer to each other. I assume that if they tested closer in value then the drop between R48 and R49 would be closer as well?
                           
                          Alan, thanks for your remote trouble shooting and guiding hand.
                          Joe
                          From: Alan
                          Sent: Monday, January 21, 2013 2:02 PM
                          Subject: Re: [softrock40] Trouble with Transmitter section RXTX Ensemble
                           
                           


                          ----- Original Message -----
                          Subject: Re: [softrock40] Trouble with Transmitter section RXTX Ensemble

                          >>Check that R47 hairpin and the gates of Q7,8 are all at 2V5, the same as R38.
                          Check you have about 12V on the primary of T4 and Q7,8 drains.

                          >This is what I measured:

                          >R47=2.54, Gate of Q7,Q8=2.54, R38=2.52, Drain of Q7,Q8=12.64. T4-P1,P2=12.64

                          Joe,

                          I wondered if that would be your reply.
                          All seems correct except that Q7,8 are not conducting.
                          Are they the correct way round?
                          Otherwise they seem suspect which is strange as they were tested when you did the balance check. But they are sensitive to static.
                          Unless someone else has any ideas I'd suggest replacing them.

                          73 Alan G4ZFQ

                          Subject: Re: [softrock40] Trouble with Transmitter section RXTX Ensemble

                          >I re-checked voltage drop across R48 and R49. R48=0, R49=2.9. The following voltages to ground: NO PTT R38=0.2mv,R39=0.1mv,
                          >R40=0.1mv,R41=0.0mv PTT ON R38=1.1V , R39=1.6V, R40 =1.02V, R41=0.1mv. R46 resistance to gnd=2430 ohms.

                          All low. Sorry I should have asked for R39 hairpin as well.
                          If that is not around 12V then check it's value.
                          And check S12V.
                          Check all solder joints around Q5 and the other components mentioned.

                        • Alan
                          ... Subject: Re: [softrock40] Trouble with Transmitter section RXTX Ensemble ... Joe Glad that got sorted out! very strange both BS170s failed. Yes the R48/49
                          Message 12 of 12 , Jan 21, 2013
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                            ----- Original Message -----
                            Subject: Re: [softrock40] Trouble with Transmitter section RXTX Ensemble


                            >Correction to the previous note. The remaining 2 BS170 when tested measured 1.98 not 2.98 V and 2.01 Volts.

                            Joe

                            Glad that got sorted out! very strange both BS170s failed.
                            Yes the R48/49 volts are quite acceptable.


                            73 Alan G4ZFQ


                            >I removed Q7 and Q8, re-tested them and they were both gone, must have been static, I didn’t use my wrist straps until I was
                            >installing Q7 and Q8. I think I zapped them when I was shaping them for the 90 degree fit on the board, that’s when I didn’t have
                            >the wrist straps on.

                            I had two remaining BS170’s one tested 2.98 V while the other was 2.01 V and I decided to install them even though there was a
                            difference in their test voltage. When I key the TXRX Ensemble now I get 115 ma of current draw on the 13.8 volt supply to the
                            board. The measured drop across R48=40.1mv and R49=50.2mv Is this variation acceptable? or should I look for 3 more that are
                            closer to each other. I assume that if they tested closer in value then the drop between R48 and R49 would be closer as well?
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