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BS170 in Ensemble RXTX

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  • oe8pck
    Hi to the Group, I have just found something which might be of interest to the group. Q8 and Q7 appear to have large differences. I found this out using
    Message 1 of 27 , Apr 28 12:58 AM
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      Hi to the Group,
      I have just found something which might be of interest to the group.
      Q8 and Q7 appear to have large differences. I found this out using Robbie's builders notes and checking the static voltages over R48 and R49. My initial voltages with the PTT active were 63 mV and 34 mV. At first I checked all the voltages around the BS170s and found these to be correct an then changed the Q8 for another and then I got 72 mV instead of the 34 mV. I now have 63 mV and 72 mV which is within the spec. that Robbie describes. Just a matter of interest.

      Having great fun with the Ensemble RXTX and now get 1 Watt out.

      Can any one describe how to use a Mike with this equipment? I guess it is the same as the RXTX v6.3 but i would like to know the points used on the board.

      73 to all

      de Paul OE8PCK
    • Alan
      ... Subject: [softrock40] BS170 in Ensemble RXTX ... Yes, this has worried several builders. Your variation is probably larger than any other reported. I
      Message 2 of 27 , Apr 28 1:26 AM
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        ----- Original Message -----
        Subject: [softrock40] BS170 in Ensemble RXTX



        > Q8 and Q7 appear to have large differences. I found this out using
        > Robbie's builders notes and checking the static voltages over R48 and R49.
        > My initial voltages with the PTT active were 63 mV and 34 mV. At first I
        > checked all the voltages around the BS170s and found these to be correct
        > an then changed the Q8 for another and then I got 72 mV instead of the 34
        > mV. I now have 63 mV and 72 mV which is within the spec. that Robbie
        > describes. Just a matter of interest.
        >

        Yes, this has worried several builders. Your variation is probably larger
        than any other reported.
        I expect most devices are somewhere in the middle of their specified range.
        Sometimes one that is further from this mid point is found.
        We usually say that more than Robby describes is acceptable but yours was a
        big difference.

        >
        > Can any one describe how to use a Mike with this equipment? I guess it is
        > the same as the RXTX v6.3 but i would like to know the points used on the
        > board.
        >

        Yes, it is the same as the 6.3, you connect a mike to the soundcard.

        73 Alan G4ZFQ
      • Oliver Goldenstein
        Hi! Thanks for your Info Paul. I have to check this with my RXTXs again. What Band Coverage has your RXTX You are referring to? 73 de Oliver, DL6KBG Von meinem
        Message 3 of 27 , Apr 28 3:36 AM
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          Hi!

          Thanks for your Info Paul.

          I have to check this with my RXTXs again.

          What Band Coverage has your RXTX
          You are referring to?

          73 de Oliver, DL6KBG

          Von meinem iPhone gesendet

          Am 28.04.2011 um 09:58 schrieb "oe8pck" <oe8pck@...>:

          > Hi to the Group,
          > I have just found something which might be of interest to the group.
          > Q8 and Q7 appear to have large differences. I found this out using Robbie's builders notes and checking the static voltages over R48 and R49. My initial voltages with the PTT active were 63 mV and 34 mV. At first I checked all the voltages around the BS170s and found these to be correct an then changed the Q8 for another and then I got 72 mV instead of the 34 mV. I now have 63 mV and 72 mV which is within the spec. that Robbie describes. Just a matter of interest.
          >
          > Having great fun with the Ensemble RXTX and now get 1 Watt out.
          >
          > Can any one describe how to use a Mike with this equipment? I guess it is the same as the RXTX v6.3 but i would like to know the points used on the board.
          >
          > 73 to all
          >
          > de Paul OE8PCK
          >
          >
          >
          >
          >
          > ------------------------------------
          >
          > Yahoo! Groups Links
          >
          >
          >
        • g8voip
          Hi Paul, Glad you got that sorted out. If the FETs are supplied on a strip, I always use two of them for the PA output stage. Usually those from the same batch
          Message 4 of 27 , Apr 28 4:01 AM
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            Hi Paul,

            Glad you got that sorted out.

            If the FETs are supplied on a strip, I always use two of them for the PA output stage. Usually those from the same batch have reasonably similar characteristics.

            If they are loose, no way of telling easily until you power them up unless you make a simple test jig to match them.

            73, Bob G8VOI


            --- In softrock40@yahoogroups.com, Oliver Goldenstein <oliver.goldenstein@...> wrote:
            >
            > Hi!
            >
            > Thanks for your Info Paul.
            >
            > I have to check this with my RXTXs again.
            >
            > What Band Coverage has your RXTX
            > You are referring to?
            >
            > 73 de Oliver, DL6KBG
            >
            > Von meinem iPhone gesendet
            >
            > Am 28.04.2011 um 09:58 schrieb "oe8pck" <oe8pck@...>:
            >
            > > Hi to the Group,
            > > I have just found something which might be of interest to the group.
            > > Q8 and Q7 appear to have large differences. I found this out using Robbie's builders notes and checking the static voltages over R48 and R49. My initial voltages with the PTT active were 63 mV and 34 mV. At first I checked all the voltages around the BS170s and found these to be correct an then changed the Q8 for another and then I got 72 mV instead of the 34 mV. I now have 63 mV and 72 mV which is within the spec. that Robbie describes. Just a matter of interest.
            > >
            > > Having great fun with the Ensemble RXTX and now get 1 Watt out.
            > >
            > > Can any one describe how to use a Mike with this equipment? I guess it is the same as the RXTX v6.3 but i would like to know the points used on the board.
            > >
            > > 73 to all
            > >
            > > de Paul OE8PCK
            > >
            > >
            > >
            > >
            > >
            > > ------------------------------------
            > >
            > > Yahoo! Groups Links
            > >
            > >
            > >
            >
          • oe8pck
            I am using the 10, 14 18 Mhz bands. If I whistle into the mike on SSB I get a max of 33dBm which is 2 Watts. I not intend to drive this hard though. I will
            Message 5 of 27 , Apr 28 4:45 AM
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              I am using the 10, 14 18 Mhz bands. If I whistle into the mike on SSB I get a max of 33dBm which is 2 Watts. I not intend to drive this hard though. I will settle for 1 W and drive a small PA.

              73 de Paul OE8PCK

              --- In softrock40@yahoogroups.com, Oliver Goldenstein <oliver.goldenstein@...> wrote:
              >
              > Hi!
              >
              > Thanks for your Info Paul.
              >
              > I have to check this with my RXTXs again.
              >
              > What Band Coverage has your RXTX
              > You are referring to?
              >
              > 73 de Oliver, DL6KBG
              >
              > Von meinem iPhone gesendet
              >
              > Am 28.04.2011 um 09:58 schrieb "oe8pck" <oe8pck@...>:
              >
              > > Hi to the Group,
              > > I have just found something which might be of interest to the group.
              > > Q8 and Q7 appear to have large differences. I found this out using Robbie's builders notes and checking the static voltages over R48 and R49. My initial voltages with the PTT active were 63 mV and 34 mV. At first I checked all the voltages around the BS170s and found these to be correct an then changed the Q8 for another and then I got 72 mV instead of the 34 mV. I now have 63 mV and 72 mV which is within the spec. that Robbie describes. Just a matter of interest.
              > >
              > > Having great fun with the Ensemble RXTX and now get 1 Watt out.
              > >
              > > Can any one describe how to use a Mike with this equipment? I guess it is the same as the RXTX v6.3 but i would like to know the points used on the board.
              > >
              > > 73 to all
              > >
              > > de Paul OE8PCK
              > >
              > >
              > >
              > >
              > >
              > > ------------------------------------
              > >
              > > Yahoo! Groups Links
              > >
              > >
              > >
              >
            • Oliver Goldenstein
              Now i have a problem with my RXRX 40/30/20 Meters. I lost half of the power and checked the Voltages at R48 and R49. On R48 i have: 1,19 V with PTT enabled. On
              Message 6 of 27 , Apr 28 11:52 PM
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                Now i have a problem with my RXRX 40/30/20 Meters.

                I lost half of the power and checked the Voltages at R48 and R49. On R48 i have:

                1,19 V with PTT enabled.

                On R49 i have the normal 56 Millivolt.

                I already replaced Q7. This Transceiver worked up to three months with
                more than one Watt. But i never used it with more than 500 mW.

                Only thing i can imagine, that during the measurements in comparison
                to my new RXTX 15/12/10 i messed something up.

                But what causes the 1,19 Volt?

                Thanks in Advance, Oliver

                On 28 April 2011 13:45, oe8pck <oe8pck@...> wrote:
                >
                > I am using the 10, 14 18 Mhz bands. If I whistle into the mike on SSB I get a max of 33dBm which is 2 Watts. I not intend to drive this hard though. I will settle for 1 W and drive a small PA.
                >
                > 73 de Paul OE8PCK
                >
                > --- In softrock40@yahoogroups.com, Oliver Goldenstein <oliver.goldenstein@...> wrote:
                >>
                >> Hi!
                >>
                >> Thanks for your Info Paul.
                >>
                >> I have to check this with my RXTXs again.
                >>
                >> What Band Coverage has your RXTX
                >> You are referring to?
                >>
                >> 73 de Oliver, DL6KBG
                >>
                >> Von meinem iPhone gesendet
                >>
                >> Am 28.04.2011 um 09:58 schrieb "oe8pck" <oe8pck@...>:
                >>
                >> > Hi to the Group,
                >> > I have just found something which might be of interest to the group.
                >> > Q8 and Q7 appear to have large differences. I found this out using Robbie's builders notes and checking the static voltages over R48 and R49. My initial voltages with the PTT active were 63 mV and 34 mV. At first I checked all the voltages around the BS170s and found these to be correct an then changed the Q8 for another and then I got 72 mV instead of the 34 mV. I now have 63 mV and 72 mV which is within the spec. that Robbie describes. Just a matter of interest.
                >> >
                >> > Having great fun with the Ensemble RXTX and now get 1 Watt out.
                >> >
                >> > Can any one describe how to use a Mike with this equipment? I guess it is the same as the RXTX v6.3 but i would like to know the points used on the board.
                >> >
                >> > 73 to all
                >> >
                >> > de Paul OE8PCK
                >> >
                >> >
                >> >
                >> >
                >> >
                >> > ------------------------------------
                >> >
                >> > Yahoo! Groups Links
                >> >
                >> >
                >> >
                >>
                >
                >
                >
                >
                > ------------------------------------
                >
                > Yahoo! Groups Links
                >
                >
                >
                >



                --
                Oliver, DL6KBG, JO61UB
                Blog: http://dl6kbg.blogspot.com
              • Alan
                ... From: Oliver Subject: Re: [softrock40] Re: BS170 in Ensemble RXTX ... Oliver, This would seem to point to a faulty Q7. This gives 540mA flowing through
                Message 7 of 27 , Apr 29 12:19 AM
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                  ----- Original Message -----
                  From: "Oliver
                  Subject: Re: [softrock40] Re: BS170 in Ensemble RXTX


                  > Now i have a problem with my RXRX 40/30/20 Meters.
                  >
                  > I lost half of the power and checked the Voltages at R48 and R49. On R48 i
                  > have:
                  >
                  > 1,19 V with PTT enabled.
                  >
                  > On R49 i have the normal 56 Millivolt.
                  >
                  > I already replaced Q7. This Transceiver worked up to three months with
                  > more than one Watt. But i never used it with more than 500 mW.
                  >

                  Oliver,

                  This would seem to point to a faulty Q7.
                  This gives 540mA flowing through R48 and Q7, R48 would get warm.
                  The other possibility is a bad joint on R48, or it has changed value.
                  What current is taken by the Softrock?

                  73 Alan G4ZFQ
                • Oliver Goldenstein
                  Good Morning Alan! ... I checked everything, but not that Resistor. It was blown up. Replaced it and everything is as it should. Thanks Alan ! 73 Oliver,
                  Message 8 of 27 , Apr 29 1:18 AM
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                    Good Morning Alan!

                    > The other possibility is a bad joint on R48, or it has changed value.

                    I checked everything, but not that Resistor. It was blown up. Replaced
                    it and everything is as it should.

                    Thanks Alan !

                    73 Oliver, DL6KBG

                    --
                    Oliver, DL6KBG, JO61UB
                    Blog: http://dl6kbg.blogspot.com
                  • k5nwa
                    Keep checking, resistors don t just blow up without a reason. ... Cecil k5nwa
                    Message 9 of 27 , Apr 29 5:39 AM
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                      Keep checking, resistors don't just blow up without a reason.

                      At 03:18 AM 4/29/2011, you wrote:
                      >Good Morning Alan!
                      >
                      > > The other possibility is a bad joint on R48, or it has changed value.
                      >
                      >I checked everything, but not that Resistor. It was blown up. Replaced
                      >it and everything is as it should.
                      >
                      >Thanks Alan !
                      >
                      >73 Oliver, DL6KBG
                      >
                      >--
                      >Oliver, DL6KBG, JO61UB
                      >Blog: http://dl6kbg.blogspot.com
                      >

                      Cecil
                      k5nwa
                      < www.softrockradio.org > < http://thepartsplace.k5nwa.com/ >
                      < http://parts.softrockradio.org/ >

                      Never take life seriously. Nobody gets out alive anyway.
                    • skeller1953
                      Group, Just arrived at the final test stage and obtained the exact same measurements across R48 and R49 previously reported by Paul (OE8PCK, 37mV and 65mV). I
                      Message 10 of 27 , May 1, 2011
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                        Group,

                        Just arrived at the final test stage and obtained the exact same measurements across R48 and R49 previously reported by Paul (OE8PCK, 37mV and 65mV). I have ordered a replacement BS 170.

                        Is this a common problem?

                        Steve K
                        K2DKT

                        --- In softrock40@yahoogroups.com, "oe8pck" <oe8pck@...> wrote:
                        >
                        >
                        > I am using the 10, 14 18 Mhz bands. If I whistle into the mike on SSB I get a max of 33dBm which is 2 Watts. I not intend to drive this hard though. I will settle for 1 W and drive a small PA.
                        >
                        > 73 de Paul OE8PCK
                        >
                        > --- In softrock40@yahoogroups.com, Oliver Goldenstein <oliver.goldenstein@> wrote:
                        > >
                        > > Hi!
                        > >
                        > > Thanks for your Info Paul.
                        > >
                        > > I have to check this with my RXTXs again.
                        > >
                        > > What Band Coverage has your RXTX
                        > > You are referring to?
                        > >
                        > > 73 de Oliver, DL6KBG
                        > >
                        > > Von meinem iPhone gesendet
                        > >
                        > > Am 28.04.2011 um 09:58 schrieb "oe8pck" <oe8pck@>:
                        > >
                        > > > Hi to the Group,
                        > > > I have just found something which might be of interest to the group.
                        > > > Q8 and Q7 appear to have large differences. I found this out using Robbie's builders notes and checking the static voltages over R48 and R49. My initial voltages with the PTT active were 63 mV and 34 mV. At first I checked all the voltages around the BS170s and found these to be correct an then changed the Q8 for another and then I got 72 mV instead of the 34 mV. I now have 63 mV and 72 mV which is within the spec. that Robbie describes. Just a matter of interest.
                        > > >
                        > > > Having great fun with the Ensemble RXTX and now get 1 Watt out.
                        > > >
                        > > > Can any one describe how to use a Mike with this equipment? I guess it is the same as the RXTX v6.3 but i would like to know the points used on the board.
                        > > >
                        > > > 73 to all
                        > > >
                        > > > de Paul OE8PCK
                        > > >
                        > > >
                        > > >
                        > > >
                        > > >
                        > > > ------------------------------------
                        > > >
                        > > > Yahoo! Groups Links
                        > > >
                        > > >
                        > > >
                        > >
                        >
                      • grahamg3zod
                        Steve, could well be. I ve just got to the final tests stage as well. In my case both are low: 34.9mV 39.8mV This fails both of the limits in the Buider s
                        Message 11 of 27 , May 1, 2011
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                          Steve, could well be.  I've just got to the final tests stage as well.  In my case both are low:

                          34.9mV   39.8mV

                          This fails both of the limits in the Buider's Guide (not within 10% of 55mV and the difference of 4.9mV is more than 3.735mV (10% average of the two voltages).

                          However, it's generating around 1 watt on 15m and I'm not convinced it's necessary to start swapping BS170's - anyone have thoughts on this?

                          73 de Graham G3ZOD FISTS #8385
                          http://www.fists.co.uk


                          --- In softrock40@yahoogroups.com, "skeller1953" <skeller53@...> wrote:
                          > Just arrived at the final test stage and obtained the exact same measurements across R48 and R49 previously reported by Paul (OE8PCK, 37mV and 65mV). I have ordered a replacement BS 170.
                          >
                          > Is this a common problem?
                          >
                          > Steve K
                          > K2DKT

                        • Alan
                          ... Subject: [softrock40] Re: BS170 in Ensemble RXTX ... Steve, I would say it is not unexpected. The actual tolerances of the BS170 would probably give a
                          Message 12 of 27 , May 1, 2011
                          • 0 Attachment
                            ----- Original Message -----
                            Subject: [softrock40] Re: BS170 in Ensemble RXTX



                            > Just arrived at the final test stage and obtained the exact same
                            > measurements across R48 and R49 previously reported by Paul (OE8PCK, 37mV
                            > and 65mV). I have ordered a replacement BS 170.
                            >
                            > Is this a common problem?
                            >

                            Steve,

                            I would say it is not unexpected.
                            The actual tolerances of the BS170 would probably give a possible range of
                            even more than that.
                            I do not know when it actually becomes a problem. It seems reasonable that
                            they should be matched.
                            I wonder what difference it actually makes?
                            There must be other factors to be considered if they are to be considered
                            matched?

                            Graham, Robby's figures are often just taken from the actual one he built,
                            they are not necessarily typical.

                            73 Alan G4ZFQ
                          • Sid Boyce
                            ... Mine are 40.6mV and 32.1mV respectively but I have low gain 2x the voltage at the gates, so I m going to change them, hoping that from a batch of 5 from RS
                            Message 13 of 27 , May 1, 2011
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                              On 01/05/11 16:55, Alan wrote:
                              >
                              > ----- Original Message -----
                              > Subject: [softrock40] Re: BS170 in Ensemble RXTX
                              >
                              > > Just arrived at the final test stage and obtained the exact same
                              > > measurements across R48 and R49 previously reported by Paul (OE8PCK,
                              > 37mV
                              > > and 65mV). I have ordered a replacement BS 170.
                              > >
                              > > Is this a common problem?
                              > >
                              >
                              > Steve,
                              >
                              > I would say it is not unexpected.
                              > The actual tolerances of the BS170 would probably give a possible range of
                              > even more than that.
                              > I do not know when it actually becomes a problem. It seems reasonable that
                              > they should be matched.
                              > I wonder what difference it actually makes?
                              > There must be other factors to be considered if they are to be considered
                              > matched?
                              >
                              > Graham, Robby's figures are often just taken from the actual one he built,
                              > they are not necessarily typical.
                              >
                              > 73 Alan G4ZFQ
                              >
                              Mine are 40.6mV and 32.1mV respectively but I have low gain 2x the
                              voltage at the gates, so I'm going to change them, hoping that from a
                              batch of 5 from RS they will be fairly well matched.
                              73 ... Sid.
                              >


                              --
                              Sid Boyce ... Hamradio License G3VBV, Licensed Private Pilot
                              Emeritus IBM/Amdahl Mainframes and Sun/Fujitsu Servers Tech Support
                              Senior Staff Specialist, Cricket Coach
                              Microsoft Windows Free Zone - Linux used for all Computing Tasks
                            • grahamg3zod
                              Similar to my results but a little more extreme. Both my BS170s came off a strip of three, by the way. It d be interesting to know the significance of the
                              Message 14 of 27 , May 1, 2011
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                                Similar to my results but a little more extreme.  Both my BS170s came off a strip of three, by the way.  It'd be interesting to know the significance of the differences - different gains or is it just a case of the bias voltages really need to be different/adjustable for the two transistors?

                                73 de Graham G3ZOD FISTS #8385
                                http://www.fists.co.uk


                                --- In softrock40@yahoogroups.com, Sid Boyce <sboyce@...> wrote:
                                > Mine are 40.6mV and 32.1mV respectively but I have low gain 2x the
                                > voltage at the gates, so I'm going to change them, hoping that from a
                                > batch of 5 from RS they will be fairly well matched.
                                > 73 ... Sid.

                              • Sid Boyce
                                I had been wondering the same, but varying one may cause the other to vary also and you end up with driving one into saturation. The other idea would be to
                                Message 15 of 27 , May 1, 2011
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                                  I had been wondering the same, but varying one may cause the other to
                                  vary also and you end up with driving one into saturation.
                                  The other idea would be to feed the secondary of T3 through 0.1 caps to
                                  the gates and apply separate bias voltages to the gates, but if the 2
                                  FET's are not nearly matched same situation could occur.
                                  73 ... Sid.

                                  On 01/05/11 18:02, grahamg3zod wrote:
                                  > Similar to my results but a little more extreme. Both my BS170s came off
                                  > a strip of three, by the way. It'd be interesting to know the
                                  > significance of the differences - different gains or is it just a case
                                  > of the bias voltages really need to be different/adjustable for the two
                                  > transistors?
                                  >
                                  > 73 de Graham G3ZOD FISTS #8385
                                  > http://www.fists.co.uk
                                  >
                                  >
                                  > --- In softrock40@yahoogroups.com, Sid Boyce <sboyce@...> wrote:
                                  > > Mine are 40.6mV and 32.1mV respectively but I have low gain 2x the
                                  > > voltage at the gates, so I'm going to change them, hoping that from a
                                  > > batch of 5 from RS they will be fairly well matched.
                                  > > 73 ... Sid.
                                  >
                                  >


                                  --
                                  Sid Boyce ... Hamradio License G3VBV, Licensed Private Pilot
                                  Emeritus IBM/Amdahl Mainframes and Sun/Fujitsu Servers Tech Support
                                  Senior Staff Specialist, Cricket Coach
                                  Microsoft Windows Free Zone - Linux used for all Computing Tasks
                                • Sid Boyce
                                  I replaced both BS170 s in the PA stage and I have lots of RF out. Driving it with a tone generator program under Linux and I get 20V peak at the antenna. R48
                                  Message 16 of 27 , May 1, 2011
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                                    I replaced both BS170's in the PA stage and I have lots of RF out.
                                    Driving it with a tone generator program under Linux and I get 20V peak
                                    at the antenna.
                                    R48 = 46.5mV and R49 = 42.51mV.
                                    The heatsink gets pretty warm now, before there was no warmth.

                                    The originals were from the kit and the new ones, which I guessed would
                                    probably be from the same batch, came as a sealed set from RS Components.
                                    73 ... Sid.

                                    On 01/05/11 20:27, Sid Boyce wrote:
                                    > I had been wondering the same, but varying one may cause the other to
                                    > vary also and you end up with driving one into saturation.
                                    > The other idea would be to feed the secondary of T3 through 0.1 caps to
                                    > the gates and apply separate bias voltages to the gates, but if the 2
                                    > FET's are not nearly matched same situation could occur.
                                    > 73 ... Sid.
                                    >
                                    > On 01/05/11 18:02, grahamg3zod wrote:
                                    >> Similar to my results but a little more extreme. Both my BS170s came off
                                    >> a strip of three, by the way. It'd be interesting to know the
                                    >> significance of the differences - different gains or is it just a case
                                    >> of the bias voltages really need to be different/adjustable for the two
                                    >> transistors?
                                    >>
                                    >> 73 de Graham G3ZOD FISTS #8385
                                    >> http://www.fists.co.uk
                                    >>
                                    >>
                                    >> --- In softrock40@yahoogroups.com, Sid Boyce<sboyce@...> wrote:
                                    >> > Mine are 40.6mV and 32.1mV respectively but I have low gain 2x the
                                    >> > voltage at the gates, so I'm going to change them, hoping that from a
                                    >> > batch of 5 from RS they will be fairly well matched.
                                    >> > 73 ... Sid.
                                    >>
                                    >>
                                    >
                                    >


                                    --
                                    Sid Boyce ... Hamradio License G3VBV, Licensed Private Pilot
                                    Emeritus IBM/Amdahl Mainframes and Sun/Fujitsu Servers Tech Support
                                    Senior Staff Specialist, Cricket Coach
                                    Microsoft Windows Free Zone - Linux used for all Computing Tasks
                                  • grahamg3zod
                                    Sid, great news! For comparison, I wonder if you have a measurement of the RF out before you replaced them? Interestingly, one of your new readings is still
                                    Message 17 of 27 , May 2, 2011
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                                      Sid, great news!  For comparison, I wonder if you have a measurement of the RF out before you replaced them?

                                      Interestingly, one of your new readings is still out of spec. as far as the Builders' Guide is concerned - 42.51mV is below 45mV (55mV +/-10mV).  I know someone will say that the guide values are only approximate, but that is why the range is included and perhaps the 'Guide needs to make this broader, say +/- 15mV?

                                      My heatsink gets warm and I am measuring 1 watt out, but I'm driving it fairly hard with the audio from Rocky almost full on and the Delta 44 output level set to +4dBu (it's maximum setting).  Still a bit undecided whether to leave it alone or not.

                                      73 de Graham G3ZOD FISTS #8385
                                      http://www.fists.co.uk

                                      --- In softrock40@yahoogroups.com, Sid Boyce <sboyce@...> wrote:
                                      > I replaced both BS170's in the PA stage and I have lots of RF out.
                                      > Driving it with a tone generator program under Linux and I get 20V peak
                                      > at the antenna.
                                      > R48 = 46.5mV and R49 = 42.51mV.
                                      > The heatsink gets pretty warm now, before there was no warmth.
                                      >
                                      > The originals were from the kit and the new ones, which I guessed would
                                      > probably be from the same batch, came as a sealed set from RS Components.
                                      > 73 ... Sid.

                                    • Alan
                                      ... Subject: [softrock40] Re: BS170 in Ensemble RXTX - SUCCESS! ... the Builders Guide is concerned - 42.51mV is below 45mV (55mV +/-10mV). I know someone
                                      Message 18 of 27 , May 2, 2011
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                                        ----- Original Message -----

                                        Subject: [softrock40] Re: BS170 in Ensemble RXTX - SUCCESS!




                                        >Interestingly, one of your new readings is still out of spec. as far as
                                        the Builders' Guide is concerned - 42.51mV is below 45mV (55mV +/-10mV).
                                        I know someone will say that the guide values are only approximate, but
                                        that is why the range is included and perhaps the 'Guide needs to make
                                        this broader, say +/- 15mV?

                                        Graham,

                                        We need someone to actually give a proper analysis of this.
                                        I'm sure Robby will tell you he is no more of an electronics expert than I
                                        am. His skill is in producing construction instructions. It is difficult
                                        with a project like this to give absolute tolerances. Some readings may be
                                        expected to be very close to nominal, others like PA current, can vary a
                                        lot.
                                        The general consensus is that a wider spread is acceptable, but how much?
                                        If it really is critical perhaps the best match of the three should be
                                        selected before construction.


                                        >My heatsink gets warm and I am measuring 1 watt out, but I'm driving it
                                        fairly hard with the audio from Rocky almost full on and the Delta 44
                                        output level set to +4dBu (it's maximum setting). Still a bit undecided
                                        whether to leave it alone or not.

                                        It seems to me the rough and ready criteria is the same as any PA. Run it at
                                        least a couple of dB less power than you get when you force it.
                                        My Delta 44 will drive a Softrock to nearly one watt when set to the
                                        "Consumer" level. That is with a 12V4 PSU.
                                        Maybe I'm too careful but I keep mine at 1/2 watt. One watt makes far more
                                        difference to the heatsink temperature than it does to the signal at the
                                        other end.
                                        However, many claim to use it at 1 watt or even more.

                                        73 Alan G4ZFQ
                                      • Sid Boyce
                                        I know 42.51mV (static reading with PTT on) is below spec, but I m getting RF out at a decent level now. I am not too keen to go through endless replacements.
                                        Message 19 of 27 , May 2, 2011
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                                          I know 42.51mV (static reading with PTT on) is below spec, but I'm
                                          getting RF out at a decent level now. I am not too keen to go through
                                          endless replacements. I'm thinking of using a jig to match up a pair.
                                          73 ... Sid.

                                          Before replacement the RF out was only around 4V p-p.
                                          On 02/05/11 11:34, grahamg3zod wrote:
                                          > Sid, great news! For comparison, I wonder if you have a measurement of
                                          > the RF out before you replaced them?
                                          >
                                          > Interestingly, one of your new readings is still out of spec. as far as
                                          > the Builders' Guide is concerned - 42.51mV is below 45mV (55mV +/-10mV).
                                          > I know someone will say that the guide values are only approximate, but
                                          > that is why the range is included and perhaps the 'Guide needs to make
                                          > this broader, say +/- 15mV?
                                          >
                                          > My heatsink gets warm and I am measuring 1 watt out, but I'm driving it
                                          > fairly hard with the audio from Rocky almost full on and the Delta 44
                                          > output level set to +4dBu (it's maximum setting). Still a bit undecided
                                          > whether to leave it alone or not.
                                          >
                                          > 73 de Graham G3ZOD FISTS #8385
                                          > http://www.fists.co.uk
                                          >
                                          > --- In softrock40@yahoogroups.com, Sid Boyce <sboyce@...> wrote:
                                          > > I replaced both BS170's in the PA stage and I have lots of RF out.
                                          > > Driving it with a tone generator program under Linux and I get 20V peak
                                          > > at the antenna.
                                          > > R48 = 46.5mV and R49 = 42.51mV.
                                          > > The heatsink gets pretty warm now, before there was no warmth.
                                          > >
                                          > > The originals were from the kit and the new ones, which I guessed would
                                          > > probably be from the same batch, came as a sealed set from RS Components.
                                          > > 73 ... Sid.
                                          >
                                          >


                                          --
                                          Sid Boyce ... Hamradio License G3VBV, Licensed Private Pilot
                                          Emeritus IBM/Amdahl Mainframes and Sun/Fujitsu Servers Tech Support
                                          Senior Staff Specialist, Cricket Coach
                                          Microsoft Windows Free Zone - Linux used for all Computing Tasks
                                        • grahamg3zod
                                          Hi Alan and thanks for the comments. Which band(s) were you using with the audio settings you describe? I did try looking at a BS170 data sheet, but as my
                                          Message 20 of 27 , May 3, 2011
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                                            Hi Alan and thanks for the comments.  Which band(s) were you using with the audio settings you describe?

                                            I did try looking at a BS170 data sheet, but as my knowledge of electronics is limited, I found it fairly tough to understand, other than to note that some parameters have wide variations noted in the sheet.

                                            With the audio settings full on, I was getting a bit more than 1.5 watts on 15m, so I did back it off to 1 watt.  I tried it out on 12m and 10m yesterday and was getting, with the same audio settings, 0.8 watt on 12m and 0.6 watt on 10m, so all looks satisfactory to me despite the (apparently) low drain/source standing current on the BS170's.

                                            The previous comments about the heat sink just getting warm were misleading - touching the surface of of the vertical fins feels warm but putting a finger against the side of the heat sink revealed that it was actually pretty hot rather than warm (this is using CW rather than 100% duty cycle).

                                            I think I'll leave the transceiver as-is now unless someone comes up with a good reason to find PA transistors that run with a higher drain/source current.

                                            73 de Graham G3ZOD FISTS #8385
                                            http://www.fists.co.uk


                                            --- In softrock40@yahoogroups.com, "Alan" <alan4alan@...> wrote:
                                            > We need someone to actually give a proper analysis of this.
                                            > I'm sure Robby will tell you he is no more of an electronics expert than I
                                            > am. His skill is in producing construction instructions. It is difficult
                                            > with a project like this to give absolute tolerances. Some readings may be
                                            > expected to be very close to nominal, others like PA current, can vary a
                                            > lot.
                                            > The general consensus is that a wider spread is acceptable, but how much?
                                            > If it really is critical perhaps the best match of the three should be
                                            > selected before construction.
                                            > ...
                                            > It seems to me the rough and ready criteria is the same as any PA. Run it at
                                            > least a couple of dB less power than you get when you force it.
                                            > My Delta 44 will drive a Softrock to nearly one watt when set to the
                                            > "Consumer" level. That is with a 12V4 PSU.
                                            > Maybe I'm too careful but I keep mine at 1/2 watt. One watt makes far more
                                            > difference to the heatsink temperature than it does to the signal at the
                                            > other end.
                                            > However, many claim to use it at 1 watt or even more.
                                            >
                                            > 73 Alan G4ZFQ

                                          • Alan
                                            ... Subject: [softrock40] Re: BS170 in Ensemble RXTX - SUCCESS! ... the audio settings you describe? Graham, To elaborate. I have 3 RXTXs a 6.1 80/60/40m. 6.3
                                            Message 21 of 27 , May 3, 2011
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                                              ----- Original Message -----
                                              Subject: [softrock40] Re: BS170 in Ensemble RXTX - SUCCESS!



                                              >Which band(s) were you using with
                                              the audio settings you describe?

                                              Graham,

                                              To elaborate.
                                              I have 3 RXTXs a 6.1 80/60/40m. 6.3 160-10m. Ensemble 30/20/17m.
                                              I believe all have the same circuit components and values.
                                              I now run the Delta 44 at -4dBu and attenuate/reduce gain so each will
                                              deliver almost 1 watt maximum.
                                              Each step of the D44 control gives 6dB less power. I used this setup so I
                                              could easily use flea-power with WSPR using the TX audio adjustment and/or
                                              the D44 steps.

                                              The 6.1 has an extra 33K in the opamp input = 43K. I reckon that makes the
                                              op-amp gain 0.23, power ~ -13dB.
                                              The 6.3 has a crude attenuator/gain reduction which I reckon gives it -8dB.
                                              This Softrock gives at least 500mW except on 10m. (400mW max) I'm not sure
                                              if more audio will increase 10m power. I run it at 200mW, waiting for REAL
                                              sunspots.
                                              The Ensemble has an extra 10K in the opamp input = 20K. I reckon that
                                              makes the op-amp gain 0.5, power ~-6dB

                                              >I did try looking at a BS170 data sheet, but as my knowledge of
                                              electronics is limited, I found it fairly tough to understand, other
                                              than to note that some parameters have wide variations noted in the
                                              sheet.

                                              In all the years I have played radio I have avoided the mathematical and
                                              theoretical side as much as possible.
                                              My guess is that the Gate Threshold Voltage range of 0.8 to 3V for 1mA will
                                              be reflected at higher voltages, leading to the differences we see.
                                              But if the Gate Threshold Voltage of a device was 3V it seems that no
                                              current would flow but it would still be in spec??

                                              73 Alan G4ZFQ
                                            • taka_sugi1206
                                              Hello Paul. I had also same problem, but not so large difference as yours. The difference is very important and affects to TX IMD, output power. I suggest to
                                              Message 22 of 27 , May 5, 2011
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                                                Hello Paul.
                                                I had also same problem, but not so large difference as yours.
                                                The difference is very important and affects to TX IMD, output power.

                                                I suggest to buy many BS170s and select almost same Is(FET source current) BS170s by using simple test circuit as follows.

                                                Vd=12v, Rd(Drain load resistor)=1kohm, Rs(source resistor)=2.2ohm,
                                                Vg(gate bias)=2.2 ¨C 2.5v, and then measure the voltage of Rs.

                                                For my RXTX, voltage of R48,R49 is 54mv(24.5mA),53mv(24.1mA)each, and
                                                max output power is about 1w, 3 rd order IMD : about 25dB£À0.7w output

                                                73 de Taka, JA1TLH
                                              • Adam Sampson
                                                ... It might be worth having a guide to matching BS170s in the build instructions. The BS170s in my RXTX aren t very well matched, and they re cheap enough
                                                Message 23 of 27 , May 6, 2011
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                                                  Sid Boyce <sboyce@...> writes:

                                                  > I'm thinking of using a jig to match up a pair.

                                                  It might be worth having a guide to matching BS170s in the build
                                                  instructions. The BS170s in my RXTX aren't very well matched, and
                                                  they're cheap enough (and useful enough for other purposes) that buying
                                                  a couple of dozen to sort through is practical.

                                                  --
                                                  Adam Sampson <ats@...> <http://offog.org/>
                                                • Oliver Goldenstein
                                                  ... thanks for that circuit Taka! 73 de Oliver, DL6KBG -- Oliver, DL6KBG, JO61UB Blog: http://dl6kbg.blogspot.com
                                                  Message 24 of 27 , May 6, 2011
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                                                    > I suggest to buy many BS170s and select almost same Is(FET source current) BS170s  by  using  simple test circuit as follows.
                                                    >
                                                    >  Vd=12v, Rd(Drain load resistor)=1kohm, Rs(source resistor)=2.2ohm,
                                                    >  Vg(gate bias)=2.2 ¨C 2.5v,  and then measure the voltage of Rs.

                                                    thanks for that circuit Taka!

                                                    73 de Oliver, DL6KBG

                                                    --
                                                    Oliver, DL6KBG, JO61UB
                                                    Blog: http://dl6kbg.blogspot.com
                                                  • Sid Boyce
                                                    ... I have 8 more around, just a matter of when I can get around to matching up a pair. 73 ... Sid. -- Sid Boyce ... Hamradio License G3VBV, Licensed Private
                                                    Message 25 of 27 , May 6, 2011
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                                                      On 06/05/11 13:15, Adam Sampson wrote:
                                                      > Sid Boyce <sboyce@... <mailto:sboyce%40blueyonder.co.uk>>
                                                      > writes:
                                                      >
                                                      > > I'm thinking of using a jig to match up a pair.
                                                      >
                                                      > It might be worth having a guide to matching BS170s in the build
                                                      > instructions. The BS170s in my RXTX aren't very well matched, and
                                                      > they're cheap enough (and useful enough for other purposes) that buying
                                                      > a couple of dozen to sort through is practical.
                                                      >
                                                      > --
                                                      > Adam Sampson <ats@... <mailto:ats%40offog.org>> <http://offog.org/>
                                                      >

                                                      I have 8 more around, just a matter of when I can get around to matching
                                                      up a pair.
                                                      73 ... Sid.
                                                      --
                                                      Sid Boyce ... Hamradio License G3VBV, Licensed Private Pilot
                                                      Emeritus IBM/Amdahl Mainframes and Sun/Fujitsu Servers Tech Support
                                                      Senior Staff Specialist, Cricket Coach
                                                      Microsoft Windows Free Zone - Linux used for all Computing Tasks
                                                    • taka_sugi1206
                                                      Hello, Oliver Sorry, there was one mistake... Rd= 1kohm is too large, pse change to 100 ohm. Please note heat of the FET . I bought many BS170s of
                                                      Message 26 of 27 , May 8, 2011
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                                                        Hello, Oliver

                                                        Sorry, there was one mistake...
                                                        Rd= 1kohm is too large, pse change to 100 ohm.
                                                        Please note "heat of the FET".

                                                        I bought many BS170s of Fairchild,Mot, On-Semi and selected BS170‚"
                                                        by using this simple test circuit.

                                                        73@de Taka/JA1TLH


                                                        > > I suggest to buy many BS170s and select almost same Is(FET source current) BS170s  by  using  simple test circuit as follows.
                                                        > >
                                                        > >  Vd=12v, Rd(Drain load resistor)=1kohm, Rs(source resistor)=2.2ohm,
                                                        > >  Vg(gate bias)=2.2 ¨C 2.5v,  and then measure the voltage of Rs.
                                                        >
                                                        > thanks for that circuit Taka!
                                                        >
                                                        > 73 de Oliver, DL6KBG
                                                        >
                                                        > --
                                                        > Oliver, DL6KBG, JO61UB
                                                        > Blog: http://dl6kbg.blogspot.com
                                                        >
                                                      • Hugh
                                                        ... Me too. I am building up RxTx kits numbers 2 and 3, and decided to test all 18 BS170s Tony sent to me (after finding considerable inbalance in the first
                                                        Message 27 of 27 , Jul 23, 2011
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                                                          > > Q8 and Q7 appear to have large differences...
                                                          >
                                                          > Yes, this has worried several builders.

                                                          Me too.

                                                          I am building up RxTx kits numbers 2 and 3, and decided to test all 18 BS170s Tony sent to me (after finding considerable inbalance in the first kit I built.. well outside the construction notes)

                                                          Nature of test: put +2.20V on the gate, drain with 1KOhm in series, Source with 2.2Ohms and measure the source current.

                                                          I know this basically only measures the gate turn-on, but this is probably the most important for the matching between the PA pair and the bias transistor, as both PA transistors share a common bias voltage in the circuit.
                                                          Results: (mA) (in order as they appear on the stips)
                                                          25, 25, 37, 14, 25, 27, 12, 14, 9, 26, 9, 16, 39, 39, 23, 14

                                                          OK, the test is rough and ready, but I there is quite some variation (factor of 4 in current) (I will not be using the 9mA device)
                                                          Devices were fresh from the silver-strip and ESD precations were observed. I don't know if something 'nasty' happend between USA and Europe in shipping, but I doubt it. I will be using the 3x 25mA and the 3x39 for the Pa/Bias 3 transistors. Thanks Tony for supplying extra! I was also little confused as each kit comes as 2 seperately mailed jiffy-bags!

                                                          In hindsight, I don't think there is much effect on the transmitter, as the first one I made seems OK and the harmonics are OK, but I think it is always best to balance out the pair as best as possible to minimise harmonic generation, and get the bias point about right for the correct distortion specs.
                                                          I guess when I have built the transmitter and keyed it up, I will discover the other transistor parameter mismatch.. (gm vatiation).
                                                          Hope this has been helpful, Happy building!
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