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Re: [Kenwood_TS50] TS50 Parasitics

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  • Bill
    Remy, I am sure now that the problem will be a leaky switch diode on one of the little filter boards that are oriented vertically, or more likely in the signal
    Message 1 of 7 , Apr 1, 2003
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      Remy, I am sure now that the problem will be a leaky switch diode on one of the little filter boards that are oriented vertically, or more likely in the signal path to or from the filters.
      bill
      Remy Jentges <rjentges@...> wrote:Dear Bill,
      Many thanks for your support, your thoughts are most welcome, as I am still
      'dry' on the subject.
      I disconnected the early stages at predriver feed point already. The PA
      section was found stable. I did not try yet to 'sollicit' oscillations by
      touching the predriver input, will do it as the next test.
      I noticed that oscillations need a little drive to start.
      I have in mind to feed the PA section with another transceiver, with
      variable power ouput through a 30dB power atten.
      My bench is busy for the time being with a TS-940 fixed at 90%, main trouble
      was in the PLL, a difficult one !
      I will take the TS-50 next with the hope that in the mean time I would have
      received the PA section active components.
      40 years in radio, I never gave up ! (and always succeeded !)
      73, Remy F6ABJ.





      ----- Original Message -----
      From: "Bill" <coorsbill@...>
      To: <Kenwood_TS50@yahoogroups.com>
      Sent: Monday, March 31, 2003 3:37 PM
      Subject: Re: [Kenwood_TS50] TS50 Parasitics


      >
      > Dear Remy,
      > It sure sounds like an instability in an early stage. The transistors used
      in the TS-50 final stage are notoriously stable. I have never seen them take
      off!
      > I am thinking that perhaps there is a leaky T/R switching diode that is
      allowing the transmitter to "talk back" to an earlier stage.
      > Let me digest this for a day or two and see if I can come up with some
      ideas for you.
      > I think your friend's advice to start with the earlier, that is, less
      expensive, stages is good.
      > Locate the input coax for the PA section, and disconnect it. See if the
      instability is still there. You can trigger the instability by simply
      touching the center conductor of the INPUT coax (not the output, you could
      get burned!!!). If the instability is in the PA section (pre-driver, drivers
      or PAs), it will take off and it will be obvious. If the PA section proves
      to be stable with the input disconnected, the problem (I hope) is in the
      earlier stages that are shared.
      > I seem to remember having a problem with a steering diode on one of the
      little, vertically-mounted filter boards on the main unit a few years ago.
      > bill
      > Remy Jentges <rjentges@...> wrote:Dear TS-50er
      > I am still with my PA parasitics problem...
      > Parasitics appears in all bands, all powers, phenomenon starts almost
      > instantly in all modes.
      > For a little while I thought I had found the reason, parasicts disappeared
      > for a solid 14V supply. Now parasitics are on again, what ever supply
      > voltage is.
      > When the PA is oscillating, it gives a close to 200W power output. The
      power
      > control loop does not work as a consequence of the self oscillating.
      > I gave a thorough testing and double check to what ever I could think at :
      > ground loops, poor solder join of PA transistors, burned/open
      capacitors...
      > Everything is just perfect.
      > I called a good friend of mine, head of a well known hamradio workshop
      here
      > in france, he said that he has seen this in few instances, and the cure
      was
      > to change driver and or PA transistors, starting with driver and predriver
      > first.
      > Unless someone has the 'idea of the day', I am prepared to begin a PA
      > surgical intervention as soon as I get the (expensive) components I
      already
      > ordered.
      > In any case, I will keep the TS-50 family posted of the outcome.
      > 73, Remy F6ABJ.
      >
      >
      >
      >
      >
      > Everything
      > ----- Original Message -----
      > From: "Remy Jentges" <rjentges@...>
      > To: <Kenwood_TS50@yahoogroups.com>
      > Sent: Sunday, March 09, 2003 7:00 AM
      > Subject: [Kenwood_TS50] TS50 Parasitics
      >
      >
      > > Hi there,
      > > Happy owner of a TS-50 since the early days, I enjoyed it in many trips
      > > mainly in Africa, sometimes in /mm. Now it suffers of PA parasitic
      > > oscillations that I was not able to fix yet.
      > > Parasitics started to show up from time to time, very seldom in the
      past.
      > Now it is on constantly.
      > > May be someone in the group has had the same experience and found the
      cure
      > ?
      > > 73, Remy F6ABJ.
      > >
      > >
      > >
      > >
      > > [Non-text portions of this message have been removed]
      > >
      > >
      > >
      > >
      > > To unsubscribe from this group, send an email to:
      > > Kenwood_TS50-unsubscribe@yahoogroups.com
      > >
      > >
      > >
      > > Your use of Yahoo! Groups is subject to
      http://docs.yahoo.com/info/terms/
      > >
      > >
      >
      >
      > Yahoo! Groups SponsorADVERTISEMENT
      >
      > To unsubscribe from this group, send an email to:
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      >
      >
      >
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      >
      >
      >
      > see our website www.amateur-repairs.com
      >
      >
      >
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      > [Non-text portions of this message have been removed]
      >
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      >


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    • Remy Jentges
      Bill, Many thanks for the follow up. I am in a business trip, next step will be to investigate the way you suggest upon return. 73 Remy F6ABJ. ... From: Bill
      Message 2 of 7 , Apr 1, 2003
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        Bill,
        Many thanks for the follow up. I am in a business trip, next step will be to
        investigate the way you suggest upon return.
        73 Remy F6ABJ.

        ----- Original Message -----
        From: "Bill" <coorsbill@...>
        To: <Kenwood_TS50@yahoogroups.com>
        Sent: Tuesday, April 01, 2003 6:21 PM
        Subject: Re: [Kenwood_TS50] TS50 Parasitics


        >
        > Remy, I am sure now that the problem will be a leaky switch diode on one
        of the little filter boards that are oriented vertically, or more likely in
        the signal path to or from the filters.
        > bill
        > Remy Jentges <rjentges@...> wrote:Dear Bill,
        > Many thanks for your support, your thoughts are most welcome, as I am
        still
        > 'dry' on the subject.
        > I disconnected the early stages at predriver feed point already. The PA
        > section was found stable. I did not try yet to 'sollicit' oscillations by
        > touching the predriver input, will do it as the next test.
        > I noticed that oscillations need a little drive to start.
        > I have in mind to feed the PA section with another transceiver, with
        > variable power ouput through a 30dB power atten.
        > My bench is busy for the time being with a TS-940 fixed at 90%, main
        trouble
        > was in the PLL, a difficult one !
        > I will take the TS-50 next with the hope that in the mean time I would
        have
        > received the PA section active components.
        > 40 years in radio, I never gave up ! (and always succeeded !)
        > 73, Remy F6ABJ.
        >
        >
        >
        >
        >
        > ----- Original Message -----
        > From: "Bill" <coorsbill@...>
        > To: <Kenwood_TS50@yahoogroups.com>
        > Sent: Monday, March 31, 2003 3:37 PM
        > Subject: Re: [Kenwood_TS50] TS50 Parasitics
        >
        >
        > >
        > > Dear Remy,
        > > It sure sounds like an instability in an early stage. The transistors
        used
        > in the TS-50 final stage are notoriously stable. I have never seen them
        take
        > off!
        > > I am thinking that perhaps there is a leaky T/R switching diode that is
        > allowing the transmitter to "talk back" to an earlier stage.
        > > Let me digest this for a day or two and see if I can come up with some
        > ideas for you.
        > > I think your friend's advice to start with the earlier, that is, less
        > expensive, stages is good.
        > > Locate the input coax for the PA section, and disconnect it. See if the
        > instability is still there. You can trigger the instability by simply
        > touching the center conductor of the INPUT coax (not the output, you could
        > get burned!!!). If the instability is in the PA section (pre-driver,
        drivers
        > or PAs), it will take off and it will be obvious. If the PA section proves
        > to be stable with the input disconnected, the problem (I hope) is in the
        > earlier stages that are shared.
        > > I seem to remember having a problem with a steering diode on one of the
        > little, vertically-mounted filter boards on the main unit a few years ago.
        > > bill
        > > Remy Jentges <rjentges@...> wrote:Dear TS-50er
        > > I am still with my PA parasitics problem...
        > > Parasitics appears in all bands, all powers, phenomenon starts almost
        > > instantly in all modes.
        > > For a little while I thought I had found the reason, parasicts
        disappeared
        > > for a solid 14V supply. Now parasitics are on again, what ever supply
        > > voltage is.
        > > When the PA is oscillating, it gives a close to 200W power output. The
        > power
        > > control loop does not work as a consequence of the self oscillating.
        > > I gave a thorough testing and double check to what ever I could think at
        :
        > > ground loops, poor solder join of PA transistors, burned/open
        > capacitors...
        > > Everything is just perfect.
        > > I called a good friend of mine, head of a well known hamradio workshop
        > here
        > > in france, he said that he has seen this in few instances, and the cure
        > was
        > > to change driver and or PA transistors, starting with driver and
        predriver
        > > first.
        > > Unless someone has the 'idea of the day', I am prepared to begin a PA
        > > surgical intervention as soon as I get the (expensive) components I
        > already
        > > ordered.
        > > In any case, I will keep the TS-50 family posted of the outcome.
        > > 73, Remy F6ABJ.
        > >
        > >
        > >
        > >
        > >
        > > Everything
        > > ----- Original Message -----
        > > From: "Remy Jentges" <rjentges@...>
        > > To: <Kenwood_TS50@yahoogroups.com>
        > > Sent: Sunday, March 09, 2003 7:00 AM
        > > Subject: [Kenwood_TS50] TS50 Parasitics
        > >
        > >
        > > > Hi there,
        > > > Happy owner of a TS-50 since the early days, I enjoyed it in many
        trips
        > > > mainly in Africa, sometimes in /mm. Now it suffers of PA parasitic
        > > > oscillations that I was not able to fix yet.
        > > > Parasitics started to show up from time to time, very seldom in the
        > past.
        > > Now it is on constantly.
        > > > May be someone in the group has had the same experience and found the
        > cure
        > > ?
        > > > 73, Remy F6ABJ.
        > > >
        > > >
        > > >
        > > >
        > > > [Non-text portions of this message have been removed]
        > > >
        > > >
        > > >
        > > >
        > > > To unsubscribe from this group, send an email to:
        > > > Kenwood_TS50-unsubscribe@yahoogroups.com
        > > >
        > > >
        > > >
        > > > Your use of Yahoo! Groups is subject to
        > http://docs.yahoo.com/info/terms/
        > > >
        > > >
        > >
        > >
        > > Yahoo! Groups SponsorADVERTISEMENT
        > >
        > > To unsubscribe from this group, send an email to:
        > > Kenwood_TS50-unsubscribe@yahoogroups.com
        > >
        > >
        > >
        > > Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
        > >
        > >
        > >
        > > see our website www.amateur-repairs.com
        > >
        > >
        > >
        > > ---------------------------------
        > > Do you Yahoo!?
        > > Yahoo! Platinum - Watch CBS' NCAA March Madness, live on your desktop!
        > >
        > > [Non-text portions of this message have been removed]
        > >
        > >
        > >
        > > To unsubscribe from this group, send an email to:
        > > Kenwood_TS50-unsubscribe@yahoogroups.com
        > >
        > >
        > >
        > > Your use of Yahoo! Groups is subject to
        http://docs.yahoo.com/info/terms/
        > >
        > >
        >
        >
        > Yahoo! Groups SponsorADVERTISEMENT
        >
        > To unsubscribe from this group, send an email to:
        > Kenwood_TS50-unsubscribe@yahoogroups.com
        >
        >
        >
        > Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
        >
        >
        >
        > see our website www.amateur-repairs.com
        >
        >
        >
        > ---------------------------------
        > Do you Yahoo!?
        > Yahoo! Tax Center - File online, calculators, forms, and more
        >
        > [Non-text portions of this message have been removed]
        >
        >
        >
        > To unsubscribe from this group, send an email to:
        > Kenwood_TS50-unsubscribe@yahoogroups.com
        >
        >
        >
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        >
        >
        >
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