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RXTX Q2 driver heatsink hot

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  • Rick Meyer
    Tony, the TX part of my new RXTX seems to be working with the IQ test tones, but Q2, the TX driver transistor, has a heatsink that is getting almost too hot to
    Message 1 of 3 , Feb 1, 2007
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      Tony, the TX part of my new RXTX seems to be working with the IQ test
      tones, but Q2, the TX driver transistor, has a heatsink that is
      getting almost too hot to touch after a couple minutes at full power.
      Is this normal? Should this part have a little bigger heatsink? What
      should be the voltage at the emitter when there is no RF drive to mess
      with my voltmeter?

      Also I have the Ramsey 40 Meter power amplifier kit built and ready to
      connect to the RXTX, but it will only put out half its rated 20 watts
      of power with 1 watt drive from the RXTX. Can I feed the RXTX with
      13.6 volts instead of 12 to get a little more power out of the Ramsey
      PA? Would I need bigger heatsinks?
    • Tony Parks
      Hi Rick, The heatsink on the 2N2222A driver transistor runs pretty warm but so far that has not been a problem. The emitter voltage should be around 1.5 volts
      Message 2 of 3 , Feb 1, 2007
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        Hi Rick,
         
        The heatsink on the 2N2222A driver transistor runs pretty warm but so far that has not been a problem.  The emitter voltage should be around 1.5 volts with no RF drive.
         
        I would recomend staying within the 1 watt RF output to be sure the output of the RXTXv6.1 is meeting FCC requirements.
         
        73,
        Tony KB9YIG
         
        ----- Original Message -----
        Sent: Thursday, February 01, 2007 3:37 PM
        Subject: [softrock40] RXTX Q2 driver heatsink hot

        Tony, the TX part of my new RXTX seems to be working with the IQ test
        tones, but Q2, the TX driver transistor, has a heatsink that is
        getting almost too hot to touch after a couple minutes at full power.
        Is this normal? Should this part have a little bigger heatsink? What
        should be the voltage at the emitter when there is no RF drive to mess
        with my voltmeter?

        Also I have the Ramsey 40 Meter power amplifier kit built and ready to
        connect to the RXTX, but it will only put out half its rated 20 watts
        of power with 1 watt drive from the RXTX. Can I feed the RXTX with
        13.6 volts instead of 12 to get a little more power out of the Ramsey
        PA? Would I need bigger heatsinks?

      • FRANCIS CARCIA
        heat sink on a 2222, sounds over stressed. Tony Parks wrote: Hi Rick, The heatsink on the 2N2222A driver transistor runs pretty
        Message 3 of 3 , Feb 1, 2007
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          heat sink on a 2222, sounds over stressed.

          Tony Parks <raparks@...> wrote:
          Hi Rick,
           
          The heatsink on the 2N2222A driver transistor runs pretty warm but so far that has not been a problem.  The emitter voltage should be around 1.5 volts with no RF drive.
           
          I would recomend staying within the 1 watt RF output to be sure the output of the RXTXv6.1 is meeting FCC requirements.
           
          73,
          Tony KB9YIG
           
          ----- Original Message -----
          Sent: Thursday, February 01, 2007 3:37 PM
          Subject: [softrock40] RXTX Q2 driver heatsink hot

          Tony, the TX part of my new RXTX seems to be working with the IQ test
          tones, but Q2, the TX driver transistor, has a heatsink that is
          getting almost too hot to touch after a couple minutes at full power.
          Is this normal? Should this part have a little bigger heatsink? What
          should be the voltage at the emitter when there is no RF drive to mess
          with my voltmeter?

          Also I have the Ramsey 40 Meter power amplifier kit built and ready to
          connect to the RXTX, but it will only put out half its rated 20 watts
          of power with 1 watt drive from the RXTX. Can I feed the RXTX with
          13.6 volts instead of 12 to get a little more power out of the Ramsey
          PA? Would I need bigger heatsinks?


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