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Re: [softrock40] Re: V6 RXTX analysis of TX chain

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  • Bill Dumke
    I know. Just had to replace the cooling fan in my PC, think I might use that heat sink with some modification. Just pop the fan off. Bill WA9PWR
    Message 1 of 80 , Nov 28, 2006
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      I know. Just had to replace the cooling fan in my PC, think I might use
      that heat sink with some modification. Just pop the fan off.

      Bill WA9PWR

      KD5NWA wrote:
      >
      > Bill Dumke wrote:
      > > Thanks, Cecil, for the good critical analysis of the 2N5590 circuit. I
      > > just ordered it from RF Parts along with a Motorola 2N3553 to use in
      > > place of the 2N3866. From what I have seen in the list I think they
      > > will make a great lineup for the transmitter. Already have the LT6231
      > > ultra low noise op amps to use in the receiver portion.
      > >
      > > Bill WA9PWR
      > >
      > > KD5NWA wrote:
      > >>
      > >> Civil behavior has left this discussion, and so will I.
      > >>
      > >> FRANCIS CARCIA wrote:
      > >> > bull puckie
      > >> >
      > >> > */KD5NWA <kd5nwa@... <mailto:kd5nwa%40sbcglobal.net>
      > <mailto:kd5nwa%40sbcglobal.net>>/* wrote:
      > >> >
      > >> > tom_iphi wrote:
      > >> > > Sure, but this guy is not doing push-pull!
      > >> > > This Harry Lythall - SM0VPO claims, that at 12V and
      > Ic,idle=250mA he
      > >> > > can get a linear 4W RF out of a single transistor! And he's doing Z
      > >> > > up-transformation. So the transistor current should even be higher!
      > >> > > ???
      > >> > > 73, Tom
      > >> >
      > >> > SNIP
      > >> >
      > >> > I notice that the amplifier is not advertised for any particular
      > power
      > >> > level, it's just a "HF BANDS QRP LINEAR AMPLIFIER"
      > >> >
      > >> > When talking about heat, and SWR he states that it can run at 4 watts
      > >> > without overheating, and it can handle from an open load to a
      > short for
      > >> > a load.
      > >> >
      > >> > When adjusting the bias he speaks of 250 mA but he doesn't state the
      > >> > power, he does admonish you that you may need to adjust the bias.
      > >> >
      > >> > My suggestion is, if you don't like it, don't use it, if however you
      > >> > chose to use it set it to 250 mA and see what happens with
      > distortion,
      > >> > if it's not good enough crank it up a bit. I have no doubt that at 4
      > >> > watts you will need to increase the bias current, but as it is it
      > will
      > >> > do at least a Watt (peak) out.
      > >> >
      > >> > The device he picked is very tough and can do over 10 watts output if
      > >> > your impedance matching loads it properly. To me it seems that the
      > >> > output transformer is set for more than a couple of Watts out but
      > >> > rather
      > >> > 10 or more watts of input. He is using a higher power design that he
      > >> > got
      > >> > in some application notebook and is cranking down the bias
      > because you
      > >> > can for lower power.
      > >> >
      > >> > Feel free to re-adjust the bias and drive, that transistor is quite
      > >> > rugged and can handle a lot more than 250 mA and has a lot of heat
      > >> > dissipation to spare. I already stated that I don't feel comfortable
      > >> > with the Bias scheme, too much opportunity for thermal runaway at
      > high
      > >> > temperatures.
      > >> >
      > >> > --
      > >> >
      > >> > Cecil
      > >> > KD5NWA
      > >> > www.qrpradio.com www.hpsdr.com
      > >> >
      > >> > "Sacred Cows make the best Hamburger!" Don Seglio Batuna
      > >> >
      >
      > Bolt on a decent heat sink to keep the transistor cool, and you should
      > get at least 3 to 4 watts.
      > --
      >
      > Cecil
      > KD5NWA
      > www.qrpradio.com www.hpsdr.com
      >
      > "Sacred Cows make the best Hamburger!" Don Seglio Batuna
      >
      >
    • Bill Dumke
      I know. Just had to replace the cooling fan in my PC, think I might use that heat sink with some modification. Just pop the fan off. Bill WA9PWR
      Message 80 of 80 , Nov 28, 2006
      • 0 Attachment
        I know. Just had to replace the cooling fan in my PC, think I might use
        that heat sink with some modification. Just pop the fan off.

        Bill WA9PWR

        KD5NWA wrote:
        >
        > Bill Dumke wrote:
        > > Thanks, Cecil, for the good critical analysis of the 2N5590 circuit. I
        > > just ordered it from RF Parts along with a Motorola 2N3553 to use in
        > > place of the 2N3866. From what I have seen in the list I think they
        > > will make a great lineup for the transmitter. Already have the LT6231
        > > ultra low noise op amps to use in the receiver portion.
        > >
        > > Bill WA9PWR
        > >
        > > KD5NWA wrote:
        > >>
        > >> Civil behavior has left this discussion, and so will I.
        > >>
        > >> FRANCIS CARCIA wrote:
        > >> > bull puckie
        > >> >
        > >> > */KD5NWA <kd5nwa@... <mailto:kd5nwa%40sbcglobal.net>
        > <mailto:kd5nwa%40sbcglobal.net>>/* wrote:
        > >> >
        > >> > tom_iphi wrote:
        > >> > > Sure, but this guy is not doing push-pull!
        > >> > > This Harry Lythall - SM0VPO claims, that at 12V and
        > Ic,idle=250mA he
        > >> > > can get a linear 4W RF out of a single transistor! And he's doing Z
        > >> > > up-transformation. So the transistor current should even be higher!
        > >> > > ???
        > >> > > 73, Tom
        > >> >
        > >> > SNIP
        > >> >
        > >> > I notice that the amplifier is not advertised for any particular
        > power
        > >> > level, it's just a "HF BANDS QRP LINEAR AMPLIFIER"
        > >> >
        > >> > When talking about heat, and SWR he states that it can run at 4 watts
        > >> > without overheating, and it can handle from an open load to a
        > short for
        > >> > a load.
        > >> >
        > >> > When adjusting the bias he speaks of 250 mA but he doesn't state the
        > >> > power, he does admonish you that you may need to adjust the bias.
        > >> >
        > >> > My suggestion is, if you don't like it, don't use it, if however you
        > >> > chose to use it set it to 250 mA and see what happens with
        > distortion,
        > >> > if it's not good enough crank it up a bit. I have no doubt that at 4
        > >> > watts you will need to increase the bias current, but as it is it
        > will
        > >> > do at least a Watt (peak) out.
        > >> >
        > >> > The device he picked is very tough and can do over 10 watts output if
        > >> > your impedance matching loads it properly. To me it seems that the
        > >> > output transformer is set for more than a couple of Watts out but
        > >> > rather
        > >> > 10 or more watts of input. He is using a higher power design that he
        > >> > got
        > >> > in some application notebook and is cranking down the bias
        > because you
        > >> > can for lower power.
        > >> >
        > >> > Feel free to re-adjust the bias and drive, that transistor is quite
        > >> > rugged and can handle a lot more than 250 mA and has a lot of heat
        > >> > dissipation to spare. I already stated that I don't feel comfortable
        > >> > with the Bias scheme, too much opportunity for thermal runaway at
        > high
        > >> > temperatures.
        > >> >
        > >> > --
        > >> >
        > >> > Cecil
        > >> > KD5NWA
        > >> > www.qrpradio.com www.hpsdr.com
        > >> >
        > >> > "Sacred Cows make the best Hamburger!" Don Seglio Batuna
        > >> >
        >
        > Bolt on a decent heat sink to keep the transistor cool, and you should
        > get at least 3 to 4 watts.
        > --
        >
        > Cecil
        > KD5NWA
        > www.qrpradio.com www.hpsdr.com
        >
        > "Sacred Cows make the best Hamburger!" Don Seglio Batuna
        >
        >
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