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Re: [softrock40] Re: Too much RF power

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  • John Williams
    TO-220/TO-202 Aluminum Heat Sink *Model: *276-1368 ** ... -- John Williams KE5SSH - ham since 2007 WQKA523 - GMRS for family use on the farm TO-220/TO-202
    Message 1 of 8 , Feb 28, 2012
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      TO-220/TO-202 Aluminum Heat Sink
      Model: 276-1368


      On 2/28/2012 7:45 AM, John wrote:
       

      John,

      what is the part number of the heatsink that you are using?
      I installed a 1.5 inch fan but it puts too much noise on the DC line.

      John TI4/N0URE

      --- In softrock40@yahoogroups.com, John Greusel <greusel@...> wrote:
      >
      > Regarding heatsinks.
      > Radioshack has a great cast AL heatsink that is a perfect replacement for the stock one and I switched all my rigs to those when I started running digital modes.
      >
      > John
      > KC9OJV
      >
      >  
      >
      >
      >
      > ________________________________
      > From: Albert Gerheim <alpg49@...>
      > To: softrock40@yahoogroups.com
      > Sent: Monday, February 27, 2012 11:34 AM
      > Subject: Re: [softrock40] Re: Too much RF power
      >
      >
      >  
      > No, I haven't calibrated the audio.  My 10/12/15 build puts out 1Watt +/- 10mW on all bands, so I'm concerned about the overpower with the other unit. 
      >
      > I  theory, the output from the linear output stage should level off at 1Watt, no matter how hard you drive the audio, unless the waveshape is clipping and the excess power is in harmonics. 
      >
      > (Wondering out loud:) The 2N2222 driver stage has a partially bypassed emitter resistor, and the bypass cap and resistor (C22, R42) aren't installed for the 40/30/20 build.  This decreases the gain.  I wonder if the gain shouldn't be lowered even more.  It could be that the final is just being overdriven... although it's hard to get that much additional power out, even if you're going from a sine wave to a square wave.  (wondering silently) 
      >
      > I'm just going to throttle the audio down. 
      >
      >
      > On Mon, Feb 27, 2012 at 12:18 PM, John Williams <KE5SSH@...> wrote:
      >
      >
      > > 
      > >Al - Have you calibrated the output power of your sound system in PSDR on the first audio tab? 
      > >
      > >Mike - are you running WSPR in PSDR or direct using I/Q mode? If in
      > PSDR, same question on audio output calibration?
      > >
      > >John
      > >
      > >
      > >On 2/27/2012 10:51 AM, vbifyz wrote:
      > > 
      > >>I saw the same behavior in my 40/30/20 RXTX build.
      > >>I don't have test equipment to measure harmonics, but I
      > suspect that output above 1W would be distorted. I used it
      > for WSPR, so running it for 2 minutes at more than 1W
      > overheated the finals quickly.
      > >>Running at this much power for CW may be ok, just make
      > sure the finals don't overheat. The heatsink is not
      > designed for higher power.
      > >>
      > >>73, Mike
      > >>
      > >>--- In softrock40@yahoogroups.com, "alpg49" <alpg49@> wrote:
      > >>>
      > >>> I'm getting 2 or 3 watts out on my new 40/30/20 RXTX.
      > (... and I'm complaining :-) ) I'm throttling the Audio
      > down so I get 1 watt out. I'm measuring it on a QRP
      > wattmeter. I don't have a scope. Is this bad, and what can
      > possibly be causing it? I'm very sure of the cores types
      > and turns count on all the transformers.
      > >>>
      > >>>
      > >>>
      > >>> -Al Gerheim, K1QN
      > >>>
      > >>
      > >>
      > >
      > >-- John Williams KE5SSH - ham since 2007
      > WQKA523 - GMRS for family use on the farm
      >
      >
      > --
      > Al Gerheim
      > Adopt a Homeless Pet
      > http://www.petfinder.com
      >


      -- 
      
      John Williams
      
      KE5SSH - ham since 2007
      WQKA523 - GMRS for family use on the farm
      
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