[1000mp] Re: Mark V Field Power Output Mod

[Thomas Giella KN4LF]

Joe,
  Your latest post amounts to "FLAMING" and you should be censored.

73,
Thomas F. Giella, KN4LF
Plant City, FL, USA
Grid Square EL87WX
Lat & Long 27 58 31 44N 82 09 51 98W

PODXS 070 PSK31 Club Member #349

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  ----- Original Message ----- 
  From: Joe Subich, K4IK 
  To: 'All about Yaesu 1000mp' ; 'Mike Schatzberg' 
  Sent: Friday, August 06, 2004 5:55 PM
  Subject: RE: [1000mp] Re: Mark V Field Power Output Mod



  Mike, 

  > I think the Toshiba 2SC2897 IMD Po curve speaks for itself, 
  > but a few extra words about it won't hurt.
  > 
  > There is a world of difference with IMD numbers ranging from 
  > -38db to -24db, the change from 60 watts to 100 watts.  The 
  > idle current was set to 100ma, in the test set up.
  > 
  > The factory apparently sets the radio at 50 watts output per 
  > transistor, or IMD numbers of approximately -35 db.  Therefore 
  > operation at 100 watts per transistor, degrades IMD performance, 
  > with this circuit configuration, by a factor of approximately 
  > 10 times.

  The Field is operating very close to the point of minimum IMD.  
  If you look at the test circuit, it does not contain much of 
  any output filtering - just an impedance matching "L" network.
  Since most practical lowpass filters  will have on the order 
  of .6 dB to 1 dB of insertion loss, I'd estimate the push-pull 
  pair of transistors in the Field is actually generating about 
  115 watts at the collector to make 100 Watts at the output 
  connector.  That would set the IMD at around -36 or -37 dB.  
  The output of the radio can't be controlled any more closely 
  than that. 

  I stick by my original comment, anyone who would run a Field 
  at 150 or 200 watts is the same kind of immature, sick person 
  who would illegally "hotrod" a CB radio.  BTW, Texas Star (one 
  of the biggest trash peddlers) uses four 2SC2897s in their 350 
  Watt "export" amplifier - need I say more? 

  73, 

     ... Joe, K4IK 
    

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