‰  NOW 25 WPM  ‰  TEXT IS FROM DECEMBER 2006 QST  PAGES 31, 33 AND 92  ‰
SWITCH MAY BE REPLACED BY A PAIR OF JUMPERS ON THE PC BOARD.  IF THAT
RESULTS IN THE WRONG SIDEBAND, REVERSE THE CONNECTIONS BETWEEN THE AUDIO
DRIVER TRANSISTORS AND MIXERS.  CLASS A AUDIO DRIVERS THE I AND Q AUDIO
DRIVERS ARE EMITTER FOLLOWERS DIRECTLY DRIVEN BY THE AMPLITUDE AND PHASE
TRIM OP AMPS.  EMITTER FOLLOWERS WERE USED SUCCESSFULLY IN THE ORIGINAL T2
AND WORK WELL.  AN EMITTER FOLLOWER CAN ONLY SOURCE CURRENT, SO IT MUST BE
BIASED WITH MORE THAN THE NEGATIVE PEAK CURRENT REQUIRED BY THE MIXER IF
PORTS.  SEE THE DISCUSSION ON PAGE 2R11 OF EMRFD, AND THE OUTPUT WAVEFORMS
IN FIGURES 2R32 AND 2R33.  Q1 AND Q2 EACH HAVE A QUIESCENT CURRENT OF MORE
THAN 10 MA.  FOR A RECEIVE APPLICATION, I WOULD HAVE USED A DIFFERENT
APPROACH TO SAVE OPERATING CURRENT, BUT SINCE THE EXCITER DRAWS ONLY A
FRACTION OF THE TOTAL TRANSMITTER CURRENT IN MOST APPLICATIONS AND IS
‰  FROM PAGE 92  ‰
187 2 8 374 WWA Moultrie AR Klub W9BIL 91 2 7 360 IL K1NT 86 2 2 298 IN
‰  END OF 25 WPM TEXT  ‰  QST DE W1AW  ƒ