‰  NOW 30 WPM  ‰
BOTH THE ATTENUATOR AND VOX CIRCUITRY ARE TAKEN DIRECTLY FROM K5OORS HF
PACKER AMPLIFIER PROJECT, WHICH IS A REFINEMENT OF THE 2001 ARRL HANDBOOK
DESIGN BY WA2EBY.  SEE K5OORS WEB SITE WWW. HFPROJECTS. COM FOR DETAILS.
IN ADDITION TO THE RF INPUT CIRCUITRY, THE CONTROL BOARD HAS A POWER FUSE,
AND THE DC AMPLIFIER FOR POWER CUTBACK.  WHEN THE PIC SWR METER DETECTS A
HIGH SWR CONDITION, IT DRIVES THE BASE OF Q4 THROUGH R9.  Q3 AND Q4 FORM A
DARLINGTON PAIR AMPLIFIER FOR ACTIVATING RELAY RY2 ON THE RELAY BOARD.  RY2
ADDS R8 THROUGH R10, ANOTHER P SECTION ATTENUATOR, IN SERIES WITH THE POWER
AMPLIFIER BOARDS INPUT.  R8 THROUGH R10 INTRODUCE 10 DB OF ATTENUATION,
CORRESPONDING TO A 10 1 REDUCTION IN DRIVE POWER.  THESE RESISTOR VALUES
ARE FIXED AND DO NOT DEPEND UPON THE TRANSCEIVER BEING USED.  LOOKING AT
THE CONTROL BOARD AGAIN, WHEN Q3 ACTIVATES THE RELAY FOR POWER CUTBACK IT
ALSO LIGHTS UP THE GREEN LED CIRCUIT.  Q2 ACTS AS AN INVERTER AND LIGHTS
THE RED LED WHEN Q3 IS OFF NO POWER CUTBACK.  THE GREEN AND RED LEDS CAN BE
‰  FROM PAGE 97  ‰
1,044 WWA Amateur Radio Transmitting Society W4CN 229 2 17 1,032 KY Lemhi
ARC AD7AN 158 2 4 1,032 ID Calaveras ARS WA6YGA 186 2 6 1,008 SJV Six Meter
‰  END OF 30 WPM TEXT  ‰  QST DE W1AW  ƒ