‰  NOW 25 WPM  ‰  TEXT IS FROM JANUARY 2014 QST  PAGE 46‰

SUPPLIES ONLY ABOUT 0R3 V P P.  MY SOLUTION USES AN EASY TO BUILD TWO
TRANSISTOR BUFFER AMPLIFIER FOLLOWED BY A 12 TOROIDAL VOLTAGE STEP UP
TRANSFORMER.  THAT COMBINATION BRINGS THE OUTPUT TO A NOMINAL 10 V P P
MEASURED ACROSS A 1 K TEST LOAD SEE THE QST IN DEPTH WEB PAGE.  THE BUFFER
AMPLIFIER THE BUFFER AMPLIFIER CIRCUIT SEEN IN FIGURE 4 WAS FOUND ON THE
N3ZI WEBSITE.  THOUGH THE OUTPUT OF THE BUFFER AMPLIFIER BEGINS TO ROLL OFF
ABOVE APPROXIMATELY 8 MHZ, THIS IS NOT A PROBLEM BECAUSE MOST VINTAGE
TRANSMITTERS USE A 3R5 MHZ OR 7 MHZ CRYSTAL OR VFO SIGNAL.  I BUILT MY
BUFFER AMP ON A SMALL PIECE OF VECTOR BOARD SEEN IN THE UPPER LEFT OF
FIGURE 3.  A RECEIVER INCREMENTAL TUNING RIT KEYING INVERTER IS ALSO ON
THAT BOARD.  WIRING STYLE IS NOT CRITICAL.  THE AMPLIFIER INCREASES THE
SYNTHESIZER OUTPUT TO ABOUT 5 V P P, WHICH MAY BE ENOUGH TO DRIVE MANY
VINTAGE TRANSMITTERS.  SOME TRANSMITTERS REQUIRE MORE DRIVE, SO CHECK YOUR
‰  END OF 25 WPM TEXT  ‰  QST DE W1AW  ƒ