‰  NOW 25 WPM  ‰  TEXT IS FROM JANUARY 2015 QST  PAGE 99‰

MANIPULATION DIFFERENTLY IN THOSE DAYS AND WERE NOT TALKING ABOUT JUST
KNOBS AND CRYSTALS.  MOST TRANSMITTERS GENERATED SIGNALS AT ONE OR MORE OF
THE HARMONICALLY RELATED AMATEUR BANDS BY STARTING WITH A FUNDAMENTAL
FREQUENCY AND THEN USING MULTIPLIER STAGES TO DRIVE THE FINAL AMPLIFIER AT
THE DESIRED FREQUENCY.  IN CONTRAST, IN SUPERHET RECEIVERS, THE INCOMING
SIGNAL WAS MIXED OR HETERODYNED WITH A LOCAL OSCILLATOR OPERATING ON A
FREQUENCY OUTSIDE THE DESIRED BAND.  THIS CREATED A SUM OR DIFFERENCE KNOWN
AS THE INTERMEDIATE FREQUENCY, OR IF, THAT WOULD BE AMPLIFIED, DETECTED,
AND PROCESSED TO PRODUCE AN AUDIBLE RESULT.  THE LOCAL OSCILLATOR IN THE
RECEIVER, AND THE OSCILLATOR IN THE TRANSMITTER, THEREFORE, WERE ON
DIFFERENT FREQUENCIES BECAUSE THEY HAD DIFFERENT DESIGN GOALS.  AS A
RESULT, THE RECEIVER OSCILLATOR COULDNT WORK IN THE TRANSMITTER CHAIN, AND
VICE VERSA.  THE ADVENT OF SINGLE SIDEBAND SSB PROVIDED A SOLUTION.  IN THE
‰  END OF 25 WPM TEXT  ‰  QST DE W1AW  ƒ