‰  NOW 20 WPM  ‰  TEXT IS FROM DECEMBER 2008 QST  PAGES 33, 35 AND 74  ‰

CHANNEL TO MATCH THAT OF THE I CHANNEL A NECESSARY CONDITION FOR COMPLETE
SUPPRESSION OF UNWANTED SIDEBANDS.  U5 IS SET UP AS A FOUR STATE JOHNSON
COUNTER TO GENERATE THE FOUR SEQUENTIAL PULSES THAT DRIVE THE FOUR SWITCHES
IN U1 IN THE CORRECT ORDER.  U5 IN TURN IS CLOCKED FROM A VOLTAGE
COMPARATOR, U4, WHICH SQUARES UP THE 16 TO 18R04 MHZ SIGNAL FROM THE
EXTERNAL LOCAL OSCILLATOR COMING IN AT J3.  AT THE INPUT TO THE ANALOG
SWITCH ARRAY, A 4R0 TO 4R5 MHZ BAND PASS FILTER HELPS TO REJECT SPURIOUS
SIGNALS.  THE FILTER IS PRECEDED BY A TOROID TRANSFORMER TO MATCH THE
FILTER INPUT TO 50 AND BY A 50, 3 DB RESISTIVE PAD.  ADDING THE PAD
IMPROVED THE IMPEDANCE MATCH TO THE CONVERTER AND RESULTED IN A SMALL
‰  FROM PAGE 74  ‰
NWHC  Waller Co ARES KC8EO KD5HW 494 2 30 2,284 STX Riverside Radio
‰  END OF 20 WPM TEXT  ‰  QST DE W1AW  ƒ