‰  NOW 40 WPM  ‰  TEXT IS FROM DECEMBER 2006 QST  PAGES 29, 31 AND 92  ‰

EXCITER BLOCK DIAGRAM FIGURE 3 IS THE BLOCK DIAGRAM OF THE CIRCUITRY
ON THE PC BOARD.  IT IS A COMPLETE VXO SSB EXCITER ON A 2R5 X 3R8 INCH
CIRCUIT BOARD WITH 1 MW 0 DBM PEAK OUTPUT.  THE EXCITER USES THE PHASING
METHOD OF SSB GENERATION, WHICH MAKES IT EASY TO OPERATE ON DIFFERENT
FREQUENCIES.  IN A PHASING SSB EXCITER, TWO IDENTICAL SIGNALS WITH A 90
PHASE DIFFERENCE ARE GENERATED AND THEN COMBINED SO THAT ONE SIDEBAND ADDS
AND THE OTHER SUBTRACTS.  THIS METHOD IS COVERED IN DETAIL IN THE ARRL
HANDBOOK FOR RADIO COMMUNICATIONS.  THE SIGNAL QUALITY FROM THIS EXCITER IS
NOT MERELY ADEQUATE FOR THE HF AMATEUR BANDS IT IS EXCEPTIONAL.  RF
CIRCUITRY FREQUENCY GENERATOR THE FREQUENCY GENERATOR CONSISTS OF A VXO,
BUFFER AMPLIFIER AND QUADRATURE HYBRID.  IT HAS A LOT OF PARTS THREE
TRANSISTORS A VOLTAGE REGULATOR IC, A ZENER DIODE, FOUR TOROIDS AND MANY
RESISTORS AND CAPACITORS.  THERE ARE NO ADJUSTMENTS.  YOU JUST BUILD IT AND
IT WORKS.  THE FREQUENCY STABILITY IS BETTER THAN THAT OF MOST COMMERCIAL
RADIOS, EVEN WHEN PORTABLE.  VXO THERE ARE SIMPLER VXO CIRCUITS, BUT THIS
ONE IS THE BEST IVE EVER USED.  IT PROVIDES 0 DBM SINE WAVE OUTPUT, DRAWS 4
‰  FROM PAGE 92  ‰
70 NNJ KC2NFI 10 2 1 70 ENY WA5YNE 70 1 1 70 OK N0GRB 34 2 1 68 NE K9UTC 8
2 1 66 WI KI6BHB 33 2 1 66 ORG KD7HCU 13 1 1 63 WWA KP4JRS 6 1 1 62 PR
KC6WJA 5 2 1 60 LAX AD7HM 5 2 1 60 WWA KR0VER 10 1 1 60 CO KC8ZAP 5 2 1 60
‰  QST DE W1AW  ƒ

MA, AND HAS VIRTUALLY NO START UP DRIFT ABOUT 2 HZ AT 7 MHZ.  IT MAKES A
LOVELY KEYED CW GENERATOR TOO.  THE THREE RESISTOR ATTENUATOR BETWEEN THE
OUTPUT OF THE VXO AND INPUT OF THE BUFFER AMPLIFIER IS A CONVENIENT PLACE
TO INSERT A FREQUENCY MULTIPLIER OR EXTERNALLY GENERATED VFO.  JUST LEAVE
OFF THE TOP RESISTOR TO BREAK THE PATH.  NOTE THAT THE CRYSTAL AND VARIABLE
CAPACITOR ARE MOUNTED OFF THE PC BOARD.  FREQUENCY STABILITY IS DETERMINED
BY THE TEMPERATURE OF THE CRYSTAL.  I LIKE TO SLIP A FOAM PACKING BEAD OVER
THE CRYSTAL AND SUPPORT IT BY ITS LEADS BETWEEN THE PC BOARD AND VXO
CAPACITOR.  I USED A FRONT PANEL MOUNTED CRYSTAL SOCKET IN ONE PROTOTYPE
VERSION OF THIS EXCITER.  IT LOOKS VERY CLASSY, BUT NOISE PICKED UP BY THE
CRYSTAL BODY GETS INTO THE OSCILLATOR, AND THE SIGNAL RADIATED BY THE
CRYSTAL SOUNDS LIKE ONE WITH POOR CARRIER SUPPRESSION.  IF YOU USE A
CRYSTAL SOCKET, PUT IT INSIDE THE CASE OR BEHIND A SHIELD DOOR AS IN THE
OLD E. F. JOHNSON AND HEATHKIT TRANSMITTERS.  BUFFER THE BUFFER AMPLIFIER
‰  FROM PAGE 92  ‰
MI KC7KML 5 2 1 60 AZ WD4NIT 3 2 1 56 GA AA6EE 14 2 1 56 SDG W4SUL 28 2 1
56 NFL N1KN 27 2 1 54 CT KO6YG 4 1 1 54 SCV K4GHS 40 1 1 53 NC KB5DRJ 24 2

AMPLIFIER USES A COMMON GATE JFET.  THIS STAGE PROVIDES A BROADBAND
RESISTIVE TERMINATION TO THE MIXER RF PORT IQ SUMMING JUNCTION TO ISOLATE
IT FROM VARIATIONS IN IMPEDANCE AT THE EXCITER OUTPUT.  THE RF AMPLIFIER
HAS RELATIVELY LOW GAIN, GOOD HARMONIC S
‰  FROM PAGE 92  ‰
WA2CKP 7 2 1 14 NLI WA3LGG 3 2 1 12 EPA K1AZ 1 1 1 1 CT 2D WmHPouch BSA RC
‰  END OF 40 WPM TEXT  ‚