=  NOW 35 WPM  =  TEXT IS FROM AUGUST 2021  QST  PAGE 33 =

THIS CIRCUIT IS ALSO USEFUL WITH OTHER HOME BUILT RECEIVERS.  JAMES FORKIN,
WA3TFS MY SIMPLE HIGH FREQUENCY COMMUNICATIONS RECEIVER SEE THE LEAD PHOTO,
WHICH WAS FEATURED IN THE MAY 2020 ISSUE OF QST, HAS MANUAL GAIN CONTROLS
THAT MUST BE ADJUSTED WHEN THE SIGNAL LEVELS ARE OF VARYING SIGNAL
STRENGTH.  AN AUTOMATIC GAIN CONTROL AGC CIRCUIT WOULD KEEP THE AUDIO
OUTPUT AT A MORE CONSISTENT LEVEL ON WEAK SIGNALS AND ATTENUATE THE AUDIO
WHEN THE INCOMING SIGNAL IS AT A MUCH HIGHER LEVEL, THEREBY ELIMINATING THE
NEED TO READJUST GAIN MANUALLY.  THIS SIMPLE AGC CIRCUIT MEETS THAT NEED.
THE CIRCUIT RETAINS THE MANUAL GAIN CONTROL FUNCTION, AND ALSO PROVIDES AN
OUTPUT TO DRIVE AN S METER.  TWO DIFFERENT AGC OUTPUTS ARE PROVIDED.  ONE
INCREASES LEVEL WHEN A LOUD SIGNAL IS RECEIVED, AND A SECOND ONE DECREASES
LEVEL ON A LOUD SIGNAL.  THE SECOND OUTPUT IS USED WITH MY SIMPLE HIGH
FREQUENCY COMMUNICATIONS RECEIVER.  THE CIRCUIT THE DESIGN SEE FIGURE 1
USES A HANDFUL OF READILY AVAILABLE AND INEXPENSIVE THROUGH HOLE PARTS.  A
1R35 X 2R45 INCH PCB IS AVAILABLE AT.  YOU COULD ALSO WIRE IT ON PERF BOARD
MY BOARD LAYOUT IS ON THE QST IN DEPTH WEB PAGE AT ARRL. ORG/QST IN DEPTH.
PROVIDE A GOOD GROUND PLANE FOR BEST PERFORMANCE.  THREE POTENTIOMETERS
ALLOW FULL ADJUSTMENT OF AGC ACTION.  ONE IS USED TO SET THE POINT AT WHICH
AGC ACTION IS DESIRED.  A SECOND PROVIDES ADJUSTMENT TO CALIBRATE AN
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