‰ NOW 40 WPM ‰ TEXT IS FROM JUNE 2015 QST PAGE 55‰ TUNER I HAVE TRIED. THIS EXPERIENCE REINFORCES THE MENTION IN THE MANUAL THAT IF THE TUNER DOESNT TUNE AS EXPECTED, TRY A DIFFERENT LENGTH OF FEED LINE. EVEN THOUGH A PROPERLY BALANCED FEED LINE DOESNT RADIATE, IT IS A BIG PART OF THE ANTENNA SYSTEM AND, FOR LOADS DIFFERENT THAN ITS Z0, IT ACTS AS AN IMPEDANCE TRANSFORMER. AFTER GETTING PAST THAT HURDLE, I WAS ABLE TO SET IN THE ADJUSTMENTS TO BE MEMORIZED WITHOUT DIFFICULTY USING MY ANTENNA ANALYZER AS AN RF SOURCE AND SWR UNIT IS INTERCONNECTED TO THE REMOTE TUNER VIA A 25 CONDUCTOR CABLE UP TO 130 FEET LONG LONGER DISTANCES REQUIRE HEAVIER WIRE. THE REMOTE TUNER FIGURES 2 AND 3 CONTAINS A BALANCED NETWORK WITH SHUNT CAPACITORS AT EACH END OF THE TWO INDUCTORS, ONE ON EACH SIDE. THE INDUCTORS, ADJUSTABLE TOGETHER IN 32 STEPS, AND THE INPUT CAPACITANCE, ADJUSTABLE IN 256 STEPS ARE SELECTED BY RELAYS SWITCHING IN FIXED ELEMENTS. THE ANTENNA SIDE CAPACITOR IS A ROTARY AIR DIELECTRIC VARIABLE CAPACITOR WITH A STEPPER MOTOR TO ADJUST IT IN 200 INCREMENTS. A GAP TYPE LIGHTNING ARRESTOR IS LOCATED AT THE ANTENNA TERMINALS. ON THE RADIO SIDE IS A 1 1 CHOKING BALUN THAT, WHEN TUNED, OPERATES WITH A 50 IMPEDANCE ON BOTH ENDS FOR MAXIMUM EFFICIENCY. THE OUTDOOR COAXIAL CONNECTOR IS A TYPE N SOCKET, A GOOD CHOICE FOR OUTDOOR USE. THE AT 615B REMINDS ME OF THE CLASSIC MOTORIZED BALANCED ANTENNA TUNER DESIGN PRESENTED BY RICHARD MEASURES, AG6K, IN QST YEARS AGO/. THE AT 615B IS CONFIGURED AS A BALANCED NETWORK, RATHER THAN BALANCED L NETWORK, TO ALLOW IT TO MATCH LOADS BOTH ABOVE AND BELOW 50. THE ORIGINAL MEASURES DESIGN HAS A SINGLE VARIABLE CAPACITOR ON THE OUTPUT A SEMIAUTOMATIC TUNER THE WAY THE AT 615B WORKS IS THAT THE OPERATOR FIRST MANUALLY PRELOADS OPTIMIZED TUNER SETTINGS CORRESPONDING TO THE TUNERS 85 FREQUENCY BINS. THE BINS ARE 20 KHZ WIDE ON 160 METERS, INCREASING TO 100 KHZ WIDE ON 10 METERS. I USED MY ANTENNA ANALYZER TO GENERATE THE SIGNALS AND MEASURE THE SWR AT THE CENTER FREQUENCY OF EACH OF THE FREQUENCY BINS. AFTER ADJUSTING THE AT 615B FOR MINIMUM SWR, I ENTERED THE SETTINGS INTO MEMORY AND ADDRESSED THE NEXT BIN. AFTER THE MEMORIES ARE ALL LOADED, THE CONTROL UNIT FUNCTION SWITCH IS MOVED FROM MANUAL TO AUTOMATIC AND THE MEMORY SWITCH IS SET FROM TUNE TO MEMORY. TRANSMITTING A SIGNAL TOWARD THE TUNER WITH THE FREQUENCY SENSOR IN LINE ALLOWS THE CONTROL HEAD TO MEASURE THE FREQUENCY. THE AT 615B THEN AUTOMATICALLY CHANGES THE TUNING TO THE MEMORIZED SETTING CORRESPONDING TO THE BIN CLOSEST TO THE MEASURED FREQUENCY. OVERVIEW THE TUNER AND CONTROLLER APPEAR TO BE WELL THOUGHT OUT AND WELL MADE. THE CONTROL UNIT FIGURE 1 INCLUDES A TWO LINE DISPLAY WITH THE TOP LINE SHOWING THE FREQUENCY BIN, EITHER SET MANUALLY WHILE MAKING ADJUSTMENTS, OR AS DETECTED BY THE RF SENSOR. THE SECOND LINE SHOWS THE POSITIONS OF THE THREE TUNING CONTROLS OF THE BALANCED NETWORK TUNING SYSTEM. THE CONTROLLER ALSO INCLUDES A KEYING LINE FOR THE POWER AMPLIFIER TO INHIBIT FULL POWER OPERATION WHILE THE AT 615B IS TUNING. THE CONTROL ‰ END OF 40 WPM TEXT ‰ QST DE W1AW ƒ