‰  NOW 30 WPM  ‰   TEXT IS FROM SEPTEMBER 2013 QST  PAGE 36‰

COMMON NODE INPUT IMPEDANCE OF 51 J29 FOR THE FINISHED ARRAY.  THE DETAILS
OF THE TRANSFORMERS ARE SUMMARIZED IN TABLE 4.  TABLE 4 SHOWS THAT MORE
PRIMARY TURNS WERE REQUIRED THAN HAD BEEN ANTICIPATED BY A SIMPLE VIEW OF
TRANSFORMER DESIGN.  THIS COULD BE DUE TO WINDING END EFFECTS WHERE THE END
TURNS COUPLED INEFFICIENTLY TO THE CORE.  CAREFUL ADJUSTMENT OF THE NUMBER
OF TURNS WAS MADE AS MEASUREMENTS CHECKED THE OPEN CIRCUIT VOLTAGE RATIO.
SMALL ERRORS IN ACHIEVING THE SPECIFICATION ARE DUE TO AN INABILITY TO
REALIZE FRACTIONAL TURNS.  THE ATTENUATION OF EACH TRANSFORMER WAS ABOUT
1R2 DB, EQUIVALENT TO A TRANSFORMATION EFFICIENCY OF 76.  THE REALIZATION
OF THE TRANSFORMERS REQUIRED GREAT CARE, BUT THERE IS CERTAINLY SCOPE FOR
FURTHER IMPROVEMENT HERE.  THE DIRECTION CONTROL SYSTEM IN ORDER TO DIRECT
THE BEAM TO ONE OF THE FOUR DIAGONAL DIRECTIONS THE FEEDS TO THE ELEMENTS
HAVE TO BE REROUTED, IDEALLY UNDER ELECTRICAL CONTROL.  FIGURE 6 SHOWS THE
TOPOLOGY OF A SWITCHING MATRIX FOR ROUTING THE THREE POSSIBLE PHASE SHIFTED
FEEDS TO THE APPROPRIATE ELEMENTS FOR A PARTICULAR DIRECTION OF FIRE.  THE
SWITCHES USED WERE RF LATCHING REED RELAYS WITH A CURRENT CARRYING RATING
‰  END OF 30 WPM TEXT  ‰  QST DE W1AW  ƒ