‰  NOW 30 WPM  ‰  TEXT IS FROM AUGUST 2012 QST  PAGE 48‰

HIGH IMPEDANCE TUNING RANGE IS SIGNIFICANTLY BROADER THAN THE LOW IMPEDANCE
RANGE.  THE LOW IMPEDANCE LIMIT IS SPECIFIED AT 4 1 SWR.  I MEASURED THE
MFJ 998RT TUNER LOSSES USING THE 160 AND 80 METER SHORT ANTENNA SIMULATOR
CIRCUITS DESCRIBED EARLIER, AGAIN WITH APPROXIMATELY 10 OF REAL RESISTANCE
ADDED TO SIMULATE GROUND LOSSES.  THE MFJ998RT WAS ABLE TO MATCH A
SIMULATED 43 FOOT VERTICAL FOR 80 METERS AND A SIMULATED 90 FOOT ANTENNA
FOR 160 METERS WITH POWER LOSS LESS THAN 10 AND MINIMUM SWR OF 1R2 1 ON 80
AND 1R6 1 ON 160.  OPEN/SHORT CIRCUIT TESTING IDEALLY A TUNER SHOULD NOT BE
ABLE TO MATCH AN OPEN OR SHORT CIRCUIT LOAD.  IF IT DOES, THIS MEANS THAT
IT IS TUNING INTO ITS OWN INTERNAL LOSSES.  HOWEVER, NO ANTENNA TUNER IS
LOSSLESS DUE TO COMPONENTS WITH FINITE Q.  FROM PAST EXPERIENCE IVE FOUND
THAT MOST ANTENNA TUNERS MANUAL AND AUTOMATIC CAN FIND A MATCH ON ONE OR
MORE FREQUENCIES WHEN CONNECTED TO AN OPEN OR A SHORT.  IN THE ARRL LAB,
NEITHER TUNER COULD FIND A MATCH INTO AN OPEN CIRCUIT OR A SHORTED PL 259
CONNECTOR.  AT MY STATION, I FOUND SOME NOTEWORTHY SHORT CIRCUIT MATCH
OCCURRENCES.  WITH BOTH THE MFJ 994BRT AND MFJ998RT, ON 20 METERS I FOUND A
‰  END OF 30 WPM TEXT  ‰  QST DE W1AW  ƒ