‰  NOW 30 WPM  ‰  TEXT IS FROM SEPTEMBER 2018  QST  PAGE 53 ‰

POPULAR CENTER FED ZEPP ANTENNA IS JUST AN 80 OR 40 METER DIPOLE USED ON
MULTIPLE BANDS AND FED BY LOW LOSS WINDOW LINE.  THE ACTUAL IMPEDANCE AT
THE BOTTOM OF THE WINDOW LINE GOING INTO THE BALUN WILL BE DIFFERENT ON
EACH BAND, SO THE TRANSFORMER WILL NOT BE MATCHED ON ANY BAND.  WITH LUCK,
A LENGTH OF LINE, AND A TRANSFORMATION RATIO, AN ANTENNA TUNER WILL BE ABLE
TO MATCH THE SYSTEM ON ANY BAND SEE FIGURE 1B.  THE POINT IS THAT THE
BALUNS ARE NOT ALWAYS CONNECTED TO THEIR DESIGN IMPEDANCE LOADS.  Q WOULD
YOU PROVIDE A SIMPLE EXPLANATION OF HOW A HIGH STANDING WAVE RATIO SWR AT
THE ANTENNA TERMINALS CAN CAUSE DAMAGE TO THE FINAL AMPLIFIER TRANSISTORS
OR TUBES IN A TRANSCEIVER OR AMPLIFIER?  IS THE EFFECT LIKE POWER FACTOR IN
ELECTRIC MOTORS, IN WHICH THE VOLTAGE AND CURRENT ARE OUT OF PHASE, AND CAN
EXCEED COMPONENT DESIGN?  A THE ACTIONS IN THE TWO TYPES OF DEVICES IS
QUITE DIFFERENT.  WITH AN SWR GREATER THAN 1 1, THE VOLTAGE OR THE CURRENT
ON THE TRANSMISSION LINE CAN BE UP TO DOUBLE THE VOLTAGE OR CURRENT THAT
YOU WOULD HAVE WITH A MATCHED LINE AT THE SAME POWER.  MEANWHILE, THE
MATCHED LINE WILL HAVE THE SAME VOLTAGE AND CURRENT ALONG THE LENGTH OF THE
‰  END OF 30 WPM TEXT  ‰  QST DE W1AW  ƒ