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PROJETO DE ANTENA
J DE VHF 144-148 MHZ THE J POLE ANTENNA THE J-POLE ANTENNA IS A VERY USEFUL
ANTENNA IN SITUATIONS WHERE A DC GROUND AND VERY LITTLE GAIN IS REQUIRED. THE
REASON THAT I LIKE THE ANTENNA IS THAT IT IS SIMPLE TO BUILD, STURDY, AND
VERY EASY TO TUNE. A FEW THINGS SHOULD BE DONE THOUGH IN ORDER TO PROLONG THE
LIFE OF THE ANTENNA. 1. CLEAN ALL COPPER FITTINGS WELL IN
ORDER TO INSURE A SOLID MECHANICAL AND ELECTRICAL CONNECTION. A POOR
CONNECTION CAN MEAN THAT THE ANTENNA WILL "SELF-DESTRUCT" IF IT IS
PUT OUT IN THE WEATHER AND WIND. 2. USE A STRANDED WIRE TO CONNECT THE
CENTER PIN TO THE SHORTER LEG ON ANTENNA. I HAVE USED SOLID WIRE IN THIS AREA
AND AFTER A SHORT AMOUNT OF TIME THE SOLDERED JOINT WILL CAUSE THE THE WIRE
TO BREAK FROM THE CONSTANT FLEXING OF THE PIPE IN THE WIND. THE STRANDED WIRE
WILL FLEX A SLIGHT BIT SO THAT IT WILL NOT JUST BREAK. 3. SOLDER AND BOLT THE COAX CONNECTOR TO
THE ANTENNA. BOTH OF THESE JOINTS WILL WORK TOGETHER TO HELD INSURE A STRONG
MECHANICAL AND ELECTRICAL CONNECTION. DO NOT USE A RADIO SHACK BRAND SO-239
CONNECT AS THEY ARE BASICALLY JUNK. THE CENTER INSULATIVE MATERIAL WILL NOT
WITHSTAND THE TEMPERATURE IN THE OUTSIDE AND WILL DEGRADE RAPIDLY. TIN AN
AMPENOL BRAND CONNECT WITH SOLDER AND THEN TIN THE PIPE. AFTER THIS HAS BEEN
DONE, BOLT THE CONNECTOR WITH THE TINNED PIECES FACING EACH OTHER AND THEN
WARM THE CONNECTOR WITH A SMALL TORCH. AFTER THE SOLDER HAS SET, IT WILL BE
ROCK SOLID. 4. DON'T SKIMP ON COST AS I HAVE ON SOME
ANTENNAS, BUY STAINLESS STEEL HARDWARE TO BOLT THE ANTENNA DOWN. IF YOU EVER
HAVE TO MOVE THE ANTENNA OR RETUNE THE ANTENNA YOU WILL THANK ME FOR THIS
HINT. 5. CAP THE PIPES AND PAINT THE ENTIRE
ANTENNA. PAINTING THE ANTENNA WITH A NONMETALLIC PAINT WILL ENSURE THAT THE
ANTENNA WILL LAST FOR YEARS TO COME. MAKE SURE TO DRILL A SMALL DRAIN HOLE IN
THE BOTTOM LEG OF THE ANTENNA SO THAT ANY CONDENSATION CAN DRAIN OUT. |