=  NOW 40 WPM  = RELAY, BUT IM AFRAID TO USE IT, BECAUSE THE RELAY
DOES NOT GROUND THE RECEIVER WHEN TRANSMITTING.  AM I SAFE USING
EITHER ONE OF THE TWO RELAYS, OR SHOULD I ACQUIRE A TUBE TYPE
RECEIVER?  A ONE PROBLEM IS THAT NO ONE IS SURE ABOUT THE SAFE INPUT
LEVEL OF MODERN GEAR, BECAUSE THE MANUFACTURERS DONT SPECIFY,
ALTHOUGH THEY MIGHT ANSWER IF ASKED ABOUT A PARTICULAR TRANSCEIVER
ON A PARTICULAR BAND.  WE CAN BELIEVE THAT AN INPUT OF 10 DBM IS
SAFE, BECAUSE DURING QST PRODUCT REVI JOEL R. HALLAS, W1ZR, W1ZR
ARRL. ORG  THE DOCTOR IS IN SOME ANTENNAS NEED LOW RESISTANCE
CONNECTIONS TO BE EFFECTIVE Q A FRIEND AND I HAVE GOTTEN VERY
INTERESTED IN BUILDING SMALL TRANSMITTING HF LOOP ANTENNAS.  IS
THERE ANYTHING IN THE AMATEUR LITERATURE THAT DISCUSSES HOW TO
IMPLEMENT VERY LOW RESISTANCE M LEVEL RF CONNECTIONS?  I AM
REASONABLY UP TO DATE ON WHAT HAS BEEN PUBLISHED IN AMATEUR RADIO
PERIODICALS ON SMALL LOOP ANTENNAS GOING BACK TO TED HARTS, W5QJR,
ARTICLE, SMALL, HIGH EFFICIENCY LOOP ANTENNAS, IN THE JUNE 1986
ISSUE OF QST BUT I DONT TRULY UNDERSTAND WHAT IS NEEDED FOR JOINTS
THAT DONT TURN THE HIGH RF CURRENT INTO HEAT.  A FIRST, THANK YOU TO
SENIOR LAB ENGINEER ZACK LAU, W1VT, FOR HIS COMMENTS ON THIS.  THE
LOSS COULD BE INDIRECTLY MEASURED BY CALCULATING THE BANDWIDTH OF
THE LOOP THE NARROWER THE BANDWIDTH, THE BETTER.  ZACKS GUESS IS
THAT THE BEST APPROACH IS TO BRAZE EVERYTHING ONCE, THEN CAREFULLY
SAND AND POLISH ALL JOINTS TO A MIRROR LIKE SURFACE.  ANOTHER
PARAMETER IS THE NEEDED DURATION OF THE CONNECTION, BECAUSE MOST
CONNECTION ARRANGEMENTS DEGRADE OVER TIME.  SOME MECHANICAL
CONNECTIONS THAT DEGRADE DUE TO OXIDATION CAN HAVE THEIR RESISTANCE
GROWTH DELAYED BY A COMBINATION OF CONDUCTIVE ANTICORROSION GREASE
ON THE SURFACE AND COVERING THE JOINT WITH SOMETHING THAT KEEPS NEW
OXYGEN AWAY.  SOME ANTENNA MATERIALS, PARTICULARLY ALUMINUM, LOSE
THEIR CONNECTIVITY DUE TO SHRINKING UNDER PRESSURE.  IN THE 1950S,
THE WIRE UNDER SCREW TERMINALS GOT THINNER OVER TIME AND THE
RESISTANCE WENT UP, RESULTING IN HOUSE FIRES.  THIS WAS ALSO A
PROBLEM WITH RADIO EQUIPMENT THAT USED ALUMINUM RIVETS TO ATTACH
THINGS, SUCH AS TUBE SOCKETS, TO STEEL CHASSIS.  ALMOST ALL RADIOS
FROM THOSE TIMES THAT I HAVE RESTORED HAD DC RESISTANCES BETWEEN THE
SOCKET AND ITS GROUND CONNECTIONS, AND THE ACTUAL CHASSIS GROUND, IN
THE SINGLE DIGIT OHMS RANGE PERFECT FOR CAUSING ALL MANNER OF
PROBLEMS.  BRAZING OR WELDING MAY BE THE BEST OPTION.   SOLDERING IS
CLOSE, BUT DIFFICULT FOR SOME METALS, AND UNPROTECTED JOINTS DEGRADE
WITH EXPOSURE OVER TIME.  ANY MECHANICAL CONNECTION INVOLVING
ALUMINUM BEAM CLAMPS OR OTHER JOINTS SHOULD BE TIGHTENED
PERIODICALLY AND APPROPRIATE COMPOUNDS APPLIED TO ALL MECHANICAL
JOINTS, AS WELL AS ELECTRICAL INSULATING MATERIAL TO PROTECT THE
CONNECTIONS.  Q A FRIEND HAS AN 18 FOOT OPEN BOAT THAT HE HOPES TO
PUT ON THE AIR ON 60 METERS.  HE WAS WONDERING WHAT KIND OF
COUNTERPOISE TO USE WITH HIS WHIP ANTENNA.  HE WOULD NOT WANT TO
DRILL THROUGH OR MAKE ANY MAJOR MODIFICATIONS TO THE HULL.
TRAILING WIRES SEEMS =  END OF 40 WPM TEXT  =  QST DE W1AW  <