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[AMPS] High Voltage at Antenna Ends

To: <amps@contesting.com>
Subject: [AMPS] High Voltage at Antenna Ends
From: kc4slk@csrlink.net (Mike Sawyer)
Date: Mon, 11 Sep 2000 20:32:45 -0400
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Remember too, Colin, that it also cuts down on the efficiency.
Mike(y)
W3SLK
  ----- Original Message -----=20
  From: Colin Lamb=20
  To: Amps reflector=20
  Sent: Monday, September 11, 2000 12:18 PM
  Subject: [AMPS] High Voltage at Antenna Ends


  One way to prevent high voltage at the ends of an antenna is to reduce =
the Q.  The easiest way to do this is to use a lossy wire for the =
antenna.  This will also reduce the SWR variations as you change =
frequency. =20

  Galvanized Iron electric fence wire is cheap and reduces Q nicely.  =
Since losses are high, it reduces noise pick up on receive - especially =
from stations a long distance away.=20

  For the ultimate in Q reduction, nichrome works very well.  With at =
least a quarter wave of nichrome, the end insulators can be made of =
silver and they will not introduce appreciable losses.

  Lossy antennas eliminate the need for antenna tuners and eliminate the =
need to calculate 1/4 waves.  They also allow you to tune up on the =
actual antenna without having to bother with the dummy load - a real =
boon to contest operators who like to tune up on frequency. =20

  For quiet reception, the ultimate antenna is created by removing the =
center conductor from 1/4 wave coax and replacing it with 1/4 wave of =
nichrome. =20

  The cubical quad was invented to eliminate corona effect of high power =
antennas.  Beams and dipoles in the Andes had the corona effect and kept =
destroying themselves.  Apparently the designer did not know about =
nichrome.  Instead, he built a quad to eliminate ends of the antenna. =20

  Colin  K7FM

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<META content=3D"text/html; charset=3Diso-8859-1" =
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<BODY bgColor=3D#ffffff>
<DIV><FONT face=3D"BellGothic Blk BT">Remember too, Colin, that it also =
cuts down=20
on the efficiency.</FONT></DIV>
<DIV><FONT face=3D"BellGothic Blk BT">Mike(y)<BR>W3SLK</FONT></DIV>
<BLOCKQUOTE=20
style=3D"BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: =
0px; PADDING-LEFT: 5px; PADDING-RIGHT: 0px">
  <DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
  <DIV=20
  style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>=20
  <A href=3D"mailto:k7fm@teleport.com"; title=3Dk7fm@teleport.com>Colin =
Lamb</A>=20
  </DIV>
  <DIV style=3D"FONT: 10pt arial"><B>To:</B> <A =
href=3D"mailto:amps@contesting.com"=20
  title=3Damps@contesting.com>Amps reflector</A> </DIV>
  <DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Monday, September 11, =
2000 12:18=20
  PM</DIV>
  <DIV style=3D"FONT: 10pt arial"><B>Subject:</B> [AMPS] High Voltage at =
Antenna=20
  Ends</DIV>
  <DIV><BR></DIV>
  <DIV><FONT face=3DArial size=3D2>One way to prevent high voltage at =
the ends of an=20
  antenna is to reduce the Q.&nbsp; The easiest way to do this is to use =
a lossy=20
  wire for the antenna.&nbsp; This will also reduce the SWR variations =
as you=20
  change frequency.&nbsp; </FONT></DIV>
  <DIV>&nbsp;</DIV>
  <DIV><FONT face=3DArial size=3D2>Galvanized Iron electric fence wire =
is cheap and=20
  reduces Q nicely.&nbsp; Since losses are high, it reduces noise pick =
up on=20
  receive - especially from stations a long distance away. </FONT></DIV>
  <DIV>&nbsp;</DIV>
  <DIV><FONT face=3DArial size=3D2>For the ultimate in Q reduction, =
nichrome works=20
  very well.&nbsp; With at least a quarter wave of nichrome, the end =
insulators=20
  can be made of&nbsp;silver and they will not introduce appreciable=20
  losses.</FONT></DIV>
  <DIV>&nbsp;</DIV>
  <DIV><FONT face=3DArial size=3D2>Lossy antennas eliminate the need for =
antenna=20
  tuners and eliminate the need to calculate 1/4 waves.&nbsp;&nbsp;They =
also=20
  allow you to tune up on the actual antenna without having to bother =
with the=20
  dummy load - a real boon to contest operators who like to tune up on=20
  frequency.&nbsp; </FONT></DIV>
  <DIV>&nbsp;</DIV>
  <DIV><FONT face=3DArial size=3D2>For quiet reception, the ultimate =
antenna is=20
  created by removing the center conductor from 1/4 wave coax and =
replacing it=20
  with 1/4 wave of nichrome.&nbsp; </FONT></DIV>
  <DIV>&nbsp;</DIV>
  <DIV><FONT face=3DArial size=3D2>The cubical quad was invented to =
eliminate corona=20
  effect of high power antennas.&nbsp; Beams and dipoles in the Andes =
had the=20
  corona effect and kept destroying themselves.&nbsp; Apparently the =
designer=20
  did not know about nichrome.&nbsp; Instead, he built a quad to =
eliminate ends=20
  of the antenna.&nbsp; </FONT></DIV>
  <DIV>&nbsp;</DIV>
  <DIV><FONT face=3DArial size=3D2>Colin&nbsp;=20
K7FM</FONT></DIV></BLOCKQUOTE></BODY></HTML>

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