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[TowerTalk] Multi-band antenna projects

To: <towertalk@contesting.com>
Subject: [TowerTalk] Multi-band antenna projects
From: gbay@odi.com (gbay)
Date: Sat, 29 Aug 1998 12:22:57 -0400
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Many thanks to all who responded to my questions about top band antennas =
and the Gap vertical.  Consensus on the Gap is that it's pretty good on =
80 but poor on 160.  There's obviously a wealth of info here on the =
reflector and I really appreciate the offers of help.  I'm trying to =
rethink and rebuild my antenna farm this fall and need to get my head =
straight now.

It would seem that the more info I get the more questions I have!  =
Here's my latest list.=20

    1.  I've got enough space to make an inverted L by shorting out the =
Gap and running a wire from its top to the peak of my roof which is =
probably about 40 feet high.  The total length including the vertical =
would be about 130 feet.  (The Gap is about 10 feet down off the side of =
a hill.  I suspect that this might make a fairly decent 160 antenna if I =
put in a good radial system.  However, I lose the multi-band feature.  =
Perhaps an 80 meter trap in the wire?  That might get me two bands =
working better than the Gap alone...what do you think?

2.  Another scenario is to try to load my tower.  It is a TX-472MDP =
motor drive and I keep it retracted most of the time to keep the =
neighbors happy.  The shunt feed would have to go up and down with the =
tower so I imagine that SWR repeatability would be a problem.  Also, =
there would be no way to bond sections together electrically.  Anyone =
ever try this??

3. Where does one get variable and fixed capacitors and inductors =
capable of handling 1.5KW for matching networks?

4.  I'm also rethinking my KT-34.  It's been great with over 300 =
countries confirmed.  However, I now live by the ocean and I have to =
rebuild it frequently because of corrosion.  I'd like to get 5 or 6 =
bands.  I have a Cushcraft AW3-S with the 103 modification to cover 30 =
M.  However, I've never put it up.  One scenario would be to get an =
updated triband antenna and put the AW3-S on top. I'm a little concerned =
about all the metal up there as I only have a Ham IV rotator on a =
TX-472MDP tower.  Also, potential interaction.  Another scenario would =
be to buy a 5 band beam such as the Hy-Gain TH11DX.  Do you have any =
thoughts as to which way to go?  What do
you think of the Th11?  Are there other 5 band beams that you would =
consider?  If you were to get just a three band beam, what would you =
consider?  BTW, I am limited to about a 22 foot turning radius.

Guess I've got a lot of questions...hope it's not too much to ask.

73, Gerry, W1XY


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<HEAD>

<META content=3Dtext/html;charset=3Diso-8859-1 =
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<BODY bgColor=3D#ffffff>
<DIV><FONT color=3D#000000>Many thanks to all who responded to my =
questions about=20
top band antennas and the Gap vertical.&nbsp; Consensus on the Gap is =
that it's=20
pretty good on 80 but poor on 160.&nbsp; There's obviously a wealth of =
info here=20
on the reflector and I really appreciate the offers of help.&nbsp; I'm =
trying to=20
rethink and rebuild my antenna farm this fall and need to get my head =
straight=20
now.</FONT></DIV>
<DIV><FONT color=3D#000000></FONT>&nbsp;</DIV>
<DIV><FONT color=3D#000000>It would seem that the more info I get the =
more=20
questions I have!&nbsp; Here's my latest list. </FONT></DIV>
<DIV><FONT color=3D#000000><BR>&nbsp;&nbsp;&nbsp; 1.&nbsp; I've got =
enough space=20
to make an inverted L by shorting out the Gap and running a wire from =
its top to=20
the peak of my roof which is probably about 40 feet high.&nbsp; The =
total length=20
including the vertical would be about 130 feet.&nbsp; (The Gap is about =
10 feet=20
down off the side of a hill.&nbsp; I suspect that this might make a =
fairly=20
decent 160 antenna if I put in a good radial system.&nbsp; However, I =
lose the=20
multi-band feature.&nbsp; Perhaps an 80 meter trap in the wire?&nbsp; =
That might=20
get me two bands working better than the Gap alone...what do you=20
think?<BR><BR>2.&nbsp; Another scenario is to try to load my =
tower.&nbsp; It is=20
a TX-472MDP motor drive and I keep it retracted most of the time to keep =
the=20
neighbors happy.&nbsp; The shunt feed would have to go up and down with =
the=20
tower so I imagine that SWR repeatability would be a problem.&nbsp; =
Also, there=20
would be no way to bond sections together electrically.&nbsp; Anyone =
ever try=20
this??</FONT></DIV>
<DIV><FONT color=3D#000000></FONT>&nbsp;</DIV>
<DIV><FONT color=3D#000000>3. Where does one get variable and fixed =
capacitors and=20
inductors capable of handling 1.5KW for matching =
networks?<BR><BR>4.&nbsp; I'm=20
also rethinking my KT-34.&nbsp; It's been great with over 300 countries=20
confirmed.&nbsp; However, I now live by the ocean and I have to rebuild =
it=20
frequently because of corrosion.&nbsp; I'd like to get 5 or 6 =
bands.&nbsp; I=20
have a Cushcraft AW3-S with the 103 modification to cover 30 M.&nbsp; =
However,=20
I've never put it up.&nbsp; One scenario would be to get an updated =
triband=20
antenna and put the AW3-S on top. I'm a little concerned about all the =
metal up=20
there as I only have a Ham IV rotator on a TX-472MDP tower.&nbsp; Also,=20
potential interaction.&nbsp; Another scenario would be to buy a 5 band =
beam such=20
as the Hy-Gain TH11DX.&nbsp; Do you have any thoughts as to which way to =

go?&nbsp; What do<BR>you think of the Th11?&nbsp; Are there other 5 band =
beams=20
that you would consider?&nbsp; If you were to get just a three band =
beam, what=20
would you consider?&nbsp; BTW, I am limited to about a 22 foot turning=20
radius.<BR><BR>Guess I've got a lot of questions...hope it's not too =
much to=20
ask.<BR><BR>73, Gerry, W1XY<BR></FONT></DIV></BODY></HTML>

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