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Author Topic: converting old tv antennas  (Read 6725 times)
AE7IS
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Posts: 48




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« on: June 18, 2013, 10:19:39 PM »

looking for input on converting old tv antenna to dual band vhf/uhf use.  Anybody done this?  I've got two old antennas just waiting for a new lease on life, help me get them on the air.
thanks
frank
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KE6KA
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Posts: 12




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« Reply #1 on: June 19, 2013, 02:30:46 AM »

This article explains how to do it.  You must be an ARRL member to view it.

http://p1k.arrl.org/pubs_archive/92933
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VA7VO
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Posts: 13




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« Reply #2 on: June 19, 2013, 02:59:50 PM »

Gave you a reply on your other thread.
Do you have an image of the antenna?
Glenn, VA7VO
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AE7IS
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Posts: 48




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« Reply #3 on: June 19, 2013, 03:57:28 PM »

to ka, yes I saw that, but I'm trying to make this into a dual band antenna, not just 2 meter.  Glenn, I have taken the old antenna apart and cleaned up...boom is around 50 inches, rod stock varies from 25 inches to 4 inches.  I think if I just made a 2 meter antenna and added the 440 element it may work, I'm not sure about interaction between the two and also how to drive both.  I think the distance between elements will change as I add the 440 elements/driver and even the lengths of the elements may change.  That's what I noticed looking at a 2/6 meter converted tv antenna.  I would have thought someone had already done this but I find nothing on the web.
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W4KVW
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Posts: 472




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« Reply #4 on: June 21, 2013, 04:26:04 PM »

Just make sure you put the 2 meter elements on one side of the boom & the 440 mhz elements on the other side so they don't interact with each other.Post some pics of your finished antenna when you are done as well as how well or poorly it's working for you. {:>)

Clayton
W4KVW
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ONAIR
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Posts: 1735




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« Reply #5 on: June 22, 2013, 01:12:13 AM »

Easy to convert an old TV rabbit ears antenna into a 2 Meter or 440 dipole!
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KD0REQ
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Posts: 849




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« Reply #6 on: June 23, 2013, 10:58:33 AM »

most TV antennas from the 70s on were log-periodics, rather like a fan dipole.  try an antenna analyzer on it raw, and see if it's close enough to use as is.
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VU2NAN
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Posts: 237




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« Reply #7 on: July 08, 2013, 05:47:51 AM »

Hi OM Frank,

Here's what I did with my old TV antenna!

http://nandustips.blogspot.in/2011/02/2m-j-poles-and-slim-jim.html

73,

Nandu.
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WA7KGX
Member

Posts: 104




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« Reply #8 on: July 20, 2013, 01:49:53 AM »

Using numbers from Orr's VHF book I cut a ten element channel 2 Yagi
into a wide spaced two meter beam.  I don't have any gain figures but it
was very directive in locating powerline RFI.   I made a 115 mile contact on
two meters AM with it using a converted taxicab base transmitter and AMECO
nuvistor converter.
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WB6BYU
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Posts: 13010




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« Reply #9 on: July 21, 2013, 09:19:38 PM »

The original TV antennas are designed to work on two bands (Channels 2-6 and
7 - 13) where one is (roughly) the third harmonic of the other.  If you take the
current dimensions of the antennas and assume it is designed for 63 and 190 MHz,
then you can divide all the element lengths and spacings by 146 / 63 = ~2.3
and you should have a usable antenna.  That doesn't mean it will be optimized,
but it should work.  (The short elements - less than a foot or so - are for UHF,
and don't need to be included in the later design.)

A better design would be optimized for a smaller frequency range, such as
140 - 150 MHz, rather than 129 - 195 (which is what just scaling the original
antenna would give you.)  Someday I'd like to have the time to develop such
a design:  there may be some around if you look hard enough.
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