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Loran to VHF

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fvalarm(at)rapidnet.net
Guest

Posted: Wed Jun 11, 2008 8:17 am Post subject: Loran to VHF

Bob,



Can a Loran antenna (CI 121 SP) be converted/trimmed into a VHF Comm.

antenna?  



Thanks



Bevan

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nuckolls.bob(at)cox.net
Guest

Posted: Thu Jun 12, 2008 2:39 pm Post subject: Loran to VHF

At 09:12 AM 6/11/2008 -0700, you wrote:

 	  Quote: 	
		  

Bob,



Can a Loran antenna (CI 121 SP) be converted/trimmed into a VHF Comm.

antenna?



Thanks


	


  Probably not. LORAN is a low frequency (100 KHz) facility

  that could NEVER benefit from a tuned antenna on a vehicle. Just

  too long. So these antennas tend to be like those used

  on another low frequency (550 to 1700 KHz) system, AM

  entertainment radio. The "coaxial" cable is really a very

  low capacitance, shielded cable designed to minimially

  load a short, e-field antenna that delivers a relatively

  weak signal due to it's Lilliputian dimensions.



  Certainly you can adjust the length of the LORAN antenna

  to make it resonant at VHF comm frequencies but the

  coaxial cable associated with the antenna may very well

  be the low-capacity wire I described. My sense is that you'll

  spend so much time modifying the antenna and then proving

  that you did a good thing that you're $time$ ahead just

  to put a real VHF antenna in from the get-go.



   Bob . . .

        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

        ----------------------------------------

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fvalarm(at)rapidnet.net
Guest

Posted: Thu Jun 12, 2008 6:42 pm Post subject: Loran to VHF

Thanks Bob,



I was considering shortening (tuning) a used Loran antenna for use with a

VHF aircraft radio as a base station for a local airshow coming up.  The

regular 50 ohm coax would be used to feed it.



Bevan 



 



--

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bobf(at)feldtman.com
Guest

Posted: Fri Jun 13, 2008 4:35 am Post subject: Loran to VHF

the LORAN antenna won't work. put "dipole calculator" in google and you will get several automatic calculators for figuring dipole length. put in your frequency and it will give you dipole length - probably about 40 inches or so, take a piece of wire that length, cut in half, solder one end to center conductor and the other end to the shield of rg-58U and you have an antenna. go to RST and they have the formula, they also sell toroids, you could slip on over the coax and that will act like a balun - would take 10 mins to make... mount it "vertical" for vertical polarization - although at an airshow it won't matter.

 

bobf

W5RF

glastar



On Thu, Jun 12, 2008 at 9:38 PM, B Tomm <fvalarm(at)rapidnet.net (fvalarm(at)rapidnet.net)> wrote:

[quote] --> AeroElectric-List message posted by: "B Tomm" <fvalarm(at)rapidnet.net (fvalarm(at)rapidnet.net)>

 

 Thanks Bob,

 

 I was considering shortening (tuning) a used Loran antenna for use with a

 VHF aircraft radio as a base station for a local airshow coming up.  The

 regular 50 ohm coax would be used to feed it.

 

 Bevan

 

 

 

 --

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nuckolls.bob(at)cox.net
Guest

Posted: Fri Jun 13, 2008 10:13 am Post subject: Loran to VHF

At 07:38 PM 6/12/2008 -0700, you wrote:

 	  Quote: 	
		  



Thanks Bob,



I was considering shortening (tuning) a used Loran antenna for use with a

VHF aircraft radio as a base station for a local airshow coming up.  The

regular 50 ohm coax would be used to feed it.



Bevan


	


   That will probably work just fine.



   Bob . . .

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