[TowerTalk] Re: EF-240 tuning

K7LXC@aol.com K7LXC@aol.com
Thu, 2 Oct 1997 13:32:28 -0400 (EDT)

In a message dated 97-10-02 12:23:24 EDT, you write:

> What is the recommended method for tuning the elements on
>  an EF-240???  
>  I noticed Steve mentioned tuning each one seperately.  How is this
>  done, and what frequencies do you tune for?
>  I've got an EF-420/240 that I'm putting together now, and the only
>  tuning they mention in the manual is after the entire beam is together.
>  It seems to me to optimize performance, you would want to check
>  out each element seperately, and then peak it after the beam is
>  together.
>  I think the EF-240 is really just two EF-140 elements tuned for
>  different frequencies (I think the manual mentions 6.900 for the
>  reflector).  So how is an EF-140 element matched to the coax, or
>  can I just hook directly onto the element to check out the tuning?
>  So whats the scoop?  Whats the best way to tune this thing?
Hi, Lee --  

      You sort of answered your question above (6.900 or so). Check the
manual for the specific frequency. As you recall your yagi theory, the
reflector should be 5% longer (+/-) and the director should be 5% shorter

    Treat the reflector as a dipole (no jumper) and tune it for the frequency
in the manual with your antenna analyzer or swr measuring device. Put the
jumper on when you're done and tune the driven element for where you want it
to resonate. That's it.

73,  Steve  K7LXC

FAQ on WWW:               http://www.contesting.com/towertalkfaq.html
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com
Search:                   http://www.contesting.com/km9p/search