Kevin, Since the phasing lines in this situation are flat 50 ohms, they are not
impedance transformers and so do not need to be multiples of any portion of a
wavelength, they just need to be the SAME electrical length. If you cut them
from the same roll of LMR400 (so you know the velocity of propagation is the
same in each cable) and measure very carefully to be the same PHYSICAL length
you will be fine.. Try to keep them withing an 1/8" or so of the same length..
You can make them as short as possible to reach from the antennas to the power
divider to keep the loss at a minimum..
bill, k1dy
> Date: Mon, 9 Jun 2008 08:39:22 -0700
> From: kevinemtid@sbcglobal.net
> To: vhfcontesting@contesting.com
> Subject: [VHFcontesting] Feedline Lengths for 1296 stacked array
>
> Hi Folks,
>
> I am just about finished my 1296 2x24 ele stacked array. This is the
> antenna from the Aug 2006 QST by W6PQL. But I am in need of the Length of
> feedline from the antennas to the power divider. Am I correct that it has to
> be either a multiple of 1/4 or 1/2 wavelength? Any help would be appreciated.
> This is the last part of the puzzle er array that I need to workout. I will
> be using LMR-400 from the antennas to the PD, then a length of 1/2 Superflex
> to 7/8 hardline.
>
> And one question, I have attached the booms to the vertical supports of the
> H-frame with a ss pipe clamp. Does it really matter where I place the clamp
> screw, on top of the boom or is it ok to be on the side of the boom
> perpendicular to elements? I'm thinking the top of the boom but its a bitch
> to get it set up properly.
>
> Thanks for the help and I will see you during the contest!
>
> 73,
>
> Kevin NZ1I FN41aj
>
> 50, 2, 222, 432, and ?1296( for the 1st time)!
> _______________________________________________
> VHFcontesting mailing list
> VHFcontesting@contesting.com
> http://lists.contesting.com/mailman/listinfo/vhfcontesting
_______________________________________________
VHFcontesting mailing list
VHFcontesting@contesting.com
http://lists.contesting.com/mailman/listinfo/vhfcontesting
|