[VHFcontesting] 144 phasing lines

[John (JK) Kalenowsky, K9JK]

Dave,

I HOPE I'm not sticking my foot in my mouth here as I have never actually 
done this myself BUT, here goes (and, knowing this group...I'm sure I will 
be corrected, or at least laughed at, if my foot IS in my mouth)...

WITH Power Dividers, the critical part is to make all phasing lines the same 
length, the impedance transformation is taken care of in the power divider 
so you have "50 ohm" from the transmitter to the power divider common and 
"50 ohm" from the power divider ports to each antenna. SO, to reuse the TWO 
cables you make to use the pair of 2M5WLs this weekend, make the physical 
length of the cables long enough for use when you change to the 4 KLMs (and 
make two more cables of that same length).

You mention "15 foot spacing" for the KLMs so, if that is a quad 
configuration and the power divider for them is going to be at the center of 
the H frame, the length needed would be: 7-1/2 feet from the center of the 
frame to the vertical parts PLUS 7-1/2 feet from the center of the vertical 
part to where the antenna boom mounts on the vertical parts PLUS whatever 
length is needed to get from that boom mount to the antenna feed point.

Length IS very critical when Tees are used to connect antennas together and 
the impedance transformation is done with the coaxial cable...ODD quarter 
wavelength multiples of "75 ohm" cable will 'roughly' transform a "50 ohm" 
impedance to a "100 ohm" impedance which, if paralleled with a second "100 
ohm" impedance, will yield "50 ohm". For this, the velocity factor of the 
cable must also be taken into consideration because the physical length of 
the cable is NOT the same as the electrical length.

JK


From: David Vondrasek <n5ito at davidv.net>
To: vhfcontesting at contesting.com
Subject: [VHFcontesting] 144 phasing lines
Date: Wed, 21 Jan 2004 22:16:06 -0600

Trying to get ready for the contest this weekend and put back up the Duel
2M5WL's for the weekend run. I have a 1/2 power divider and plan to space
14.5 feet apart. I never did understand the formula for cutting the feed
lines from the ant's to the divider. Plan to use  Andrews FSJ4-50B 1/2"
line.   I now have 2 2M5WL ( for the weekend ) but have 4 each KLM 36 foot
boom 18 ele yagi's to put up afterwards. I'd hope to use the phasing lines
from the duel setup on the 4X setup.

So the question is I guess, how long of a line do I need for the 36 foot
booms ( 15 foot spacing ) between the ant's and the power divider ( I have
a 4 way also) assuming I can use two of the lines this weekend for just 2
of the 2M5WL's..

Dave
- Have cable and ends, just how long to cut ?
planned to be on
50 - 5 ele at 45 feet w/ 10 watts
144 -  2X19 @70 feet w/ 225 watts
220 - 20 ele at 40 feet w / 20 watts
432 - 80 ele at 40 feet w/ 10 watts
_______________________________________________

_________________________________________________________________
Get a FREE online virus check for your PC here, from McAfee. 
http://clinic.mcafee.com/clinic/ibuy/campaign.asp?cid=3963