Arrow CP phasing harness notes

Here are some notes on building the harness.


 Parts needed.

6 male BNC's
1 BNC barrel (double female)
1 BNC divider (2 female, 1 male)
One piece of RG-6 coax 15.25 inches long.
One piece of RG-6 coax 14.25 inches long.
One piece of RG-8x coax 5.80 inches long.


Assembling and testing coax section's


I used an MFJ model 259 antenna analyzer to trim the coax to the required length.
You can use the final length's listed above, I derived at these numbers by using
the MFJ 259 to get the 3/4 wave 72 ohm pieces  as close to 0 ohms impedance with 
the MFJ 259 set to 1/3 of 436.660, or  145.553. This measurement has to take into 
account the barrel connector on one piece, and also a guesstimate of the added
length of the adapter from the MFJ 259 to BNC. The 50-ohm piece is just cut to 1/4
wave at 436.660 as close as  possible, taking into account the velocity factor of
the cable being used. The above lengths are what I finished up with. After several
trial trim's.
 
   Final assembly.

 Attach the shorter piece of 70 ohm coax to the 50 ohm piece with the barrel
 connector. Attach both pieces to the splitter as seen in the picture. The 
 picture shows the harness mounted  in LHCP position.


    Testing 

I installed the Arrow and harness on my satellite crossboom , along side my other
antennas. See the picture of the mounting  position. Both pictures show the 
harness mounted in LHCP position. I found RHCP over LHCP by testing on the air. 
I ended up with the shorter piece of RG-6 (the one connected to the 50 ohm phasing
stub) connected to the horizontal elements in my case, or the element group 6mm 
ahead of the other. There is a noticeable difference when you reverse the 
connection. Once on the air I noticed that proper RHCP gave a stronger signal by 
at least .5 S unit on my 847. Big advantage is no fading of your uplink signal. 
I found it interesting that when I switched between vertical and horizontal 
polarity the horizontal orientation is much stronger. This might change over time,
I only observed this while switched  to horizontal once. 
 There are several pictures of this setup in the files section, also there you 
will find Bill W0OQC, and Arrow antenna's Al N0IMW notes. I hope this is clear 
enough to allow someone to assemble their own phasing harness. Any questions 
feel free to email me direct.

73 Jeff  kb2m@comcast.net