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Re: Arrow 14 el 70CM RHCP



This is very cool.  I never thought about making the matching cables 3/4 wavelength long.  That puts the Tee further away from the radiating elements.  It also makes it easy to measure the coax with the MFJ-259 SWR analyzer (not a problem for me because I have the MFJ-269 that does UHF).

It seems to me you would want the 1/4 wave phasing cable to be 90 Ohm coax if it's placed at the "Tee" end of the matching cable, where the impedance is 100 Ohms.  Or you would want 50 Ohm coax if it's placed at the "antenna" end of the matching cable, where the impedance is 50 Ohms.  Did you notice a difference when the phasing cable is moved to the opposite end of the matching cable?

I'm glad it worked, and thanks for documenting how to duplicate it.

Wayne Estes W9AE
Mundelein, IL, USA

-------Original Message-------
From: Jeff Griffin <kb2m@comcast.net>
Sent: 08/26/03 11:11 AM
To: satdx@yahoogroups.com
Subject: [satdx] Fw: [amsat-bb] Arrow 14 el 70CM RHCP

> 
> It work's! On Arrow antenna's Al's N0IMW suggestion I replaced the phasing
stub from 90 ohm coax to 50 ohm . Here's what I'm getting, with 50 watts,
the noise floor here presently is S 2.5, beacon at S 7. SWR is 1.4 to
1....

RHCP   peaking at S 5.5  no fades.
LHCP   peaking at S 4 , with  some fades.
LP (vertical) peaking S 5 with deep fades.

So, I turned the power down to 20 watts, and I'm seeing  S 4.5 peak, the
Arrow  will work FB with my FT-100.

I'm in the middle of writing a major report for work on my recent
re-aligning azimuthally most of the long range air traffic control radar's
on the eastcoat of the USA, so I'm not to keen on writing a paper on this!
But I will gather up all my notes I have on the subject, and add my
finding's in a paragraph or two, and include the all important
measurements.
The big improvement I see is that there are no fades. I had fades so bad
on
LP that I would totally lose the uplink. The .5  S unit improvement is
subjective, but  a bonus. I will post this to the satdx group at......

  http://groups.yahoo.com/group/satdx/

in the files section, this way anyone can see it and we can add to it as
we
need to. Thanks to all who emailed me the very useful information.
Especially Bill W0OQC.

  Jeff kb2m

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