[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: Re: Arrow 14 el 70CM RHCP



Also the 3/4 wavelength divides any error's by 3. The 259 and 269 don't
measure impedance at 70cm, that's why I check it at 436.660/3. I don't get
the 50 ohm phasing cable either, but I swapped out a 90 ohm cable and it
started to work much better. Ask Al about that...

73 Jeff kb2m


----- Original Message ----- 
From: "Wayne Estes W9AE" <w9ae@earthlink.net>
To: <satdx@yahoogroups.com>
Cc: <amsat-bb@AMSAT.Org>
Sent: Tuesday, August 26, 2003 4:04 PM
Subject: [amsat-bb] 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
>
> ----
> Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
> Not an AMSAT member? Join now to support the amateur satellite program!
> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
----
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home