I found that my C31XR was also resonant at 21.0 MHz or so. In the end I
adjusted the length of the driven element -- made it shorter by about the
amount the last tip extended from the DE. It was still a bit low and I will
be adjusting it again in July when I work on the Idaho Antennas. I also
found that I needed to make the inductance at the center of the 15m driven
element almost zero to get close to the proper feed point impedance.
I am guessing that there may be some subtle production changes which
occurred when the new Force12 manufacturing was started up. Eventually the
manufacturing problems, if any, will be resolved I am sure.
Tod, K0TO
> -----Original Message-----
> From: towertalk-bounces@contesting.com
> [mailto:towertalk-bounces@contesting.com] On Behalf Of
> Alfredo Vélez WP3C
> Sent: Sunday, May 30, 2010 6:48 PM
> To: towertalk@contesting.com
> Subject: [TowerTalk] Problem With Force12 C31XR
>
> HI
> I installed the Force12 C31XR at 75 feet tall and I have a
> problem in 15M, it resounds in 20.000Mhz and in 21.000Mhz
> have 2:5; when I take out one jumper that connects the
> 10Mdriver with the 20M it downs the SWR in 21.000Mhz to 1:7
> and levels up the SWR in 20M. I don?t know if those jumpers
> made the driver longer and that?s why resounds in the
> 20.000Mhz. I don?t know what to do because it is by the
> manual. Any help will be well received!
>
> Here is a picture: http://users3.jabry.com/wp3c1/Dsc01979.jpg
>
>
> Alfredo Vélez WP3C/NP4DX
> Skype: wp3c.pr
> e-mail: mailto:wp3c@aol.com
> Web: http://www.wp3c.qth.com/
>
>
> _______________________________________________
>
>
>
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