While I do not have the antenna, I do have a pair of C31XRs, which I think the
EF-320 design is implemented into the C31XR's design.
On 20m, the C31XR uses a 5T 2.0" 0.125" hard drawn copper coil across the
feedpoint.
With a W0IYH (?), RG-393 (?) with 100 beads, I have a FLAT VSWR across the
entire band on both antennas. The VSWR is no higher than 1.4:1 anywhere.
Tom, N2SR
From: Wayne Kline <w3ea@hotmail.com>
To: "john@kk9a.com" <john@kk9a.com>; "towertalk@contesting.com"
<towertalk@contesting.com>
Sent: Monday, August 8, 2016 8:33 AM
Subject: Re: [TowerTalk] Force12 EF-320
To add to John's replay. I have no experience with the EF-320 but do on many
of there other antenna models. So are OWA 50 ohm direct feed some are not....
Not sure of your antenna.A quick visual examination can tell if it has a Beta
Match. Tom N6BT used soft aluminum refrigeration tubing as the varying
length loops as his impendence match. So a quick look will tell you if your
antenna has one. As with any trouble shooting I start at one end and work my
way to the other. a dummy load and a few connectors you can check all your
coax and switches out to the tower. Then is a clime in order to check the
feed line connection and the finial end of feed line wring out... In the past
I have experienced Balun F-12, failure.. I assumed it was due to close feed
lighting strikes..... We went to the gray box type with RG142 wound over
stacked cores and overcame the glitch...
YMMV
Wayne W3EA
> Date: Mon, 8 Aug 2016 07:53:13 -0400
> From: john@kk9a.com
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] Force12 EF-320
>
> I have no experience with Force12 beams. However, since your post was
> unanswered and lost in the measuring coax loss within .001dB thread I will
> try to help. I believe that Force12 monobanders are OWA design, meaning
> that the coax is directly connected to the driven element with no matching
> to go wrong. How high is the SWR and how are you measuring this? If you
> have coax in multiples of 1/2 WL lengths you can also check the impedance
> with an antenna analyzer. Did you double check your measurements? Are you
> using the Force12 balun and good coax? Is there anything near the antenna
> that could be detuning it?
>
> John KK9A
>
>
> To: towertalk@contesting.com
> Subject: [TowerTalk] Force12 EF-320
> From: wp3c via TowerTalk <towertalk@contesting.com>
> Reply-to: wp3c <wp3c@aol.com>
> Date: Sun, 07 Aug 2016 10:00:43 -0400
>
> Hi
> I put a Force 12 EF-315 and a EF-320.
> The one for 15M (EF-315) is 1:1 but the one for 20M (EF-320) I'm having SWR
> high.
> Did someone here that have some knowledge about this antenna and could bring
> some help with this?
> Thanks
> Alfredo WP3C
>
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