Greg:
I put up six C3D's and three EF-340D's about 4 years ago and did NOT have to
redrill a single hole! Lucky I guess.
Last month I put out a message about tuning the ten meter driven element on my
C3D's. I found that the distance between the ends of the 10 meter driven
element closest to the 20 meter driven element made a huge difference in the
resonant frequency of the 10 meter driven element. I actually tuned the 10
meter element by using a Delrin dielectric rod as a separator and taping it in
place with 3M electrical tape at the proper place to give me a good SWR curve
using my AEA CIA-HF analyzer right at the feedpoint.
Hope this helps. 73/Mike, N7ML
Kenneth D. Grimm wrote:
> This is very discouraging. When I put up my EF-420/240 I only had to
> re-drill one of the six elements. I thought it was just a fluke.
> 73,
> Ken K4XL
>
> Greg Clark wrote:
> >
> > Well, it's my turn to let you in on some of my Force 12 C3S experiences.
> >
> > I purchased 2 C3S's almost 18 or 19 months ago. They've been in the
> > barn until time and money allowed me to do some work with them. The
> > idea was to have 2 of them in a stack configuration for my second radio.
> >
> > Well, I still don't have alot of time or money, so my goal has been to
> > get one of the antennas on a side-mount dedicated to radio #2. I
> > started working on the antenna on a Sunday and have been doing part-time
> > work on it from that point. It has taken about 3 hours total to
> > assemble.
> >
> > Problems
> >
> > - No major ones, but I was starting to worry. The first element
> > assembled needed to have six rivet holes re-drilled. This number
> > decreased for each element thereafter until I got to an element that
> > needed no drilling..yea.
> >
> > - Tuning...what a pain in the rear..at least for 10m. I've seen similar
> > comments from others and I can tell you "I feel your pain".
> >
> > My tuning setup consists of about 40ft of RG-213...not the 100ft as
> > defined in the manual. I then connect an Autek RF-1 antenna analyzer to
> > one end of the 213 and the other is feeding a new W2AU beam balun. To
> > tune the antenna off of the tower, I hoist the antenna between my 2
> > towers so that it is pointing straight up with the reflector about 6
> > feet off of the ground.
> >
> > Out of the Box - Per the manual SWR points are as follows:
> >
> > 20m (final)
> >
> > 1.5 - 14.0
> > 1.2 - 14.1
> > 1.0 - 14.2
> > 1.3 - 14.3
> >
> > 15m
> >
> > 2.9 - 21.0
> > 2.2 - 21.1
> > 1.6 - 21.2
> > 1.1 - 21.3
> > 1.3 - 21.4
> >
> > 10m
> >
> > 7.5 - 28.0
> > 6.6 - 28.2
> > 5.5 - 28.4
> > 4.4 - 28.6
> > 3.2 - 28.8
> > 1.0 - 29.33 - Kinda high in the band huh?
> >
> > Well, per the manual, I was able to lengthen the 15m element and ended
> > up with a curve that I was happy with. Here is it's final plot.
> >
> > 15m final
> >
> > 1.8 - 21.0
> > 1.4 - 21.1
> > 1.6 - 21.2
> > 2.2 - 21.3
> > 3.0 - 21.4
> >
> > On 10m I was in a pinch. On one of the 10m elements, there were only 3
> > rivet holes to extend the element, on the other 10m element there were
> > 4. Even when I extended the element tips to their maximum, the resonant
> > point on 10 was up at 28.600.
> >
> > So, due to me running out of element tip to lengthen, I then went to the
> > next section of the element toward the boom to look for some extra
> > length. I did this on both 10m elements. This was not a quick and
> > simple process. I finally ended up with the following curve for 10m.
> >
> > 10m final
> >
> > 2.2 - 28.0
> > 1.4 - 28.2
> > 1.7 - 28.4
> > 2.9 - 28.6
> > 4.3 - 28.8
> >
> > It ain't great but it's better that what I started with.
> >
> > >From the time I hoisted the antenna up the first time to the last time
> > that I sat it back on the ground was 2 hours 50 minutes. The majority
> > of that time was jerking around with the 10m settings and then
> > re-engineering it in the field (drill rivets/drill new holes/pop
> > rivets...measure..etc). This was not fun. Thank goodness it's not a
> > big antenna but it was still a pain and to boot it was about 30 deg F
> > all the time.
> >
> > I have another one of these to put up...probably next Summer, but at
> > least I will have my notes to get me through that assembly and tuning
> > procedure.
> >
> > I don't have the antenna on the tower yet. I hope to have it in place
> > for SS this weekend. I'll let you know how it performs, but I did want
> > those that have the C3S and have had problems on 10m to know that there
> > is a way to make it work. I, like other TT posters wonder why the
> > antenna was designed for such a high 10m resonant frequency of 28.800.
> > Why not ship it with about 4 more inches of length in the 10m elements
> > to save the majority of the users the above described procedure?
> >
> > Hope this helps someone out there.
> >
> > 73/Greg
> > K9IG
> >
> > --
> > FAQ on WWW: http://www.contesting.com/towertalkfaq.html
> > Submissions: towertalk@contesting.com
> > Administrative requests: towertalk-REQUEST@contesting.com
> > Problems: owner-towertalk@contesting.com
> > Search: http://www.contesting.com/km9p/search.htm
>
> --
> Ken K4XL
> grimm@lynchburg.net
> BoatAnchor Manual Archive - ftp://bama.sbc.edu
>
> --
> FAQ on WWW: http://www.contesting.com/towertalkfaq.html
> Submissions: towertalk@contesting.com
> Administrative requests: towertalk-REQUEST@contesting.com
> Problems: owner-towertalk@contesting.com
> Search: http://www.contesting.com/km9p/search.htm
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
Search: http://www.contesting.com/km9p/search.htm
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