Hello Pete
Force 12 C3 series use the element length to adjust the swr and resonance
point. Some of the older models had 2 sets of rivet holes for frequency
changes
from say the CW to SSB portion of the band. I have a C3-S that's about 8 years
old. As I recall the only element that was made this way was the 10 meter
director. For some reason Force 12 decided that 29.500 was the center of the 10
meter phone band. I don't remember what the other setting was. There should be
a
frequency chart included with the instructions. The easiest way to do this is
to
assemble the antenna, but do not secure the rivets in the last sections of the
elements. Insert the rods and rivets and secure them with black electrical
tape.
Get your hands on an antenna analyzer and with the the antenna about 10' in air
and as clear of any else. Check the SWR and resonance. Start at 20 then 15 and
10 depending where you want to operate. You can check 17 & 12, but you might
spend a lot more time trying to tune these bands and it may have some effects
on
the others. On mine 15 & 20 were fine. It was 10 meters that had to be
adjusted.
That means drilling holes. Your SWR may change some when the the antenna is at
40', but it should not be enough to make much difference. I love my C3-S never
a
problem. The one thing that I did notice is that on mine was that the element
to boom bracket U-bolts were not SS. Good luck. Let us know how it goes.
73 DE K4XZ Joe Patrick
God Made Man
Sam Colt Made Them Equal
________________________________
From: Peter Sils <kd6qv@yahoo.com>
To: "towertalk@contesting.com" <towertalk@contesting.com>
Sent: Sat, November 26, 2011 11:50:36 AM
Subject: [TowerTalk] Force 12 C-3 Question PSE
I know I am dense at times but as I was putting together the elements of my C-3
(bought it used but in new condition) I came up to a point in the instructions
that I do not understand.
Element #3, #5 and #6 have the following instruction:
"NOTE: the initial proper rivet holes for the tip have one hole outside the
.500" section. Double check the drawing to ensure the proper holes are used.
The
outside hole and the inside hole are used for making slight VSWR adjustments if
needed to shift the curve up or down."
My confusion is that the rivet holes (and alignment mark) are lined up for all
three rivet holes to match. If I move the tip rod out one hole the other two
rivet holes do not line up.
Please help me and tell me what I am missing.
I would welcome any insight as to if the C-3 needed any VSWR adjustment (I am
100% SSB). Mine will only be up 40'.
TNX in advance of any help you may offer!
I do have to comment that I am impressed with using rivets to join the
elements!
TNX for reading!
Hope you had a wonderful Thanksgiving!
73 Peter
KD0AA
PS I do have a call into Mark at Force 12 but I suspect he is enjoying the
holiday and I want to get the antenna finished this weekend.
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