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[TowerTalk] F12 Dualies Reply Compendium

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Subject: [TowerTalk] F12 Dualies Reply Compendium
From: (Jonathan Starr)
Date: Sun, 16 Mar 1997 13:34:32 -1000
Thanks to all who commented on the Force 12 Dual
Band Antenna enquiry. I am proceeding to order
the antennas, because the response was so

Here are the replies.


Jonathan Starr KH6X
Helen Nielsen   KH6T


Hi Jonathan:

Well, be sure you order the "D" models of those
I believe that is Force-12's nomenclature for
their ruggedized
versions. they may make one better than that, so
check with them.

At the KE2NL contest station, these antennas have
proven to be
outstanding performers. They go together easily,
ans seem to
survive the nasty winters out here with

This past week, the 3 element 40 meter beam
literally FELL OFF THE
TOWER!!!  It seems the boom to mast plate
developed stress
cracks in it and then shattered during 2 days
worth of
70+ MPH winds.  I believe the plate was defective
to begin
with, but don't know for sure. Explain your needs
to Tom, N6BT,
and have him design a tougher plate for you. 
Your antennas
will have bigger forces on them than ours did,
what with
20 and 40 together on the same boom.  

All told, I do recommend them.

73, J.P. W2XX


Force 12's have survived midwestern winters with
ice and wind while others
Most using report good electrical results, with
some just in awl.  Nice antennas



K5LP is at e-mail address and
has both of those.  He had
them both on a single tower, but is putting up a
new tower to put one on
each tower.  They need really heavy duty rotators
and I would order them
with the highest wind speed rating possible. 
They do this with tubing
inside the normal tubing and it doesn't affect
the wind surface area.  High
wind gusts at k5lp bent a huge self supporting
tower but did not hurt the
antennas.  He did have a problem with the loading
wires shorting out in the
wind at times, though.

Wendell Wyly         W5FL


I am still waiting for a pair of 'H' models
(the elite 3 ele 20m and 4 ele 10m) that I
ordered last Nov 14 th :^(  .

I ordered them through  the Phoenix HRO
and all we get from Force12 is maybe
in a few weeks.  How sad for delivery!

We just had our first 90~ degree day
this week and so it is almost to hot for
climbing :^) may have to rent a crane.



Jonathan:  just be sure to have Tom build them to
the 100 mph spec -- I
think he calls it the "D" rating.

73, Steve K6AW



I have a Force-12 620/340 which has been up just
two years now.  It's at 82ft on a Titan
self-supporting tower.
The antenna survived a nasty thunder storm last
which generated 80mph straight line winds. 
large Maple trees and a few roofs were not as
More importantly, it has survived two Minnesota
One winter storm iced/snow loaded the elements so
they hung just about straight down. They returned
to the 
normal position as soon as the ice/snow melted
off, with
no apparent permanent bend and/or kink. BTW, this
is the 100mph model. 

Re: performance........It is an excellent antenna
on 20 mtrs.
The SWR curve runs per specs. The FWD gain and FB
to be right on the mark also. It has a very
narrow (sharp) beam
width. By that I mean, beam headings are critical
to maximizing
received signal strenghts. If your off 10 to 15
degs from the 
calculated beam heading for a given DX station,
your S-Meter
will let you know.....Hi Hi !  It qualifies as a
"Butt Kicker" !!!!
The 40 mtr antenna performs OK. I suspect that
the height
(82ft) hurts it's performance. I plan on putting
the 40 mtr elements
on their own boom this summer, and stacking it
100 ft. Should
help. It's a good antenna, but no "Butt Kicker".

I've gotten long-winded,sorry about that. If you
need more detail
give me a toot.

Hope things are going well on the islands. I've
been to Hawaii
numerous times, but not in recent years. Hung out
on Maui
most of the time. Love to chase Blue
Marlin...have a 650#                  
hanging above my fireplace.  I wonder what Island
your on?

Aloha.....take care and good luck with your

73, Jim, K0JUH 



I'm putting the 40 meter elements on their own
boom for two reasons:
1. I suspect some interaction (gut feeling), but
    I can't prove it.  Tom Schiller at Force-12
    there is NO interaction and I want to believe

    my friend Tom, however,  my gut feelings tell
    me the antenna doesn't play like it should. 
    Some of this stuff is very subjective.
    if nothing else, I'll sleep better when the
    elements are on their own boom.
 2. I'm changing towers also. The new tower is a
     US Towers 89ft crankup.  By separating the
     elements and stacking 10 ft above the 20,
     40 will gain 20 ft in height and the 20
about 10 ft.
     The current tower is a 80 footer. I'm
willing to bet
      you a Mahi Mahi dinner the extra 20ft in
      will improve the performance of the 40m
      140ft would be ideal, but now I'm

       Wow, Rohn 80 !  Must be a real monster.
       getting too old (62yrs) to climb, so
that's why
       I'm going to the crankup.  

       Yep, I know exactly where you live. I'm
        familiar with Maui.  If I ever get really
sick of
        these damn snowbanks and 30 below, maybe
        I'll move to Hawaii....Hi Hi !

        I'm retired, so spend a lot of time
DXing. Work
        all bands 10 thru 160 CW and SSB. My
        mode is CW. Talk to Jack, KH6CC often on

        If you wanna yak on the air about
antennas, etc
        let me know, and we can pick a time/freq.

 --------73, Jim, K0JUH


Sounds like a great location and tower to put the
Force 12 antennas on.
I've had mine a couple of years and have been
quite satisfied, but there
have been some problems.  The SWR seems higher
than it should be on the
ten meter antenna.  The lowest point is about 1.5
to 1 and goes up to
about 1.8 to 1 at edges.  Still works fine and I
haven't tried to
do anything about it, but does seem it should be
lower at the resonance

The fifteen meter antenna has good SWR
characteristics, as does the
twenty meter antenna.  The twenty is the best
antenna of the lot, in
terms of performance.  

There are a few problems with the 40:  I haven't
been able to get it
adjusted where it has 2:1 or less SWR over the
entire band.  Also, when
you set SWR, after the first wind, the linear
lines get stretched and
the settings are thrown off.  Once the lines are
stretched, they can
come into contact with the sides of the elements
during high winds,
resulting in them shorting out and creating high
SWR.  The placement of
the forty meter driven element is too close to
the mast, making it hard
to install the linear loading lines on the driven
element without them
coming into contact with the mast.  I solved this
by offsetting the
spacer so the linear loading lines are closer to
the element on the side
next to the mast, but that exacerbates the
shorting problem caused by
high winds mentioned above.

I talked to Tom, N6BT, about these problems at
Hamcom last summer.  He
advises the fixes are as follows:  (1) he now
uses hardened line for the
linear loading lines, instead of aircraft guy. 
It also has better
conductivity characteristics.  Use of this line
minimizes detuning due
to stretching of the lines in the wind.  (2) He
recommends moving the
driven element further from the mast, so the
linear lines aren't too
close to the mast. (He may have corrected this
problem on the current
production models by changing the position of the
element.  I recommend
you ask him if he has.)  (3) I have heard he has
a switching arrangement
to switch between SSB and CW, solving the problem
of the antenna not
being broad enough.  Recommend you ask about
this.  It would be worth
getting, if available.)

At present, I set the antenna for best SWR in the
CW band, and use a
tuner when using it on SSB.  I have the 20/40 on
a self-supporting tower
at 62 feet, with the 15/10 about ten feet above
it.  Both are turned
with Hygain HDR 300.  I have Hygain thrust
bearing installed at the top
of the tower.

I am in the process of installing an 80 foot
tower, and will put the
20/40 on top of it.  Later, I plan to install
Magnum 6 el 15 and 8 el 10
on the shorter tower, replacing the 15/10
interlaced arrangment.
When I move the 20/40, I'm going to change to the
new linear lines and
also install a SSB/CW switching arrangement.  If
Tom doesn't have one
available, I'll make my own.  However, I think
the one he uses on the 75
meter beam ought to work, and may try to get

I do strongly recommend all these antennas.  They
are the best I've ever
had, and the problems aren't that bad or hard to
fix.  Current
production changes may have already taken care of
many of them.

Best of luck with your setup.  Let me know if you
have other questions.



Hi Jonathan,

I own some F 12 yagis and I've always been
satisfied, although we don't
have too many extreme weather problems unless you
count the occasional
tornado which I have been luckily able to avoid. 
I do know, however,
that Force 12 makes all of their antennas in a
more stout version, which
I think adds an extra 10% to their purchase
Quoting from the last page of their Spring 96
catalogue, "Antennas are
standardly rated for 80 mph; for 100 mph the "D"
model @ 10% premium; for
120 mph, "H" @ 20%."  I hope this helps you.

73, Mike  N5ZX.


Hi, Jonathan.  I've been real happy, particularly
with the 20 meter antenna.  
It's like a rifle.  You have to aim it quite
carefully - the pattern is a lot 
smaller than, say, a 4-element antenna.  I have
no complaints about its 
mechanical attributes.  My 40 meter bandwidth
isn't as wide as I'd hoped after 
reading the catalog.  I'm a CW operator.  I set
the antenna so that the 
minimum SWR (1:1) was about 7025, hoping that at
7.0 it would be about 1.5 or 
1:8 to 1 and that gave me the entire CW band and
a useful amount of phone 
band.  I've always had to use an ATU on the phone
band, though.  

I'm going to put mine back up soon after moving
it (actually Steve moved it) 
from San Jose to Washington.

CU on the air!  You'll like the antenna.  

Dick, K6KR


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