[TowerTalk] C3/C3S

MAERTZ, A REID amaertz@oppd.com
Fri, 2 Oct 1998 09:36:58 -0500


Thanks very much for your replies to my post.

This is a summary of the many replies I received comparing the Force 12
C-3 and C-3S to Mosley TA-33.
Force 12 wins hands down.  Positives include:  lightweight, no trap
design, exceptional mechanical construction, hears well, good SWR on
15/20 and will function on 17/12 well with tuner (not great on 12 with
C3S).  Negatives include narrow bandwidth (C3S) on ten meters and a high
SWR (C3S) on 12 meters.  A number of comments reflect dissatisfaction
with customer service at Force 12.

Excerpts of the replies follow.  I've tried to lift the salient points
and minimize redundance.

I have a C3S I put up this summer, replacing a TA33jr.  It seems to be a
good antenna, but there are some wrinkles:

1.  The F12 bandwidth numbers use coax loss to get those wide numbers. 
I wish my rig had an autotuner, but luckily it's good to 3:1 - I need

2.  Monoband beams seem to be a lot fussier than trapped antennas -
feedline problems that you didn't see before, etc.

3.  If you're a cw/dx man, you may find 10m very disappointing - it's
hard to pull it down below 3:1 at the low end of the band.  Design is
centred at 28.8 - best I could pull it down to was 28.400 centre

My installation is not ideal - roof mounted on rowhouse in city centre
on 15.5' wide lot.  I feed antenna with quad shielded ethernet coax -
the TA33jr was fed with heliax - I'm not a loss nut - the full shield
really helps reduce QRN and TVI. 

I bought a C4SXL which has as its core the C3S.  On ten meters I have
only been able to get 600 kHz bandwidth.  They advertise 1.1 MHz.  I
emailed, faxed and called Force12 to try to resolve this problem and
never got a response from them.  

Unfortunately, the SWR curve was such that the usable (2:1)  bandwidth
was from 28.5 to 29.1.  I had to drill new holes to move the curve down
to where I wanted it.  

To their credit,  I broke an element on my 20 meter elements
getting it down from the tower and they replaced it free of charge. 

The construction and performance of the antenna are very good.  I had
an MP-33, TA-33 and PRO67B before this antenna and it seems to
out perform all of them.  It is noisier than any of them but I think
that is
because it hears better.  My SWR curves are excellent on 20 and 15 and
it seems to work as well as the Pro67 (which covered 17 & 12) on 17 &

My suggestion is that if covering a lot 10 meters is important to you,
for the C3.  Otherwise the C3S will work fine.  At any rate the 18' C3
still be lighter than your TA-33.

Don't count on customer support unless you flame them on TowerTalk. 
Looking back through the archives that seems to be the only way people
get it.

The C3S uses reflectors on all 3 bands and appears to offer  the
most gain for it's  size.  This would seem to be one of the best 
antennas for DXpedition / portable use due to it's light weight
and low wind load and torque, allowing for a minimal support 
structure (i.e. push up mast).   A full size 2L Yagi comes within
1 dB of a short boom full size 3L Yagi.  With trap losses and 
other compromises, the full size C3S should have equal or 
more gain  than most small 3L  trapped tribanders

Weighing in at only 25Lbs it (C3S) sure is easy to haul up the
tower and install... For contesting I find the fact that it doesn't have
that great a front to back an advantage as stations calling you off the
back can be worked wiythout rotating the antenna. The design is simple,
relatively rugged and should last forever  and there are no traps to

"Bad" things to keep in mind "Farce" 12 customer service 
At $500 the thing is over priced.

I have used a stack of Force 12 C-4/C-3 for about two years now and all
can say is THERE GREAT. In the last two years I have ended up in the top
box for every contest I have participated in. The antennas are at 73'
40'. Spend the money and get the c-3 over the c-3s.

I replaced a TA-33 with a C-3S and I am very happy with the new
antenna....(just worked E31AA for a new one)
It beats the pants off the TA-33 and is lighter and easier to install...
12M is so-so.....but 17 is great... 20 es 15 are very good...10 hasn't
open that much to try it out...

I've used a C3s (well, actually the C4S) for 3 years now and am very
with it. The 10 meter bandwidth is adequate with a tuner for the higher

I've put a C3 up as a replacement for my TH7DXS . The No TRAPS route and
almost half the weight difference ( 31lbs. ) along with the pop rivet
as opposed to hose clamps has me convinced I made the right choice. The
has much better front to back rejection. However, the C3 performs
and in some cases better then my circa 1989 TH7. 

In addition, I use the C3 on 12 and 17M with good results, this type of
operation was
not possible with the TH7.  I only use a Rohn HDBX 48' tower so the C3
at about a 53-54' height above ground. 
SWR spots. 
For a C3S:

SWR on 12 sucks so far, but I need to change out a piece that f12 cut to
wrong size on 20m ele, so we'll see then.  18meg swr is abt 4:1, again,
we'll see.  It fires "backwards" ON 18!  What I understand is that it
like a driven element and DIRECTOR rather than DE/Reflector 2 ele on
bands.  SWR on 20/15/10 is fine (as it is on 40 -- I operate almost all

I "think" the C-3S might be harder to stack, whereas the C-3 has a nice
gap between elements in about the right place.  Otherwise, I agree, the
C-3S would seem very competitive.  Can't see for sure on the web page,
you might check this if it's a meaningful consideration for you.

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