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Force12 C3-SS

Force12 C3-SS

The C3-ss is basically a 2 element beam on 3 bands. If you are bragging on air it is a 6 element tribander....

 

Why this particular antenna? The biggest reason to me was the size. The actual antenna is full size on all bands except 20m where it is 'linear loaded'. What this actually means is that it has been physically shortened by wrapping the elements into a long loop rather than using inductive or capacitive methods such as traps or loading coils. There are two main advantages to this method. The first is that you don't lose bandwdth from the loading. The second is that there is no lossy components to reduce efficiency or to heat up and break with RF.

 

i bought this antenna second hand and got it for a tenth of the new price. They are not cheap antennas, being completely hand built. They also don't use screws to hold them together but rivets. There is no way this antenna will shake itself loose! I put it back together and put it straight onto the tower. I used both the balun that came with the beam and an ugly balun (choke balun) which now is a standard fitment to all my antennas. Once up in the air a quick check showed it to be perfectl resonant on every band it was designed for and that I had nothing else to do to it except use it.

On Air Performance

In use, it behaves impeccably. It just works. In the first week of using it I added 7 new countries to my logbook on 20m. I can tune up the linear and just operate, knowing that if I fly up and down the band I wont need to retune unless I change band completely. I have used it to good effect when 10m opened up and doing direct comparisons between a 5/8th wave vertical for 10m and the beam shows it to be 2-3 s points better on most signals and can actually hear things that I cant hear on the vertical.

Disaster!!

i was operating one night and I just happened to glance out of the window onto the darkened garden. I saw a glow from the antenna.... Not what you expect so quickly looked at the vswr reading. Completely off the scale. The glow continued when I wasnt transmitting and gradually faded away. B this time I The burnt coax plugdecided it was time for bed anyway so left it all till the morning. I lowered and luffed the tower, and had a look at the coax feed. The insulating tape around the plug was brown and scorched and the paint had come off the balun and had obvious signs of heat damage. I took off the tape and the balun litereally fell apart in my hand. The whole thing had melted internally. I decided to check out the cable and fount the PL-259 had a bit of a problem too. I looked at the manual for the antenna as it was the only antenna that was in the air at the time to see how the manufacturer reccommended it be fed. I was tempted to build a new balun but the instructions said a simple choke balun would suffice because it is inherrently just a dipole and can be fed directly from coax. I did some further reading to check that my ugly balul was sufficient and found that it actually had too much inductance! I didn't need 12 turns of coax for a 20-10m antenna and that 4 turns was sufficient and more efficient. I rebuilt the balun and made the tails to directly feed the beam rather than use a coax plug and socket. As soon As I did that it was perfect again. Back in the air and all was back to normal operation. In fact, receive is slightly better, probably because there is one less connector in line.Revised Ugly Balun

 

 

 

 

 

 

 

 

 

Manufacturers Specifications

 

Just for those who are interested in the tech specs, here is a bit ripped straight from Force12's website.

 

Antenna Boom Lngth Wind Load Frequency in MHz Gain @74’1 Net Gain2 F/B Ratio3 VSWR4 (max) Turning Radius Wt. Mast Torque
C-3 SS 12’ 4.4sqft 14.000-14.350 12.2dBi 4.1dBd 18dB <1.6:1 13.6' 27# <100in/lb
6 elements 18.068-18.168 10.1 1.9 10dB ~2.8:1
(1)
50 ohm feedine
21.000-21.450 12.6 4.7 16dB 425 kHz
<2:1
24.890-24.990 9.5 1.6 3dB ~4:1
28.000-29.700 12.5 4.4 16dB 1.1 MHz
<2:1
 

 

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George Christofi

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