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Reviews For: Force 12 Sigma 80

Category: Antennas: HF: Verticals; Wire; Loop

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Review Summary For : Force 12 Sigma 80
Reviews: 5MSRP: 589.00
Description:
80 meter vertical
Product is in production
More Info: http://www.force12inc.com
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
0054
K0MD Rating: 2008-04-07
Outstanding antenna Time Owned: 6 to 12 months.
I purchased four used Sigma 80's from a fellow ham in town to make a 4 square Array for 80 meters. My wife did not like the elevated radials I had with my homebrew verticals. The antenna is a superb performer. I have it resonant from 3500 to 3850 in the 4 SQR array. It is a pile up buster. I typically do not wait long in pile ups. I have worked ~ 100 Countries with it in the first six months it was up!
The antennas are well built and solid. I strongly recommend this product if you are considering a 4 sqr array or just want a single vertical for Dxing.
W0SA Rating: 2004-11-15
Excellent ! Time Owned: 0 to 3 months.
I have the heavy duty (2 guy) Sigma 80 . It was easy to assemble . The supplied PVC cover for the coils is useless from the factory because it lacks the necessary slots for the feed point and the matching coil ; it comes with a slot for the feed point only . So you have to come up with your own method for keeping snow and ice from the feed point and coil .. I wrapped plastic heavy - duty garbage bags around the area and taped it .
The antenna is about 38 feet tall , and it can safely be put up by one person if you have a 14 ft step ladder .. email me for specifics . ppcross@aol.com .
I like the no - radial aspect ! I've used it with 200 watts on 3.5 CW and worked a 3B9 and HI in pileups .. I think this out-performs a dipole at 60 feet for sure .
I plan a 4 square array this Fall and will post a review on that .
KC5TJG Rating: 2003-05-22
RUN AWAY FROM THIS Time Owned: 6 to 12 months.
Long story short. Fall, 2002: Purchased Sigma 80 and was able to get it assembled with a little redrilling of holes that were off and after requesting they send the hairpin coil that was missing from my package Put power on it and SWR started to drift up after only a few seconds at 1 kw. Called factory. They suggested I wind a coax choke. I did. It worked, but one shouldn't have to home-brew an antenna that costs over $500 for a single band. Antenna worked great until April 5, 2003: Top third of antenna twisted off in a thunderstorm. No other damage on property, neither antennas, trees, or shingles. Not much of a storm. Damgage caused, I think, by the use of swaging of tubing to mate sections, instead of sturdier use of sleeves. The break occured right at one of the swaged joints which had been weakened by the swaging process. Clearly a bad engineering decision to swag the joints. April 6: Wrote a letter to Force 12, including photos, describing damage and asked them to consider replacing damaged parts. I indicated in the letter that if they didn't feel they could do so, fine, I'd purchase the parts myself. Waited. Waited. Waited. April 22: I e-mailed Force 12 asking if they'd received my letter and photos. April 24: Received e-mail response from Force 12 rep in New York, Natan, saying he'd not seen the letter or photos and asked me to send them, which I did via e-mail attachments. Natan responded that he'd received my information and forwarded it to the California office. I waited, waited, waited. May 5: I called the Force 12 office in California and was told that "Mary Ann" handles problems like this. She wasn't in, but would call me the next day. May 6, 2003: Mary Ann didn't call. I e-mailed force12info@fix.net (was told this was Mary Ann's e-mail) requesting information on the status of my request for replacement parts. Waited, waited. No response. May 8, called Force 12 office and spoke with Mary Ann. She said my e-mail had been sent on to "Diane" since she (Mary Ann) didn't actually have an e-mail address. Said she'd check with Diane, get my e-mail, and call me back. No call. May 9: I called Mary Ann again, who said she'd referred my problem to "Tom" and connected me with him. Tom said he'd fix me up with a collar to patch together the broken ends of the vertical section and new tubing to replace the mangled top T-bar. I said great and waited, waited, waited. May 20: I e-mailed Mary Ann, or Diane, or Tom or whoever belongs to force12info@fix.net and asked about the status of the replacement parts. No answer. May 22: Sent a follow up e-mail asking about the status of the replacement parts. No answer.

And that brings us to today. Tomorrow I'll order the parts I need, pay the price, and never do business with these people again. I urge others to also consider carefully if they really want to get involved with an outfit that has so little regard for its customers.

N5OP Rating: 2003-05-14
Excellent, well-made, manual so-so Time Owned: 3 to 6 months.
I ordered, built and erected the Sigma-80 late last winter. This is the latest off-center feed version. I like the idea of a vertical dipole, as without radials it easily will out-perform any 1/4 wave vertical by a wide margin. It would be a close race between this anetnan as a 1/4 wave vertical with elevated radials.

The antenna is hand-built at the factory, and very well-made. Assembly was straightforward, but the assembly manual neglected to mention that there are markings on the parts that make things go more easily. Each part was marked with a vibrating scribing tool with a letter, so the "A" end of tube 2 goes with the "A" end of tube 1, etc. Once this is seen, assembly is a snap.

Erecting the thing is also stone-simple: drive a stake into the ground (rebar works fine) leaving about 4" sticking out, set the base end over that, have a couple of friends to help hold the guys, and tilt it up. Giys are not optional: they are required. The antenna now sports two sets of guys (the maual shows only one). Only one set is needed for typical conditions, but I used both.

My version sported a shroud to go over the loading coils, but it lacked a necessary slot (it needs two and there was only one) and installing the shroud would make tuning difficult. It is needed only for environments that collect ice regularly. Here in Oklahoma, we occasionally get ice but it never lasts long. Accumulated snow and ice would be a problem in more northern climes.

The loading coils are 3/8" soft aluminum, and the instructions in the manual would have them set for the high end of 75 m. Mine are set for the low end of 80 (resonance at ~3520 kHz) and the 3:1 bandwidth is about 70 kHz.

You'll need some kind of 1:1 current balun; I used the Force 12 balun based on ferrite beads. It works fine. It does get warm when running a kW, but this is expected for such a design. The balun does not saturate and there is no danger of damaging the balun at Amateur power levels.

Tune-up is easy. Expect to make about 3 trips to the antenna to set resonance, and the another two to set the hairpin match for a perfect 1:1 at your chosen frequency.

I had perviously used a half-sloper for 80 m, whose performance was only mediocre. The Sigma-80 beats it handily. A four-square of these things would be gangbusters, and even at $600 each, would be cheaper than a 3 el yagi at any reasonable height for 80 m.

I tried tuning it up for 160, but my combination of feedline length and chosen resonance frequency presented a load that my Ameritron ATR-15 could not match belwo about 1.9 MHz. Force 12 will soon have a Sigma-160 out, and I plan to get one as soon as I find a place to put it. I'd buy another Sigma-80 in a New York minute

Kim Elmore, N5OP
W7FU Rating: 2002-10-16
Substantial single band dipole Time Owned: more than 12 months.
I rate the Sigma 80 so highly, because the antenna is what it is: a high performance low band dipole characterized by rugged, quality construction and a conservative, efficient electrical design that I can understand. These dipoles lend themselves to vertical dipole as well as horizontal dipole installations. The Sigma 80 is large, heavy, expensive, and challenging to tune. Not a stealth alternative with the top loading tubing and the guy lines. Mechanical assembly is simple and satisfying.

Have 2 Sigma 80's up for 1 year in a phased vertical array and am very happy with them. A strong reason to incorporate these antennas into my array were their limited size (39' tall) and no need for radials. The resultant installation is compact, relatively neat appearing and fits on my restricted size lot. As individual vertical dipoles, they compare favorably for DX to my dipole@45 meters and a wire full sized GP suspended in the trees. I have dispensed with the heavy white plastic cover for the center loading coils. Instead, the aluminum loading coils were cleaned with TSP and Scotch Brite and painted with enamel. To reduce the possiblity of ohmic losses at the loading coil connections, the loading coils were welded to the antenna tubing at one end and soldered to the balun at the other end. The top and bottom loading tubing pieces were rivited to the mounting plates. To aid in the safe raising and lowering of the antennas for installation and tuning, I constructed a heavy duty integrated hinged base and winch system that permits one man operation.

This type of antenna is not for everyone. The antennas require custom tuning to the operators frequency of interest and because of their high Q design they are very narrow banded. They do fit the bill for those interested in a high performance 80 meter dipole that lends itself to antenna experimentation.