Sunday, August 12, 2007


The weekend passed quickly. I did not get a chance to assemble the new Mosley Mini-32-A beam. My goal is to get that assembled and tuned tomorrow night and use it next weekend in the North American QSO Party. I know the pieces fit together, but the instructions indicate that I need to drill holes in the elements once the proper lengths have been determined. That must be done prior to the St. Kitts trip and this week is as good as any other to get this task finished.
There wasn't sufficient time to complete the beam assembly but I did have a few minutes today to spend on another antenna. My Force 12 Sigma-5 antenna had been in storage since my local club's Field Day. I assembled it and put the AntennaSmith on it to be sure it was still in good tune. It was not. So, following the directions in the manual, I spread the coils for the 20m until it gave me a good match. The other bands (10-17m) were fine and needed no adjustment.
The other reason for disassembling the Sigma-5 was to get a glimpse at the controller board. I intend to make a computer model of the antenna and I wanted to see all the details for the matching circuitry.

An antenna similar to the Force 12 was recently released by TW Antennas called the TW2010 Traveler. A somewhat spirited discussion about this new offering erupted on the Yahoo Buddipole Users Group (BUG) forum. I threw in a few comments there, too. Here's what all the fuss is about.
The first thing to notice is that this antenna is very similar in shape to the Force-12 Sigma-5. Both the TW2010 and Sigma-5 are vertical dipoles for 10-12-15-17-20 meters, have control boxes in the center which contains relays for switching bands, break down small for travel, and have a remote control unit that allows you to do the band selection from your operating position 50 or 60 feet from the antenna. Both antennas handle about 1200 watts PEP SSB or about half that for CW. Both antennas claim high efficiencies and relatively low take-off angles.
The question some have raised is: can one of these antennas be efficient and effective? I can only say that the Force-12 Sigma-5 performed well on Georges Island (NA-148) during those operations and compared favorably with other antennas used. The new offering, the TW2010, is smaller, much smaller, than the Force-12 antenna. How will this affect efficiency and performance? That was at least some of the discussion in the BUG forum.
Another big difference between the Sigma-5 and TW2010 is the controller function. The Sigma-5 comes with a simple six position rotary switch for selecting the band. The switch is mounted on an L-shaped piece of plastic with the wires exposed. Pretty cheesy, really.
The TW2010 has a computerized unit that can connect to Icom or Yaesu radios and utilize the CAT interface to automatically band switch. Additionally, the controller cable is detachable with the TW2010 with molded connectors. (The control cable on the Sigma-5 is not easily detachable.) The cable arrangement is certainly nicer than that of the Sigma-5. The computerized controller may be overkill, but it is an interesting design decision.
The TW2010 also breaks down into smaller pieces than the Sigma-5 and requires no tools for assembly or disassembly. A manual is available for download off the TW Antennas web site which has the dimensions, assembly instructions, and other information.
I do have some questions about the antenna and have sent them off to the company. I've received no response yet. When I get those answers, I'll post what I learn here. Of course, should I never get an answer, that'll get posted, too. {grin}

I'm interested in the TW2010, but I haven't decided if the interest is just academic, or practical. I am very impressed with the performance of the Sigma-5 but it is bigger and bulkier than I had hoped it would be. The TW2010 looks like it might pack and travel better, but it is significantly smaller and may not perform as well. Oh, and the other thing: the TW2010 is $699 for the basic unit, nearly double the $379 for the Sigma-5. I'll need to get answers to my questions from TW Antennas, and do a bunch of antenna modeling before I take the plunge on this. Also, it would be interesting to compare computer models for both the Sigma-5 and TW2010, too. Now that I've had a glimpse inside the Sigma-5 and have the schematic for the TW2010, I should be able to create both models.


Blogger WJV said...

Have you come to a decision on the merits of the TW2010 antenna since 8/07.


October 16, 2008 2:10 PM  
Blogger NE1RD's Blog said...

I did. You can read the analysis and comparisons to the other antennas for that size and weight in part one of my white paper collection "Antennas for 100 Pound DXpeditions, Volume 1: Selected high band antennas [20-6m]". The white paper can be found in the download area of my web site

-- Scott

October 16, 2008 2:25 PM  

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