Force 12 Delta 240-140-130 8/26/06

Updated -- Plus some FAQ's about the Delta (after the Delta 240^© & 140^© info)

The Delta 240^© with Tom, N6BT showing the small size

Plug-and-Play assembly, 18' Boom, 39' elements, 5KW, 2:1 bandwidth approx 200 kHz

The Delta 240 2 element 40 meter Yagi is the new generation of shortened 40 meter Yagis. Introduced in 2006, the Delta 240 replaces the long-running Elite Force EF-240S that has brought enjoyment to everyone using it. The Elite Force EF-240S was used separately, plus on the C-4SXL, C-4XL and the EF320-240S. The Elite Force EF-240S elements were 37’ long, linear loading using Alum-O-Weld wire and weighed about 7 pounds, with an operating bandwidth of 130 kHz (VSWR 2:1). The individual dipole elements were used on many products, such as the C-4, C-4S and C-4SS. The entire 2 element Elite Force EF-240S antenna weighed about 26 pounds, including the boom. The most difficult aspect of the antenna was tuning the elements to the proper frequencies for maximum performance. This is because the linear loading had variances during assembly. Force 12 likes our antennas to be "plug and play" and there are only a few that require any tuning at all. We also liked our larger 40 meter elements, the Magnum "N" series, that can be placed very close to other antennas, such as the C-31XR without any concern for interaction. Enter the Delta 240.

Improving on an excellent product is not easy. It took us many years to set and achieve the design criteria for an improved model. This required 2 years of testing. That’s right – it takes a long time to develop new designs, unless you copy someone else (in journalism, this behavior is called plagiarism). The significant enhancements in the Delta 240 are as follows:

Each element in the Delta 240 is a Delta-140 40 meter dipole. These elements are about 39’ long, or 59% of full size. The Delta 140 element utilizes an extremely hi Q (>800) loading coil on each half of the element. The coils are fixed and enclosed in styrene tubes that have been used on our products for many years. Antenna tuning is accomplished by setting the tip lengths. The tip lengths are shown on the drawing of the antenna. This is like the Magnum "N" series: trim the tips and put it up. If other frequencies of operation are desired, the tip lengths are predictable and a chart is included.

Remember all the concern for 40 meter dipoles and Yagis causing problems for a tribander on 15 meters? No more. Unlike other 40 meter dipoles and Yagis you are used to, the Delta 240 and Delta 140 do not resonate on the third harmonic (15 meters). The only other 40 meter dipoles and Yagis like this are also from Force 12 - the larger Magnum “N” 140 dipole and 240N and 340N Yagis. Years of development have gone into this design.

The Delta 240 can be placed within about 3-4' (1 meter) of other HF dipoles and Yagis, without destructive interaction. If you have a tribander, such as a C-3, C-19XR, C-31XR, or a 5-band Yagi such as the incredible XR-5, the Delta 240 can be placed within a few feet on the same mast.

The design of the Delta 240 is a driver element and a parasitic reflector. When they are shipped, the elements are physically the same. This is the same procedure as on the impressive Magnum "N" series. The function of each element is determined by the tip lengths. The reflector is tuned below the desired frequency of operation. This means its tip lengths are longer. The driver tips are shorter. Simple and all you do is follow the chart.

FAQ's -- several have written and called for additional information about the Delta

Q: What is the boom length of the Delta 240? The boom length is 18' and there is no truss cable. We looked at longer boom lengths, but the Delta is designed for a smaller footprint and the 18' length is a good choice.

Q: How about full coverage of the 40 meter band? The easy answer is to select our Magnum 240N instead, with its 58' (85% full size) elements and 24' boom. It covers the whole band, but it is obviously a lot larger than the Delta 240. The answer is to use our 40 meter relay box that we have produced for many years and used on the EF-140S/ EF-240S. It handles lots of power and has a perfect field history of no failures. Normally, only the driver element is fitted with the box and the antenna is set up for the lower portion of the band. If the reflector were switched along with the driver for phone, the reflector frequency would be moved upwards to about 100 kHz below the driver frequency (maybe 7.100 - 7.150, depending on your preference). When working split DX on phone, the stations are mostly below 7.100 MHz. If both elements were switched for phone operation, the reflector frequency (i.e. 7.125) is above the desired listening frequency (i.e. below 7.100), changing the reflector character from a reflector to a director. Remember, the F/B is determined not by the matched frequency of the driver and the reflector frequency, but by the actual frequency of operation and the reflector frequency. In this case, with the reflector frequency tuned above the DX phone band, when you listen in the DX phone band, the reflector becomes a director and the pattern of the antenna would be reversed. With the relay box only in the driver, the reflector always remains a reflector, although the F/B is not optimum when operating transceive in the USA phone band (not working DX split).

Q: Is there a new Delta for 30 meters? Yes. There is a dipole, the Delta 130 and a 2 element, the Delta 230. We are shipping the first Delta 130 today (August 24).

Q: Is there a new Delta for both 40 and 30, like the EF-240/230? Yes. It is the Delta 240/230.

Plug-and-Play assembly, 24' long, (5KW), 2:1 bandwidth approx 200 kHz, 11 pounds

Yes, the Delta 230^© coming soon, as well as the Delta 240-230^© that will replace the long-running EF-240/230