OptiBeam Tech Tip OptiBeam OB10-5M

10 Element 5 Band Yagi This Tech Tip is from Tom, President of OptiBeam Antenna Technologies, call sign DF2BO, known on the air as DF2BlueOcean. A question came up about using 1200 watts of power with the OB10-15M Yagi aantenna.

======================================= Absolutely and by far it is no challenge for the OB10-5M to operate using your 1200 Watt amplifier. DXE offers the better quality baluns from the same maufacturer which we use. Please let me present some very good information on the OB10-5M Yagi antenna. The OB10-5M replaces the wirebeams which we had in our line of products before. The very time consuming work with cutting the wires and doing the pre-assembly does not make any economical sense. This is the reason for discontinuing the wire beams. The OB10-5M is meant to serve hams who look for a small, high performance five-band Yagi which has tubular elements and which is not a wirebeam. The OB10-5M closes the gap between the much bigger tubular fiveband Yagis like our OB9-5 (which is our bestseller for 18 years) and other wirebeams on the market (especially like the Hexbeam). The electrical configuration of the OB10-5M is as follows:

20m: 2el highly efficient Moxon (the very high f/b ratio [32.6 db] on this band is makes this band somewhat more quiet)

17m: 2el driver-reflector combo, approximately 10% of the element length on both elements are bent backwards in terms of a vertical hairpin and make it possible to have these elements fit inside the 20m Moxon

15m: 2el driver-reflector combo

12m: 2.5 el configuration, consisting of a driver + reflector and in addition taking advantage of the 10m director in terms of an element with 50% efficiency

10m: 2.5 el configuration, consisting of a driver + director, and in addition taking advantage of the 12m reflector in terms of an element with 50% efficiency.

The free space patterns and SWR curves of the OB10-5M (plus you’ll find some mechanical data), for such a compact beam has terriffic values, no doubt! Mechanically the antenna is built, to enable it to survive under the most severe weather conditions; here are some highlights:

Sturdy 40x40mm square boom.

6 of the 10 elements are attached to the boom by solid rectangular shaped element platforms which use UV-resistant clamps, and the platforms are installed below the boom with M6 stainless steel square brackets, they principally consist of 12mm round aluminium tubing sections, the sections are connected by 16mm overlays, and these elements, being somewhat closer spaced to each other (for the purpase of saving space), are mechanically connected to the 20m elements by means of high quality fiberglass spacers.

For a sturdy structure throughout the entire antenna, small truss towers with element guy ropes are used to vertically support the elements at three different positions along the boom.

The five driven elements are installed using a directly coupled driver feed system technique, i.e. by two 20x20mm square shaped aluminium tubes that run in parallel to each other, which results in a hyper stable and simultaneously loss-free way of feeding the antenna with a single coaxial feed line, like larger OptiBeam models.

The boom is attached to the mast by a solid aluminium frame, consisting of four right angle aluminum angles, with two M6 stainless steel brackets in the vertical bars to attach the frame to the boom and two M8 stainless steel U-bolts in the horizontal bars to fasten the assembly to the mast.

The pictures show the antenna with a bit more detail and some of the pictures show it installed. Even though the OB10-5M is new in our line of products, we have already delivered close to 30 units and many of them are already installed. I hope that the above information helps show you that you would make an excellent choice with the OB10-5M. Best 73s OptiBeam Antenna Technologies President (Thomas Schmenger), Tom, DF2BlueOcean

DXO-OB10-5 on a Hummelasten Mini-XL

(DF2BO inspecting an OB10-5 installation)

OB10-5M, compact 10 element 5 band beam 20-17-15-12-10m

20m Azimut plot

20m SWR curve

OB10-5M, compact 10 element 5 band beam 20-17-15-12-10m

17m Azimut plot

17m SWR curve

OB10-5M, compact 10 element 5 band beam 20-17-15-12-10m

15m Azimut plot

15m SWR curve

OB10-5M, compact 10 element 5 band beam 20-17-15-12-10m

12m Azimut plot

12m SWR curve

OB10-5M, compact 10 element 5 band beam 20-17-15-12-10m

10m Azimut plot

10m SWR curve

OB10-5M, compact 10 element 5 band beam 20-17-15-12-10m

antenna structure boom length = 3.80 meters (12.5 feet) -> wing span (left to right dimension) = 7,94 meters (26 feet) -> turning radius = 4.38 meters (14.4 feet) -> weight = 23.5 kg (51.7 pounds) -> wind loading projected area = 0.83m2 (8.88 feet2) -> element configuration - 20m = 2el Moxon - 17m = 2el driver-reflector combo with hairpin coil shaped element tips - 15m = 2el driver-reflector combo - 12m = 2.5 el driver-reflector combo + 50% efficiency of 10m director - 10m = 2.5 el driver- director combo + 50% efficiency of 12m reflector -> 2 section square shaped boom, consisting of 40x40mm (1.58” x 1.58”) aluminium tubing -> driven elements connected by the OptiBeam phasing line technique, using 20x20mm

(0.79”x0.79”) square shaped aluminium tubing -> single coaxial feed line

10 September 2019