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Distance calculator
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Merry Christmas & Happy New Year 2009
I'd like to take this time to wish all of you a very Merry Christmas.
This is a season of giving, peace, understanding and goodwill among all. I hope that this Christmas will find you among friends and family with good food, good times, and good memories. And I hope too that Santa lines the bottom of your Christmas tree with all the Amateur Radio goodies that it can hold!
Wish you a very happy new year, many nice DX contacts, a lot of pleasure with our hobby and see You in 2009 again!
 The reasons why are DK7ZB yagis popular are following reasons: very good performance and easy building.
We are using DK7ZB yagis too. In recent years we have build:
2 x 3el. 2m 50 ohm crossed for SAT operation
5el. 2m 28ohm for portable use
7el. 2m 28 ohm two stacked antennas
8el. 2m 28 ohm
9el. 2m 28 ohm, two piecs
17el. 2m 28 ohm rope yagi
13el. 70cm 28 ohm, two pieces
 Element holders
DK7ZB yagis for 2m band are realy easy to build. All elements are from Aluminium tubing. We have used two different holders for elements without any difference. The first ones were home made from insulator block 20 x 20 x 40 mm. Drill a hole through the insulator block for element and upright two holes for screws. Saw the block from one side till the hole for element.
Other holder is a professional element holder made by Czech firm. It's holding element without insulating, so we have add underneath it a small plate from insulative material. It's designed for square boom 15 x 15 mm and 6 mm element diameter, so we used it for shorter antennas and 70 cm antennas.
The DK7ZB Match
New coaxial TV cables are very bad for antenna builders. There is very soft PE dielectric that disallow to bend the cable in small diameters and aluminium shield.
We have tried RG6 SAT coaxial with little succes. Very good are "green" coaxial cables with a copper wire and copper shield. Not easy to find it on market!
Radiator is divided in two. The space between tube ends is 12 mm. Inside the tubing is an insulator that stabilize radiator. Connector, tubing and coaxial cable is mounted in standard electrical boxes. Below the connector is an "L" element from an aluminium plate. It's necessary for good contact with a ground after screwing on the boom.
For a water resist we are closing every hole with a silicone rubber.
The DK7ZB match (coax) is oriented to the reflector. We got better results if is this coax oriented there and feeder to the front.
Mechanical resistance
Mechanical resistance of longer antennas is improved by tightening rope. Very good ropes are in climbing shops. We are using them for every reason!
70cm DK7ZB yagis
A piece of DK7ZB coaxial match is for 70cm DK7ZB yagis really short. If you don't got really good coaxial cable, don't try these antennas. We have build few 70cm DK7ZB for this band and it was really hard job.
The performance is good. Mast can't interfere with an element level.
DK7ZB yagi photos
Box with a radiator
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Top view inside a box
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Other view inside a box
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Prepared box
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An L aluminum element
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Tubing
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A top view on DK7ZB match
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DK7ZB match detail
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Other side of DK7ZB match
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Close-up view of coax connection
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Final radiator for DK7ZB yagi
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DK7ZB radiator |
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