Wow, what a nice day for catching up on some antenna work. I managed to re-orient my 160 meter OCF dipole and I built an extended double Zepp cut for 40 meters and fed with 450 ohm ladder line. Hopefully that antenna will go up tomorrow.
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Antenna day
- Thread starter Lucas McCain
- Start date
OK Mark,
Now that the flood has subsided, I was able to get the Zepp up in the air. The center is in a tree up about 45 feet (oooof), the ends are just tied to trees at shoulder height until I can get them up higher. So the apex angle is only about 90 degrees. I have about 65 feet of ladder line from the antenna to the shack. The Zepp is cut for .68 lambda at 7.1 Mhz. I am using my Dentron supertuner mounted in the window sill for now with it's built in 4:1 voltage balun.
It tuned up beautifully on 20 meters, I think it is working better than my 320' windom. SWR came right down with the tuner. I have no RFI issues and I worked Croatia today with it. So I guess it is going to be a success. I want to get the ends up at 25 feet or so and I can hardly wait until my homebrew balanced tuner is done to see how that works.
Joe
Now that the flood has subsided, I was able to get the Zepp up in the air. The center is in a tree up about 45 feet (oooof), the ends are just tied to trees at shoulder height until I can get them up higher. So the apex angle is only about 90 degrees. I have about 65 feet of ladder line from the antenna to the shack. The Zepp is cut for .68 lambda at 7.1 Mhz. I am using my Dentron supertuner mounted in the window sill for now with it's built in 4:1 voltage balun.
It tuned up beautifully on 20 meters, I think it is working better than my 320' windom. SWR came right down with the tuner. I have no RFI issues and I worked Croatia today with it. So I guess it is going to be a success. I want to get the ends up at 25 feet or so and I can hardly wait until my homebrew balanced tuner is done to see how that works.
Joe
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Thanks for the report, it sounds like a success story! Have you tested to see what bands it'll tune up on or is it no issue with that tuner?My W5GI tunes fine from 160-17 meters, 12 meters, and 6 meters, and is "finicky" on 15 and 10.
I did not try it on 40 but 20 and 15 are excellent, I suspect that it will work fine on just about every band above 7 MHz. The idea is that you cut it long for the lowest frequency that you want. Then you feed it with an odd multiple length open wire feeder. This sets it up so you are feeding a relatively higher impedance than 50 ohms. As long as your tuner has enough reactance, you should be able to get a match.
The tuner I am using now is a Dentron Supertuner which is a "T" network feeding a 4:1 voltage balun. This does nothing for the balance and the fact that it is a voltage balun makes it very lossy with any appreciable SWR. The tuner I am building for this antenna is a balanced "Z" network. The unbalanced input from the exciter feeds a 1:1 current balun on the input of the tuner and the tuner is balanced and floating from that point on. By placing a current balun at the input of the tuner, you are always running it at the lower impedance point of the system and as such, it works well and has virtually no loss because the SWR it sees is never high.
The tuner I am using now is a Dentron Supertuner which is a "T" network feeding a 4:1 voltage balun. This does nothing for the balance and the fact that it is a voltage balun makes it very lossy with any appreciable SWR. The tuner I am building for this antenna is a balanced "Z" network. The unbalanced input from the exciter feeds a 1:1 current balun on the input of the tuner and the tuner is balanced and floating from that point on. By placing a current balun at the input of the tuner, you are always running it at the lower impedance point of the system and as such, it works well and has virtually no loss because the SWR it sees is never high.
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