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Vorläufig / Preliminary, work in progress
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Windom Antenna Fritzel FD4
This web page documents the commercial Windom Antenna Fritzel FD4 measured with the Vector Antenna Analyzer FA-VA5.
On the right side you see a picture of the balun of my Windom-antenna.
One source of buying shows Links #1
If you click on a picture it will be expanded. You can go back to the web page with the back arrow of your web browser.
Technical Data
- Frequency range RX and TX: 80m/40/20m/17m/12m/10m
- Frequency range RX only: ca. 100 kHz to 30 MHz
- max. Transmit Power: 0,2 / 0,3 KW
- Antenna impedance: 50 Ohm (at Balun)
- Antenna connector: PL-plug
- Length: 1x 27,6 m and 1x 13,8 m
- Weight: 1,4 Kg
- Balun Type: 1:6 AMA
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Match Box
Without Matchbox it is not possible to get a good SWR on the 15 m band.
On the 80 m band the bandwith with a good SWR is very narrow. So, a Matchbox is needed.
I am using an old MFJ-941B for tuning and power display.
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Common Mode Choke
As recommended in an ARRL paper about Windom antenna I inserted a 30 cm long common mode choke (15 x 2 cm Ferrite rings Links #4) 6.7 m below the Balun, see the picture on the right. In order to keep the rings on place, they are covered by a black heat shrink tube, see Links #5.
The common mode choke will help to keep the RF (Radio Frequency) out of the shack, see Links #2,3.
The 6.7 m length coax cable HSR195 (Links #6) should help to improve the horizontal radiation in the way to fill the deep nulls.
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FA-VA5 Charts
With my new Vector Antenna Analyzer FA-VA5 I could see very good, how the matching to 50 Ohm is.
On the 80 m band the bandwith of a good SWR (1:1.04) is very narrow, see the chart on the right side.
So, every 50 KHz deviation needs a different tuning.
The actual tuning setup is in the chart comment:
T3.5 means Transmitter capacitor set to 3.5.
I-H means set Inductance switch to postition H.
A0.0 means set Antenna capacitor to 0.0.
The software VNWA is master calibrated, you can see it in the lower left corner of the diagram with letters MC.
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Because the 40 m Band is very small (100 KHz), one tuning setup is sufficient.
The center SWR is 1:1.2.
The smith chart or Smith-Diagramm red curve shows the matching.
The blue curve shows the impedance.
The green curve shows the SWR (Standing Wave Ratio).
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The bandwidth on the 20 m band is wide, one tuning setup is sufficient.
The center SWR is 1:1.4.
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The bandwidth on the 15 m band is wide, one tuning setup is sufficient.
The center SWR is 1:1.10.
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The bandwidth on the 10 m band is wide, one tuning setup is sufficient.
The center SWR is 1:1.21.
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Links
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-- RudolfReuter 2019-01-12 11:37:48
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