SEITENSCHNEIDER SHORTENED DOUBLET 80-10
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- Опубликовано: 29 сен 2024
- Yes, SEITENSCHNEIDER is the name of this antenna. We use this instrument a lot making our antennas, so it's a good name for a well-cut doublet! And I used a plastic packing material of this wire-cutter as a dipole's center support nicely holding the wire and the open-wire line feeder. The feeder line former is another nice discovery by me in one of the BRIKO shops in Brussels: the plastic-made cloth-line. The width of this is about 20 mm and it should make the impedance of the open-wire line in the region of 300 ohms, accordingly to my internet-based calculations. It is not that critical, really the precise impedance of the line. I've red people make doublets out of a zip-cord and they do work. Well, I think the zip-cord based open wire line would be really lossy , I must try it out and see some day though. But for my this experiment my DIY line proved to be an excellent replacement of all sorts of "window lines", "ladder lines" and "twin-lines". It's lightweight and weather-proof and is easy to store away. The doublet itself is 26 m long , comprised of 2 X13 m shoulders. Why 13? Well, could be any length indeed, for a non-resonant antenna but I believed what was tested by Rick DJ0IP and well described on his great site
www.dj0ip.de/o... . So, accordingly to Rick the size of 26 -27 m (88 ft) is still an effective 80m antenna with non-significant loss in signal strength compare to the full size dipole. My impression is this is true after numerous use in the field now during my Flora-Fauna activation sessions.
I am really interested in your experience using such type of shortened doublets, so all comments on this topic are welcome! And let's not forget: the Seitenschneider is the best friend of the Antenna Builder! 73! Linas LY2H
Thank you for the video. I like the idea of one continuous wire on each side of the Doublet antenna. 73 de Bob, M0BOB.
Great video! Subscribed 73
Hilarious while high performance.
Remas ant automobilio kiaurai stoga pragreztas ?
Nop, visas rėmas laikosi and specialiai stogo bagažinei gamykloje įrengtų kronšteinų tvirtinimo vietų. Stogas pragręžtas tik saulės elementų laidams į vidų pravesti ( Ir kemperio ventiliacijos liukams įrengti, aišku ) . 73 Linas LY2H
73 from kb2uew
hi linas，which type of the line for the ladderline ？1.5²mm can work well？thankyou 73
Hi, I think the 1.5 mm wire gauge ( I mean, the diammeter of the wire itself, without the plastic coating) should be OK even for the really high power :) For up to 100W , any wire about dia 0.8-1mm would do nicely. I used just a speaker wire split into two because it was what was in my junkbox anyway :) 73! Linas LY2H
Great job I like how you make your own antennas and prove their worth by making contacts with them.
terrific job Mr balsys good job 73 from kb2uew
Another great video!
Very cool setup. Is there any problem with the ladder line running against the metal van?
Thanks Dean! It's a good question , really. Theoretically, the proximity of the metal van body to the ladder line could evoke kind of disbalance in the RF current float in the two wires. But practically, I have never noticed something unusual like strange SWR readings etc. And not to forget, there is a Guanella (current) type balun at the end which , I believe, effectively corrects the imbalances out , if any. 73! Linas LY2H
I am an experience field operator. I appreciate your videos and your ingenuity… I love ladder line… and a resonant dipole is magical. Thanks Linas, great video!
Thanks Randall! Making antennas is as much fun as using them in the field! Merry X'mas and stay safe! 73! Linas LY2H
I use a doublet at my home station. It works well for 80 thru 6 meters. The only problem I have is when it rains the swr swings up and down and I am constantly having to adjust the tuner.
Thanks for sharing your experience! I'm glad your doublet is doing fine! As to the rain and SWR, well it could be due to the type of feeder line you use. Some so called "window lines" or other lines with plastic dialectric between the line wires are notorious of absorbing moisture ... This brings to the change of feeder line impedance and , thus the SWR. I try to avoid this type of lines and mostly use home made open-air ladder lines where the dialectric is all air. Have fun! 73! Linas LY2H.
Hi. Why you use caoxial cable? Maybe better connect 2 wire line to tuner. Withoute caoxial cable.
Thanks for a good question! It’s because I don’t have the right automatic tuner for the balanced feeder ! :). And the transceiver’s output is 50ohm unbalanced. So I need a Balanced-to-Unbalanced transformer (BalUn) in order for the unbalanced tuner being able to tune the balanced antenna’s impedance. Actually it is possible to connect the BalUn straight to the unbalanced tuner’s antenna port , or get the Balun installed directly in the tuner. (Like it’s done in my manual tuner MFJ-971). In my case, the cable is so short that it’s the same as if the BalUn would be connected directly to the tuner’s antenna port. Besides, my Balun is also a 4:1 current (not voltage) transformer bringing down the high ladder line’s impedance down to more managable for the tuner impedances’ range. 73! Linas LY2H
Tnx
Not a truly balanced antenna if you attach one end to a birch tree and the other to a pine!
Yes, André, you might be right. I am awaiting for my new NanoVNA to come , so I will measure the impedance of the birch trees and pine trees accordingly and will get their Z right into the middle of the Smith chart by trimming the lower branches using the Seitenschneider. Should surely help ! Subscribe for beeing kept uodated on the results!
@@Linas_LY2H Been there! Just be careful of that pine needles, they should have parasitic resonance on higher frequencies.. you should be ok with the birch though!
Have fun!
Really enjoy your channel Linas. When camping I use an End Fed Half Wave on 80m which is also resonant on 40m and 20m. If my campsite is smaller I use a coil shortened 80m EFHW. In Canada we have millions of tall antenna supports disguised as trees! de John VA3KOT