Reading in a German magazine called FUNK I wrote an article about a dipole antenna with length of 2x6,5m fed with open line. It's a symmetrical antenna who is not resonant on an amateur band. Because of that the antenna has a high impedance. That easy, connect the feeder to the tuner and we are ready to QSO.
My tuner has a build in 1:4 balun so that the first impedance transformation is done. The PI-filter in the tuner takes care that my TRX sees 50 Ohm. I used a MFJ931 tuner and the Yaesu FT817. The signals are not extremely hard, but in compare to my end fed wire the QRM/N is a lot less. I can use the antenna from 40 - 10m. The restriction on 10m is that I can't get the SWR above the 29MHz below 3. My twinlead is about 7m 300 Ohm (about 12mm wide).
What if I switch the build in tuner in my TS450 off? I Use an Amidon T200-2 iron core to create a 1:4 balun. I connected the feeder via an balun with coax to the transceiver. It works almost the same as the MFJ tuner and the 817, but with the difference that it tunes the whole 10m band.
Lets see if there is a way to use the 80m work with my equipment. Maybe I have to use a feeder with an other impedance. But do I have to change the balun also? I don't know,  I have to try it out. I am going to make the feeder my self. At the do-it-self store I bought some plastic sticks to tight-up plants in the garden. They are real cheap, about 4 Euros for 10 sticks with a length of 50cm. They are strong and very light.
In Rothammels antenna book found some information about the feeder. It's a fact that the impedance deepens on the thickness of the wire and the distance of the wires. I use 1mm2 wire and the have a 60mm distance. This has an impedance of about 600 Ohm.
I used 3 sticks and cut them in pieces from 80mm and 10mm from each end I drilled a 2mm whole. The wire through the wholes and fastened with ty-rapps.
Again testing and see what happens. On 80m no 50 Ohm what the TRX sees. What will happen if I change the 1:4 balun for a 1:9 balun? And now my TS450 sees on the band from 10-80m 50 Ohm including the WARC bands. The signals on 80m are not very loud, but I can use 80m with 100 Watts if I want.
I want to try something different. What will happen to the SWR if I switch my tuner off. And I wondered my self because the SWR on 40,20,17 and a part of 10m stays below 2.
This will be my solution. An antenna 2x 6,5 meter with a home made 600 Ohm feeder and a 1:9 balun.
This antenna hangs now for about a year and I worked a lot of station and DXCC countries with it (mainly in BPSK). During my vacations I want to be QRV from my caravan and this shout be a nice antenna. And I made the same set again and from my /A location it works also very well.
But my XYL is not always happy with my hobby (HI). During the evening when the TV is on see can see when I am in the air. But this problem was easy to solve, twisting the feeders on the balun solved is.
After a couple of weeks I want to try something. Maybe it is possible to feet the antenna with coax. So the feeder disconnected and a 1:4 balun in the feed point of the dipole. The first thing I noticed that the the wind has no influence on the SWR, that because the coax is ty-rapped to the mast. The QRN is a little bit less, but the working of the antenna is almost the same. Without the tuner the SWR on 20 and 10m the less than 2. On all the other band the set sees 50 Ohm when I use the tuner. I changed the 1:4 for a 1:9 balun and there was no difference on QRN. But the SWR without a tuner is now on 40 and 20 less than 2. But also with the tuner it works an all the other bands very well
I let this hang for a couple of days to test it out.