I’ve been thinking about setting up a symmetrical antenna system for a while now.
That is, Ladder line fed dipole.
I did a bit of measuring and was able to stretch 2 x 9m of wire.
I bought a new piece of 10m 450ohm ladder line a while ago. This was too long, but before I put the cutting pliers in it. I rolled up the ladder line on a piece of 120mm PVC Pipe.
I once drilled holes in the window frame to guide the ladder line into the house.
Only in the meantime, all the holes in the window frames were closed and everything was repainted.
So I had to drill a new hole.
This worked out well, since the previous holes were not drilled completely perpendicular through the window frame.
Now I could pay more attention to that and drill 2 nice, beautiful perpendicular holes.
Once inside I had to figure out how to make a quick release connection to the Antenna tuner.
After some thinking I came up with the following.
I found an old thick circuit board. Here the copper is etched off.
I could now make 2 brackets for this, for the inside of the house on the window frame and for the outside.
Since I don’t have a real symmetrical tuner, but an Asymmetrical one, I had to make a TLT (Transmission Line Transformer).
This is a FT-240-43 toroidal core with 2x parallel wires wound with 10 turns.
(5 turns -> crossover -> 5 turns.)
I also made this on a piece of bare printed circuit board, and with a Male chassis PL connector. and 2 M4 bolts.
To ensure that the tuner could tune properly on all amateur bands from 40 -> 10m, I had to play around with the number of windings.