Inspired by the American dx'er Gary DeBock, I wanted to try building an FSL antenna.
I used 20 ferrites, 14cm long with a diameter of 8mm, permeability 400, gluing them with double-sided tape around a foam tube of the kind used for learning to swim, cut to 10cm in length, thus providing a solid and light base.
To ensure adequate insulation, I wrapped the ferrites with a thin sheet of bubble wrap turned uspide-down. I then wound them with 1116/46 litz wire in 19 turns, stopped with paper tape, and then soldered the ends to a 500Pf variable capacitor placed on the frame next to the ferrites and stopped with two 300mm x 5mm long clamps.
The original design calls for the ferrites to be placed next to each other, I placed them a little apart as mine was a design using the material I had available at home (considering the diameter of the foam tube, four more would have been needed) but I could observe that the distribution of the magnetic field is not altered anyway.
The winding would also have required 29 turns instead of 19, but this was the amount of wire I had available. I was afraid that this modification would affect performance, but it is a practical example in amateur construction situations, and on reception I could see that even so it works well across the AM range.
Below, the FSL antenna in action with the XHDATA D-808 Supercharged
No comments:
Post a Comment