The top loaded 160 meter Top Band vertical TX antenna has been deployed for the winter DX and contest season. This year the antenna is based on an 18 meter aluminum vertical with three top loading wires.
The ground system consists of two elevated radials bent to follow the shore line. Both radials are raised from the feed-point in a steep angle to 2.5 meter heigh over the water level, then stretched straight out about ten meter in symmetry from the vertical before they both are bent about 90 degrees South. It is far from an optimal solution, but the antenna is literally standing on water which compensates for the lack of height and the compromise radial system.
The antenna is resonant on 1830 kHz and measures 17.5 Ohm impedance at the feed-point which is expected for a short vertical like this. An unun is used to transform the low impedance to 50 Ohm, then a coax choke is canceling RF in the coax shield. The choke is made using seven turns of RG-213 through five paralleled Amidon FT240-31 cores.
With the vertical up again I will be back on Top Band for the winter season and SE0X is ready for the upcoming contests. We are especially looking forward to the 160 meter contests.
CU on Top Band, 73!