Radio Limeshain

DARC OV Hanau F 09

With very light weight pneumatic switches inserted in the wires, this antenna can be switched into different configurations. The pneumatic switches are activated by using air pressure from a scuba diving tank located in the shack. Pressure is controlled in the shack by 3 way solenoids (the pistons in the tiny cylinders are spring loaded). Polyurethane tubing carries the air pressure to the pneumatic switches located along the wires and does not interfere with antenna radiation.

My good friend and watch maker Norbert Wylenzek took my ideas for the pneumatic switches and made them a reality. Norbert spent a week in his workshop making 10 switches. The quality of Norbert's work is really excellent, and because this was so labor intensive, he really does not want to make any more.

These switches have been in service now for more than five years (summer and winter) with no failures except for two of them which, because I "hot" switched them, failed.

Antenna design was done using EZNEC. The switches are represented in the EZNEC "load window" with 1pf open and "s" when closed. Because of the coaxial design and wide contact spacing, they indeed have only 1pf when opened.

73, Ecki

In August 2012 added experimental full size quarter wave vertical with elevated radials for 80m qrp use

Further below you see various radiation patterns i obtain with my 3 horizontal wires and inserted pneumatic switches

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2008DK8NC