9A3KB - 23m high antenna with capacitive hat and loading coil with variometar used for LF (136kHz) and MF (472kHz) in the future


Special thanks to:

9A2BF Jordan, who made a coil with two variometers for his construction, but he did not use it and finally gave it to me. I had to shorten it for my own need.

9A2PO Zeljko, helped me a lot in measuring and adjusting the antenna.

9A7RV Lucano. He has been precise in helping to produce mechanical details for high voltage insulators.

and other friends who helped: 9A3NRN Neno and 9A2PO Mauro.


Click to the desired picture to enlarge:

As seen at the bottom of the antenna is a large plastic insulator. Inside the closet is a coil with a motorized variometer.
The whole plant is fenced with a fence as animal protection and household warnings.

Into the ground I hit with hammer 12 pieces of zinc-plated tubes. They are all connected with zinc-plated 
metal tape and all together are connected as grounding terminal. 

I was measuring with miniVNA. Here's a chart:

The following image is a variometar control scheme:

The value of the resistor depends on the DC voltage of the motor. Watch out! If the motor turns to the wrong side when mounting, the microswitch opposite will not deactivate the motor so it can do harm if it's strong enough. If that happens just turn the polarity on the motor. SW1 and SW2 are microswitches that activate with the lever on the motor shaft. SW3 and SW4 are DPDT switch with zero position. The LEDs will lit when SW1 or SW2 is activated and remains on for as long as the switch SW3-SW4 is held by hand.