RX antenna - K9AY loops switch with remotly VARIABLE Rload

This revision is from 2018/02/26 18:30. You can Restore it.

Current version 3.1 - Variable Rload with FIXed JUMPER

Assembled KIT

Why variable Rload???

- look at far field plots from MMANA

The drill drawing

Paste the drawing on the box and fix it with some tape.

Schematic diagram

- Schematic Version 3.1

Voltage controlled resistor

- insert VAC plus to plus - check package

Protection diodes

- solder 5 + 5 diodes

- these diodes protect Rload resistor against high power, electrostatic etc.

Insert rest parts

chooce the control way...

- By the jumper JP2 you can select controlling over coax or DC voltage on connector X3

TRANSFORMERS winding - very important thing!

    • for 50 ohm coax feed line : 2 turns on primar (coax) and 6 turns on secondar side (loop)
    • for 75 ohm coax feed line : 2 turns on primar (coax) and 5 turns on secondar side (loop)

- In version 2.3 and higher, you can select Coax impedance by jumper JP3.

- Transformer should have 5 + 1 turns.

Common-mode coax choke

- choke measurements

Wind the coax

  • Common mode current choke construction
  • Wind 4 turns on one side than cross to another side of cores and wind rest turns.

Solder the coax

KIT - all parts assembled.

Example of controller.

- Injector to coax line:

- direction and VAC Rload controller

K9AY loops design example.

  • It is VERY recomended to place K9AY loop antenna as far as possible from metal towers, antennas and wires. This hepls to obtain better paramaters of antenna ( directivity and noise ).
  • K9AY Loop design page