RX antenna - K9AY loops switch with remotly VARIABLE Rload

This revision is from 2016/10/11 17:53. You can Restore it.

rev.1 6/2016 by Jan OK2ZAW

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

  • PLEASE ADD 10uF/35V CAPACITOR OVER C4 AND C5 IN RIGHT POLARITY !!!

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...

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)

Front side

Front side

Common-mode coax choke

- choke measurements

Wind the coax

- Wind the coax as is on the picture, there should be 7 or 8 turns.

- fix it by one binder and use second one to fix choke to the PCB

Solder the coax

KIT - all parts assembled.

Example of 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 ).
  • MMANA file of my small design for 160 and 80m