RX antenna - K9AY loops switch with remotly VARIABLE Rload

Assembled KIT

Why variable Rload???

- look at far field plots from MMANA

• bigger MMANA far field

The drill drawing

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

Schematic diagram

• bigger schematic diagram

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

• OK2ZAW.com Blog

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.

• bigger schematic

K9AY loops design example.

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

K9AY loops - external links.

• Tom N5EG: Some Observations on the K9AY Receive Directional Antenna