Dual K9AY Terminated receive loop for 160 meter

With very limited available, this construction uses two seperate receive loops seperated about 12 meters apart. The distance between the two loops are a result of the small space available. The loops are basically placed "where its possible" between trees and other large "objects".

The system consist of three Control Boxes to allow the entire system to be controlled with one control box in the shack.
Control Box #1 and #3 are identical in construction and controls the two directions of each loop.
Control Box #2 acts as a Antenna switch between the the two receive loops.
A control voltage is feed through the coax cable (12VAC/DC). With 0V and +12DC the first loop is selected. With -12VDC and 12VAC the second loop is selected.
The two voltage levels present at one antenna will switch between the two direction of the single loop.

Control Box : Antenna switch (#2)

Antenna switch for selection of antenna. With 0V and +12DC the first loop is selected. With -12VDC and 12VAC the second loop is selected. a 1mH choke seperates RF signal from the relay control voltages.

Control Box : Receive Loop (#1,#3)

Control Box for Receive Loops. a 9:1 trifilar transformer for coupling of loop to 50 ohm.
For the transformer is used a ELFA 3F3 Torrid core with AL Value of 1100 (ELFA Partnumber 58-763-54).
A 100nF in serial with antenna wire avoids DC passing antenna wire itself. Termination is fixed to 390 Ohm (for 160m).
Mechanical layout to the left.

Shack Control Box

Directional control is acomplished using two switches. One for N/S and one for E/W combined the directions: NE, NW, SE and SW. RX Signal to radio (not shown in schematic) is taken from "ANT" with 100nF in serial with the inner conductor of the coax (C1 in this Controlbox wirediagram )