K9AY++ RX antenna system with the Remote Control feature

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The K9AY is terminated loop antenna. It consists of a wire loop of any convenient shape (diamond, delta, etc), hung from a single support and with a ground rod at the bottom. A 9:1 impedance-matching transformer is connected from one end of the loop to the ground and a terminating resistor is connected the other end of the loop to the ground. Antenna has got Band Pass Filters and Preamplifier in the feed point of the loops. It is advantage of filtering and amplification small signals directly from antenna. This antenna is directional. Favoring signals are arriving from the feed point end. You can also change the antenna far field by changing RLOAD (RTERM) of the loop. Feeder box consists of directional switch relay, variable and fixed Rload, matching transformer, front end protections, BPFs for 3 low bands, preamplifier and common-mode filter. Controller allows you to switch all this features over one control cable (8 wires) and there is also Remote Control DB-15M connector for external remote control. This set includes the RF feeder box and the controller.

Main functions:

RF feeder box:

Antenna feeder block diagram:

K9AY matching unit


Remote Control notes:

Technical articles:

Controller block diagram:

K9AY comparation
K9AY comparation K9AY/4-WAY controller is for this beverage system.

K9AY controller with RC block diagram


K9AY++ system includes:

Optional Common-mode current choke for coax and control cable


REMOTE CONTROL directly compatible with OL IP 12:

OLI IP 12 remote

REMOTE CONTROL directly compatible with REMOTIUS 64:

REMOTIUS 64 remote

OLI IP 12 remote

One cable needed:


Band Pass Filters characteristic:

160m BPF

80m BPF

40m BPF

Band Pass Filters characteristic with preamplifier:

BPF 160m & Preamp 10 dB

BPF 80m & Preamp 10 dB

BPF 40m & Preamp 10 dB

Bypass & Preamp 10 dB

RF adapters


User review (classic and remote version):

  • Thanks for email from Robert HA2NP: Congratulations on your great work! First I built the small version of the antenna (3m high). The result is fantastic!The first QSO ZS6 on 80m, on one week around 100 DX on 80m. On 40m new african countries. On 160m I don't have a tx antenna, just a endfed antenna widh tuner, but there are 40 countries in a week ...Sometimes on 20m is also useful for antenna reception (spiderbeam for tx) when bandnoise is high... The controller box design is very nice, I am satisfied! Thanks.

  • by Laci HA7JTR-HA7I

    by Laci HA7JTR-HA7I

    by Laci HA7JTR-HA7I

  • Thanks for email from LISETTE AKESSON: I have tested this antenna in different environments with each of the two loops consisting of 20 metres 0,75 copperwire . The result has been far beyond expectation. Imagine having 4 different beverage antennas to chose between. That's how good the sensitivity is using the preamp in the control unit and when everything is properly grounded. Listening from southern Sweden, many rare transatlantic mediumwave signals have been caught. A specialty which is sometimes very handy is the R-load button that allow you to favorize different angles of the incoming signals. This button has on occasions made unreadable signals totally readable and especially during sunrise propagation. If you have lack of space but can ground well I would strongly recommend this antenna for serious dx-catches.

  • by Lisette

    by Lisette

    by Lisette

    by Lisette

  • Thanks for email from Vesa: Hi! I've been using K9AY++ several weeks now in mediumwave (broadcasting) dxing and my impressions have been only positive. It is always amazing to change the audible stations on the channel by adjusting the direction and resistor knobs. Lots of mediumwave stations from the Far East received so far and this evening at 1700 UTC I received even Australian ABC Adelaide 891 kHz under pressure of Asian stations on the channel. I could never have expected to receive Australian MW-station with K9AY! K9AY++ really rocks!

  • Download

    K9AY++ RC
    RF BOX Manual in WiKi WiKi for RF feeder BOX
    RF feeder rev. 2.3 sch pcb 299
    Controller connector board rev. 3.2 sch pcb 320
    RX/TX switch board rev. 1.1 sch pcb 323
    Front Panel board rev. 1.2 RC sch pcb pcb
    We believe open source is a better way of doing things.
    View and download the Shield Schematic and PCB Kicad/Eagle CAD files,
    LibreCAD .DXF, or Inkscape .SVG files.
    The hardware designs are released under the
    Attribution-NonCommercial 2.0 Generic