This is older THT version. New (SMD) version is there since 3/2022.

K9AY++ RX antenna system with BPFs, Preamp, Controller and much more

The K9AY is terminated loop RX 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. This set including the RF feeder box and the controller.

Main functions:

• Low Noise RX antenna
• Broadband
• 4 directions
• Needs small room
• Great for portable operations
• 50/75 ohm feed line tolerant
• PREAMP with variable gain 0 to 18dB
• Three switchable BPFs or BYPASS
• RX protections / limiters in feeder and controller
• Common-mode filter in feeder
• RX source switch for TX and RX antenna

RF feeder box:

• ONE versions for
  1. Variable load resistor - RLOAD
  2. Fixed load resistor - RLOAD
  3. Easy to set by one JUMPER Manual page
• Common-mode coax choke included.
• PREAMP with variable gain 0 to 18dB
• Three switchable BPFs or BYPASS
• Front-end RF limiters
• High voltage electrostatic protection with neon lamps.
• High power IN/OUT protection
• Safe to use it close to TX antenna
• Easy to use LAN RJ-45 UTP CAT-6 cable. PLEASE read this instructions !!!
• F/B depends also on loop instalation PLEASE read this instructions !!!
• Stainless screws and nuts.
• Quality PTFE SO-239 connector.
• IP56 box.
• Aluminium mounting holder with bracket (pipe max 52mm). More info
• Size 20x15 cm (feeder).
• Available as
  • Assembled product with CONTROLLER - tested
  • PCB

Antenna feeder block diagram:

Controller:

• Universal box for K9AY or 4-way Bi-Dir beverage system - there are BPFs and Preamp only in K9AY++ feeder, not for beverages!
• If you want to use K9AY and 4-way beverage system with BPFs and Preamp, then this is better solution + simply K9AY
• Including Bias tee AC/DC for RX antenna
• Front End protections
• RF power limiters in RX line
• LED direction indicator 0 or 45 deg. Picture
• Rload variable in 9 steps by the switch on the front panel.
• Three BPFs and Bypass - 4 positions switch on the front panel.
• Preamplifier switch and LED indicator.
• RX SOURCE switch. Selecting TX or RX antenna for receiving. More: Picture and Manual

Controller block diagram:

Parameters:

• Supply voltage DC (AC for 4-way) 12 - 14 V up to 2 A
• Preamplifier with NPN transistor 2N5109
• Preamp BIAS current 10 to 70 mA
• Gain: up to 18 dB - preset to 10 dB
• NF < 3 dB
• REAL OIP3 34 dBm
• BPF loss lower than 1dB
• TX power from TRX to TX antenna port up to 400 W
• PTT IN/OUT - only loop, no delay, TX to GND
• PTT logic is 5 V compatible (OM-power)

K9AY++ system includes:

• RF box into the feed point of the ANT loops Picture
• Aluminium holder Picture
• Controller Picture
• Total parcel weight abt 2 kg

Optional Common-mode current choke for coax and control cable

• Optional box Link
• Coax cable current isolator
• Common mode current isolator also for control cable
• You can use part of FTP CAT-5 cable from antenna to this optional box as GND system
• Recommended to place it into the hamshack too. Picture

CMCC-CTRL for K9AY++

Band Pass Filters characteristic:

160m BPF

80m BPF

40m BPF

Band Pass Filters characteristic with preamplifier:

160m BPF with preamp

80m BPF with preamp

40m BPF with preamp

BYPASS with preamp

Videos

User review

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.

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!

Thanks for photos from Laci HA7JTR:

by Laci HA7JTR-HA7I	by Laci HA7JTR-HA7I	by Laci HA7JTR-HA7I

Download

K9AY
RF BOX Manual in WiKi		WiKi for RF BOX
CONTROLLER Manual in WiKi		WiKi for CONTROLLER
rev 1.8		sch	pcb	eagle435
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