K9AY and Bi-dir beverage controller

last revision 11-2020 by OK2ZAW

K9AY and 4-way Bi-dir beverage Controller

  • This controller allows you to control:
    • Simply K9AY - link (could be only over coax)
    • K9AY++ RF box - link (coax + ctrl cable)
    • Bi-DIR beverage TWO directions - link (only over coax)
    • Bi-DIR beverage FOUR directions with 4-way switch - link (only over coax)
    • You can use some features for more RX antennas


Controller block diagram

RX ANT WAY switch

  • There are two ways how to connect your RX antenna controller to your TRX (RX).
    • 1. Using RX antenna port on your TRX. (Rear panel on your TRX or in Menu) Example
    • 2. Using TX ANT port on your TRX (ANT1) and switch antennas by the controller. Example

Add 1:


  • RX ANT IN and OUT on your TRX:


Add 2:

TX signal way during TXing:

NOTE: RED LED TX must light ON when you TX!!! Do not forget to connect PTT RCA cable from TRX to Controller

  • You can use RX antenna switch on Controller.
    • this is ideal for TRX without RX only antenna port
    • also for the rest TRX for fast RX antenna switching
    • fast switching between TX antenna and RX antenna by knob on Controller
  • If you want to use this feature you MUST use PTT IN to control relay for TX antenna!
  • There is easy PTT loop on rear panel between two RCA connectors.
    • PTT control works only in sniffer mode.
  • PTT can continue to your PA over this box.
    • works also when the controler is OFF
    • there is no delay
    • compatible with 5V PTT logic (as OM-power PAs)

NOTE: PTT must be used!!!

RX SOURCE knob for fast switching of the RX way

NOTE: RED LED TX must light ON when you TX PTT!!!


NOTE: RJ45 is NOT LAN connection!!!

Jumpers settings

Direction LED diode indication

K9AY or 4-way Bi-DIR switching matrix

  • Select between switching matrix.
  • K9AY and 4-way Bi-dir system do have different switching matrix table.
  • bigger picture

K9AY over coax

  • This is for simply K9AY not for K9AY++ (there is switching over the control cable)
  • SHORT jumpers for K9AY direction switching over the coax
  • bigger picture

4-way Bi-DIR beverage settings

ANT Rload fine tune

  • This is function is only for K9AY feeder with Variable Rload part.
  • There are two ways for fine tunning of Rload.
  • Please check some more info about Feeder box of K9AY++ on this link

NOTE: Final Rload resistance may vary with the direction switching. This is caused by thin GND wire between controller and RF feeder box. If the changing is lower than 10 % than all is OK, if more, than more GND wires are recommended. Using CAT-5 FTP (shielded) cable can be big advantage in this problem.

NOTE: For final tunning and measuring, please connect control cable as well also the coax one!

Internal BPF and preamp PCB

This board is only in 4-way system controller. In K9AY++ set all this BPF and Preams are in K9AY++ feeder.

  • It means that if you want to use K9AY++ controller also for 4-way beverage system, than you will have BPFs and Preamp ONLY for K9AY++
  • If you want yo use this internal PCB board, than it is better to buy 4-way system controller + simply K9AY feeder.

Preamplifier GAIN

  • With the variable ATT you can set gain of the Preamp as you need.
  • Range is 0 to 17 dB
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Preamplifier BIAS

  • With this trimmer you can set right bias for the transistor.
  • Bias vs IP3 and gain parameters are there: OK2ZAW's blog spot
  • recomended bias is 45 to 70 mA for 13 V+
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BPF bypass

  • You can use one of three BPF (160, 80 or 40m) or you canByPass it for wideband operation
  • Controller by switch on the front panel - number 4 on controller
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BPF 160M


  • 80M BPF selected by controller.
  • NOTCH filters are included, nulls 160 and 40m.
  • Switch on the front panel - number 2 on controller
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  • 40M BPF selected by controller.
  • NOTCH filter is included, nulls 80m.
  • Switch on the front panel - number 3 on controller
  • bigger picture