Mode-S Beast:External miniADSB Connection

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There is an option of connecting one external 1090MHz receiver to the board. Any receiver that has an amplitude dependent output would fit here, but mostly recommended is the so called miniADSB receiver from See its own web page on

For the external miniADSB, you need to add a 33R resistor and a 3pin connector to the Mode-S Beast board. These parts, together with a fitting 3pin cable, is delivered one time with the 2CH version of the Mode-S Beast. I strongly recommend using them because they ensure correct polarity of the connection.

Here you can see the connector for the miniADSB on the 2CH Mode-S Beast. Behind the connector there is a 33 Ohm standard resistor, which

  1. causes a little bit of voltage drop in order to avoid oscillation of the miniADSB even more. Anyway, none of my miniADSB ever oscillated, even with 5V directly applied, due to the different arrangement of capacitors.
  2. The resistors acts as a very cheap fuse in case that something goes really wrong

Mode-S Beast PCB

The pinning the cable is

Pin Location Pin Number Usage Color
towards resistor 1 +4,5V supply red
middle 2 GND black
opposite side of resistor 3 Signal input brown

Before using the cable, please swap the brown and the black wire, so that you get black=GND in the center,
red=+5V towards the 33R resistor and brown=signal on the opposite side:

MiniADSB Cable - Picture 1

The original pinning of the cable has misleading colors.

MiniADSB Cable - Picture 2

With a thin pin like a needle or sharp tweezers, carefully press down the lock spring of the cable and easily pull out the cable towards left.
If you press the lock too far, reverse bend it from the inner side of the contact.

MiniADSB Cable - Picture 3

The final color coding of the connector is much more senseful.

The ready made miniADSBs that I deliver do have a right angle mounted BNC connector:

MiniADSB Box - Picture 4

I am using flange mounted connectors with M2,5 threads.
For soldering, I am fixing these from the inner side.
Later, the miniADSB can be mounted to the rear wall with these for M2.5 screws.
The 5 drills are made with CNC machine and fit perfectly.
The screws are part of the ready made miniADSB kit.

MiniADSB Box - Picture 3

From the other side.
The BNC connector is soldered to the box.
Note the two bends on the top and bottom along the BNC,
which is later for the GND connection of the miniADSB board.
The center pin of the connector is extended with a piece of wire.

MiniADSB Box - Picture 2

Fit the PCB into the box
Since the whole of the former BNC connector is below Lambda/10 of 1090MHz,
there is no urgency to close it. If you really like, simply solder two wires in X or + shape across it.
Do not forget to remove the screws before soldering.
I forgot it at each of the first 3 of the series :(

MiniADSB Box - Picture 1

Solder the miniADSB board to the box also at the gap bends you've done before.

The device is now ready to be connected and tested.