Convert TTIG to TTOG

I bought used outdoor WiFi access point for couple of coffees. At first I wanted to use only the housing for conversion of the TTN Indoor gateway to outdoor gateway. But after some testing and factory reset of the AP I found out it is working and could be configured as stand-alone WiFi MIMO AP. Usually such APs require infrastructure, or at least some management server.

Aruba networks AP175

The conversion requires few steps:

  1. Attachment of the TTIG inside housing
  2. Connecting external antenna
  3. Providing the power supply
  4. Providing access to WiFi
  5. Configuration

Fixing TTIG inside metal housing

Placing of the TTIG inside the housing was easy. There is enough room for complete housing without mains plug. However, I disassembled the housing and took only half of it. Then I attached the lower part of the housing inside the metal box with epoxy glue.

Connecting external antenna

It is good practice to use N type connectors for external antenna connections. There is U.FL connector on the TTIG board. Best solution would be to place “N-to-U.FL” adapter cable, something like this:

N to U.FL adapter cable

Unfortunately I don’t have such adapter cable, which means I need to improvise. I took old cable with U.FL on one side and another with SMA connector and soldered both together. The “N” connectors on the metal housing have SMA connectors inside. The final solution looks like this:

DIY N to U.FL adapter

I know there will be dB or two loss but for initial testing should work fine.

Providing the power supply

The access point uses PoE (active, not the “simple” passive, you can read about difference here). To POwErup the AP I need PoE injector:

Then I follow the power supply path inside the AP and quickly found capacitors with 5V supply.

5V supply (OK, 5,1V)

Now, the tricky part…. I took the jumper with JST connectors and soldered two wires to lengthen the connection. I thought the red is + and black is GND. Wrong! I don’t know if only mine was assebled in that way or there is some hidden feature to confuse “Do-it-Yourselfers” and consequently sell more Gateways due to unexpected smoke escaping from the supply regulator…

DON’T TRUST WIRE COLORS !!!!

Left (at the PCB edge) is positive, right (away from the external edge) is GND

Fortunately I saw small text “+DC” near connector and before connecting the supply I checked the connection. The red wire (on the picture above) is connected to metal cans (GND).

Solder two wires to 5V supply (Red=+5V, grey = GND)

After the gateway was saved from reveresed polarity, I connected the wires to 5V and that’s about it for the supply.

Red = DC+, black = GND

Providing the WiFi acceess

I don’t know if there is enough WiFi signal leaking inside the metal housing, therefore I sacrifice one of the WiFI channels and just left piece of coaxial cable (with 51mm shield removed) inside the housing. It’s simplest dipole antenna.

Simple dipole for WiFi

I will test later if the GW could access access point without that “internal” antenna. One option is to connect the AP through attenuator to the gateway wifi port.

Configuration

The configuration has two steps:

  • access point configuration (out of scope here)
  • Gateway configuration

Testing

Test results will be published after few weeks of outdoor operation.

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