[December 30, 2013]

I purchased a Garmin GDL-39 ADS-B receiver a few weeks ago. I want to hard wire the unit into my airplane, but the cable included was meant to connect to a cigarette lighter powerpoint. I could chop up this cable, but I'd rather not so I can run the GDL-39 from home if needed. I looked into how much a "Bare Wire" kit was for the GDL-39 and I was blown away -- $65 smackers! Time to reverse engineer this cable to see if I can save some money.

The first step was trying to identify the connector type Garmin used. I lucked out and determined it wasn't proprietary - a
Hirose 18 pin Connector. Bonus was it was readily available from Mouser.com. The Mouser part numbers for this cable are

18P CBLE PLUG STD: "ST40X-18S-CV(80)" -- $5.71
CABLE BUSHING: "ST40X-BS(4.0)" -- $0.63

So for $14 shipped, this was looking better than $65.

The next step was determining the pinouts. With a multimeter this was a simple task. Here are my scribbled notes.

A little more detail. This is the connector side. Note the pinouts for ground should be (6,8,9,18)

And the solder points for the "Single Key" side of the connector.

And the "Dual Keyed" side of the connector.

I wired it all up and it works flawlessly. The soldering isn't the easiest in the world since it's easy for the solder to bridge the conductors on the plug. I placed shrink wrap around each pin with a wire soldered to it because the pins tend to bend slightly. With the casing on, this seems like a solid solution. Next step is wiring it up to the RV.



Last Modified: August 13, 2023