Adding a Security Loop to a Trimble 4700

I recently bought a trio of Trimble 4700 receivers (thanks, Mark!) to serve as backups to my even older 4000-series units. Although I prefer the more robust user interface of the 4000's, the 4700's have the advantage of being smaller and not quite as ancient.

Since I often leave a receiver unattended, I like to be able to lock everything up to reduce the likelihood of theft. My preferred approach with receivers is to install a loop of small-diameter (typically 3/32") stainless steel wire rope to the housing, through which I can pass cable or padlock shackle. With the 4000SSi and SSe receivers, the build-in handle attachment slots make this easy, but the 4700 doesn't come equipped with anything sturdy enough to use for the purpose. I had to use a more invasive approach, but it was pretty easy.

The back end of the 4700 is shown below:

Removing the rubber bumper -- it only requires a bit of lifting and tugging -- exposes the 4 screws that secure the back panel:

Once these are removed, the back panel separates easily:

The electrical cables connecting the panel to the boards inside are short, but I decided it was worth leaving them connected.

I had earlier made a bracket out of 1/6" stainless steel and attached a cable loop to it using a Nicopress sleeve and swaging tool. I forgot to get photos of these separately, but they show up in later shots.

I laid out the required holes using the bracket as a guide; the locations are visible in the shot above.

I didn't want any swarf getting onto the boards, so I inserted a piece of paper with some packing tape attached into the housing to catch it all.

In this image you can see the tape ready to catch the swarf. It worked well in that regard, but removing the paper later was difficult, as the tape wanted to stick to the inside of the housing. For subsequent installs I abandoned the tape and just used paper, being careful not to tip any swarf into the housing.

The final holes, sized to accommodate a 3/16" aluminum pop rivet:

Looking inside, you can see that the drill didn't exit cleanly, as is often the case with aluminum. I carefully slid a sharp wood chisel in there to knock down these burrs.

Here's a shot of the bracket/loop being test fit for rivet hole alignment:

The rivets clear the radio board even before being set:

And there's plenty of clearance once they've been set:

Here's a completed install, with the case buttoned back up (and yes, I did somehow misalign one of the bracket holes, but just decided to live with it):

And all three with their new security loops: