Meet FIREFLY: Lightweight, Improvised Portable Relay Nodes (EASY!)


Throwing this out there as a concept and a memory marker, as I’m in the middle of rebuilding the front axle on the Land Cruiser and when I went to look for the crucial component, I couldn’t find it…

Last night it occurred to me how to easily make an outside mount vehicle package to accommodate the goTenna Mesh. The major component would be an old mag mount CB antenna base. Yep, a big ol’ magnet intended to be slapped on your car.

Once I find the one (or more) I know have, I have a short length of 1 1/4" PVC that I will cut so it can be attached to the magnet and allow the GTM to be strapped in. I’m thinking a clear plastic drink bottle could be cut to cover the whole unit for weatherproofing, but maybe the Dole fruit jar would work? With a screw down cap, it would be more secure.

I plan to experiment and post pics soon, but there’s the idea. It can be easily mounted on the hood, roof, or tail hatch of about any car (unless it has aluminum or fiberglass bodywork, of course where magnets don’t really work :smirk: ). It’s easy to detach and secure or charge the battery. You could even rig a power cord for the vehicle to supply 5v to it. Bluetooth should work with the glass windows, especially on the hood or rear deck. IIRC, Bluetooth worked with it on my roof…until it fell off anyway. :cry:


Got the truck put back together. Went to Harbor Freight to get more nitrile gloves - I went through about 150 pairs, as this is a really messy job. Radio is a lot less messy than trucks, let’s do something nice, clean, useful. Something radioy.

This is the latest cool new auto radio accessory, brought to you by goTenna and UMESH’s busy Guerilla :gorilla: Design Team – the Fire Fly Mobile.

While it’s not quite like CB – thank goodness! :violin: – the Fire Fly Mobile takes advantage of the Bluetooth found in every goTenna Mesh to let you mount your GTM unit where it can do some good – outside of the muting radio barrier of the Faraday cage effect produced by being inside a typical metal bodied car.

You may have said…Whhhhaaatt?

It’s this easy. Here’s the pieces.

Pic #1 pieces

Urbana, Illinois, Now a goTenna Mesh Ambassador City!

Having some pics issues tonight so started another Reply in hopes this solves it. Here are your parts.

The plastic jar in this case is from a one pint (16 oz) size container of Nathan’s Famous Sweet Horseradish Pickles (yum! :sunglasses: ) Other jars may serve, but it needs to be a little taller than your GTM.

The key to this project is finding a big magnet. I was still looking for the one I know I have but can’t find when I came across a pair of magnets (Item 65528) in Harbor Freight much like the CB antenna mount I’ve been thinking of, in this case they call them “decor hooks.” These are basically a magnet said to be able to hold up to 65 lbs with a picture hook on one side.

The circular piece of foam came as a separator between the magnets, but works great as the pad in the jar lid. You drill out the rivet holding the picture hanging hook and bolt the magnet onto the lid. I’m going to revise mine to be somewhat sturdier but this is whats holding it together now. Basically it needs a bigger fender washer to avoid the plastic jar lid flexing.

The foam rings (more lile squares) are leftover from the watertight “Apache” containers.

Here’s a way to keep your GTM on the dash.

A better location is out on the hood.

But I didn’t like the clear look and had some paint and a piece of masking tape, so I revised things to look better.

Luckily enough, in that position it clears the garage door, looks great, and works great. I’ve got notions to power it from inside, but for now it’s a temp arrangement. It could also be painted completely and that would look great also. I left the clear area so I could see the status light on the GTM flash.


Blown loudspeakers are a good source for mag mount magnets. A lot of them come apart pretty easily. And many of them have a huge magnet/cone size ratio.


True that.

To keep them from scratching the paint, etc, Zagg, another generic screen protector, or another protective film layer should be applied to the magnet surface that will contact the vehicle.

The HF magnets/“decor hooks” have the protective film already on the item, which is another reason they’re a great bargain. Here’s a pic of the HF magnet packaging.

BTW, did about a 100 mile road test today with the Fire Fly Mobile. Considering I was ony testing the FFM, I decided to leave the GTM out – just in case, considering I’ve already had one GTm do a death dive off my roof. As it turned out, it wasn’t bothered a bit by 70 mph speeds, gusty crosswinds, or the relatively rough ride of the Land Cruiser. The Fire Fly Mobile hung in there gamely.


If you have a screw-on lid, then changing the “skin” on your Fire Fly Mobile is easy. You could even paint it so you could match different color bodywork. Or you could paint up several differently to match the holidays, etc, which would be lots easier than decorating the yard. :smirk:

Also, I wanted to avoid people thinking the FFM is some odd warning light (the Land Cruiser is NOT a school bus) and with it having enough clearance to stay on the roof to get in the garage here at home, I decided on a different look for my FFM.

Painting the whole thing green makes sense if it’s going to be on the roof out of sight, as there’s no way to easily see the LEDs flash as there would be if it was located on the hood as I originally thought would be the case.

This makes it look like a big fat stubby antenna. While it’s size is a bit unusual, stubby antennas are rather unremarkable and common, achieving a bit more stealth.

That, the intense magnet, and being six foot above the ground and in the middle of the roof also keeps some n’er-do-well from getting grabby with it.


This edition of Fire Fly hacks is even simpler than those so far, but very practical for the goTenna Mesh user. The strap on the GTM is a strong silicone-like material that is remarkably pliable. Asking it to be hooked and unhooked every day, as some of us do, could lead to some wear and tear if one isn’t gentle with the button.

If you’re in that situation, I have a quick, simple, low-cost solution. Search for something called a Grimloc D-ring locking clip.

It’s a small plastic carabiner-like item designed to hold up to 80 pounds and to make attaching stuff to MOLLE and olther military load-bearing equipment easy, safe, and silent. It’s durable and has no sharp edges that could cut at the GTM strap. Push the button on top to unlock, otherwise it stays shut. There is a slide clip that fits 1" webbing molded into the inside of the clip that helps keep it positioned.

Grimloc are available in the US from a number of sources, with pricing ranging from $2 to $5/each, depending on quantity purchased, etc. Chinese-made ones, as the one in the pic is, are similarly sturdy and can be had for under $2/each. They also come in various colors.

If you don’t have a handy loop to clip the Grimloc through, you may be able to find a different point where a ty-warp can form a secure loop for the Grimloc to clip into. Here’s one of my handy “man purses” that has a spot for the cell, plus a small loop through which I could run a black ty-wrap, then the Grimloc clips into that to hold the goTenna.

While it is very handy for making personal use of your GTM easier and more secure, the Grimloc is also handy when you need to emplace a stationary node securely. Save the strap, use a Grimloc.


It’s another Guerilla Design Team :gorilla: hack, starting with a previous project by turning it into one that is larger than the rest. And maybe more generally useful since it acts as a mobile relay wherever it goes. It’s now the Meshmobile (see above), sporting its Fire Fly Mobile goTenna Mesh mount improved with full-time power.

I added some gaskets between the magnet and the jar lid, carefully cutting an entranceway that pointed in the right direction so the cable goes in the right direction to eventually enter the cabin below. You need to add enough gasket so that it’s roughly the thickness of the cable.

I plan on adding some more magnetic clips to hold the cable in place. A Land Cruiser can go places where the brush could snag at the cable if it’s not held down well. I’m not sure where this clip came from, but it’s super sticky back holds onto the circular supermagnet that holds it to the truck’s body work

For now, some duct tape helps the positioning of the cable as it slips past the door’s weatherstripping.

I got the 10’ USB micro cable from but it’s a straight-in connection so tight in the pickle jar but does fit. One with a right angle for the end with the micro connector would be better if anyone knows where to get one? In any case, 10’ is enough to do the trick here, bringing the power down from the roof, taking it inside the cabin, and then snaking down to the power connection behind the center console.

The power block is switchable so it can provide continuous power. This leaves the GTM up top on at all times. Thus, the Meshmobile acts as a mobile relay wherever it goes. The roof of the truck makes for a really effective ground plane, helping the signal get out well despite the low mounting height.

The white cable runs up front for handy use to keep the phone device charged.

The Meshmobile will making doing network monitoring much easier. I’m far less likely to lose another goTenna Mesh by leaving it on the roof, driving off and then losing it like I did with the former GTM now known as crashTenna.

Please don’t text and die! of course. Or hurt anyone else. Pull over and do your texting over the mesh safely.


I like it!

I have a Mesh hanging from the coat hook in the back of my car facing outwards, powered by the radio’s USB port through a Voltaic V15. Even though the Mesh won’t charge fast enough or hold enough juice to last a weekend with the car parked, the Voltaic pack can pull enough in to keep going with only an hour a day of the car powered up.

Being up on top of the roof would definitely provide better coverage.


Thanks, MrTSolar!
I would think that the V15 + the goTenna internal battery would be enough to cover the weekend. It has to be close. Do you start with a fully charged GTM?

The circuit the USB charger is on is same as the Primary starting battery, so you dont want to leave it on long term. The truck has an Auxiliary house battery that s independently wired from the rest of the truck, except for the winch. If I did need to leave it on for a long time I can plug into it instead and not need to worry about killing the starting battery. This would be good for multiday music festivals and other longer events.

Yeah, the wide expanse of the metal roof definitely helps reception. Not so much adding extra range, although it seems to aid it a little, but in terms of the reliability of reception.


The Mesh unit on its own won’t last a weekend with no car power, but now it does with the help of the V15. It’s been going strong for a couple months now.


Yeah, that sounds right.


Amen Mike. :+1::sunglasses:


I kludged together a mount for last week’s game to use for monitoring for emergency traffic and to help with info requests. Decided I could upgrade things easy enough into what I’ve christened as the FireFly BigStick.

I painted up a 1.25" PVC tube to match the truck, which is UV-resistant ty-wrapped to the bumper guard (known as an ARB, Australian for “Australian Roo Bar”). I can imagine such a mount also being made to attach to a trailer hitch, go into the side stake pockets on a pickup bed, or other location if you don’t happen to have an ARB available.

Here’s the parts lined up at the bumper. Not shown is a short length (about 1’ ) of 1" PVC pipe that went into the mount first. It centers the broomstick and allows the whole mast assembly to sit a little higher. The aluminum thing on the right is an extensible pole used as a handle for paint rollers. It has a 1" diameter, too, with an old 4" paint roller handle bent to hang the goTenna Mesh, an original FireFly, or other case holding it (like is the case here.)

A 1" PVC tube slips into that semi-permanent mount tube, where the short part of the spacer resides in the bottom of the mount tube, which is about 2’ long. A 1" diameter broom stick goes inside that, with the rest of the 1" PVC pipe going over it. Everything is extended and laid out here next to the Meshmobile. The broom stick shows by how much it’s projecting where that bottom spacer that is already in the mount tube goes.

And here it is, about 15’ in the air, reachable by Bluetooth, but at a much better height for getting your Shouts and other messages out.

At that height, it’s too high for driving around, but that’s fully extended. It can be lowered and adjusted to heights that will clear most everything, i.e. around 11’. Not sure how much driving around like that I’ll do but it provides another option for doing radioscape survey work and the mount should be strong enough , although not sure I’d run with it at highway speeds.

I developed this to give good coverage for monitoring for emergency and info/inquiry messages while working parking at football games. It will also come in handy when camping or attending large outdoor events. The whole contraption breaks down so it stores easily in the back of the truck so it’s always available as needed.

Urbana, Illinois, Now a goTenna Mesh Ambassador City!
Any users in ANCHORAGE Alaska?

lol, I love it! be careful going under power lines


Yeah, don’t want embarrassing moments. I vaguely remember some incident from back in the 70s CB craze when I witnessed a fellow with one of those tall CB whip antennas (102"?) take out a bunch of fluorescent tubes in a low overhang at some gas pumps. Was kinda scary until everyone realized the gas pumps weren’t going to blow.

As for powerlines specifically, the mount is designed to avoid dicey situations getting worse. The PVC pipe and wooden stick are positioned so there’s a weak spot just above the bumper receiver tube. It should break off, but I do want to avoid testing that.:dizzy_face:


I still use on of those 102” whips on my SUV HF ham setup.