I'm a HAM. Not that I'm funny, seriously, I'm a HAM. An amateur radio operator. I function as an emergency contact for neighborhood issues when infrastructure is down, as well as a point of contact and support for the city (I work with both data networks as well as voice networks in the radio environment). I also work for a local healthcare company on their radio connection network in my spare time. It's not what I do for a career, this is what I do for kicks and giggles. My current portable radios are poor, my wife doesn't want an awful antenna sticking up from the house, and that leaves either a permanently mounted in the vehicle (it's been broken into once or twice, so things are not left in there) or a portable base station with some power.
Old ammunition storage boxes are often referred to as "ammo cans", so taking it into the world of radio and adding an "h" on the front is not a long stretch. I am NOT the coiner of the phrase "hammo can". I refuse to take credit on coining the terminology because, frankly, I'm not that smart.
Under the circumstances outlined above, a "hammo can" is the perfect option. It will be light weight, portable, and not tied to a vehicle or property. I can easily set one up under a canopy in the yard if it's needed. So, I finally decided (11 years after first obtaining my radio license) to venture into the "hammo can" world. So, that proverbial bullet was bitten, and I started ordering parts :
- The radio is a TYT's "TH9800D". It's tried and true, and a lot of HAM operators swear by it. Theoretically, it will fit a Yaesu FT-8900, but I cannot confirm that without a radio. This one also requires three m4-0.7 flat head machine screws, one being 16mm long and the other two being 12mm long.
- The container is a 50 caliber ammo can off of Amazon. I ordered it in purple (they have other colors, and this one visually separated itself from my grab-and-go case of hard drives).
- The battery is a 12v LiFePo battery to be able to run this station for an extended period of time.
- A power manager (AtemPower AP100BM) is used in this build (and some switches so I can completely disconnect the battery for storage).
- Battery terminals (2 negative [black], one positive [red])
- Random switches and battery connectors for easier charging.
- Heat-set inserts for m3 screws - while it started out with some m2 screws threading directly into the plastic, it was eventually changed to all-m3 (except for the radio itself) for consistency.
- 27 m3x10mm machine screws (add four if you print this with the two-part top plate).
- 2 m3x10mm pan head screws (for the radio face-plate-to-battery box).
- Heat shrink tubing
- 1/4"-hole circular connectors
- 1/4" female spade connectors for the battery
- A PL-259 90-degree elbow
- 4" Cable with PL-259 ends (male and female)
- Mounting connector for a PL-259 for the top plate
- Wiring (I used a radio adapter that had long cables, and I just used the extra cable for all my power needs)
So, I have the hardware to have a "hammo can", but it is kinda ugly piled into a chaotic mess, and I don't want to re-organize everything before I can use it in an emergency. I need this thing to be ready to run with only setting up an antenna. The simpler it is in an emergency, the better.
Design
That lead me on a course to print an insert for the "hammo can". I mapped out a lattice, and started gluing things together in FreeCAD. Please note - by the end of this write-up, the structure will change. There is no lattice for rigidity, and it is all handled completely by brackets. This will give more parts to print, but reduce the over all time it takes to print it. But, let's skip this digression and just move to the original design.
There are compartments to slide the battery into, the radio into (faceplate goes on top), and the power management adapter. So, I also loaded the "thing" to thingiverse if anyone else wants to go down this course of action.
I think this will work sufficiently, but it looks like it's just about 2 weeks to print (17 days). Plus, without a brim, it looks like it just barely fits on a Creality CR-10s build plate (with a brim, it did not fit). I do want to make one change - I'd like to make the radio area a bit more "modular" so you could potentially use other radios, so this could become a more viable option to build one-off hammo cans. We'll see if I do.
I got into gear by printing the power module bezel (I was using it as the test platform for interrupted filament prints because the chassis is going to be 2.5 reels of filament (yes, that much). I don't want to be so attentive for two weeks while this prints, so an empty filament reel should result in a pause. That's two prints that I can use to make sure it is all running properly. The power bezel print did abort, while I figured out the issues with the filament sensor housing, and I printed a new housing and had it working okay, so I could run some more tests.
I managed to get the bezel printed with interrupted prints, so I think I can test this once I get the time to do it (mid-to-late August at this point).
The bezel plate came out great.
The bezel plate will just screw in to the chassis. There is one section I'm going to have to modify for a power shunt, so I might as well get the radio caddy a little more modular, too. I spent a few hours getting things set up for a modular setup.
I then built out the shunt plane, as well as a modular radio, and also printed out the switch plane while I was at it.
The switch panel looks good.
There are two "generics" in the thingiverse file - one radio module and one shunt plane. But I also have the shunt plane for the AtemPower monitor and the TH-9800D radio loaded in there. The "generics" are in case you want to try something a wee bit different (e.g. fit in a different radio, for example).
I then started to print the shunt plane for the AtemPower (not the generic one - I don't need one of those). Of course, the shunt plane print failed four times. I re-leveled the bed, changed the nozzle, and then finally gave up and ordered a new PEI printing bed plate (I ordered a few, just because this could use up more consumables like the print bed). Then I started printing it yet again. I'm getting close to running out of filament on one spool, so this is perfect - it's going to give me a real test of the filament sensor break.
The print was good - it finished right on time. The shunt plane finally finished, and did not warp. Now, if this should look funny, it's because I wanted to finish using up my silver filament. I knew during one of these parts I would have an opportunity to prove out the filament sensor interruption, and it came about 2/3's of the second to last layer. So, the base is "black", but the last layer is "silver". It's going to be buried in the can, so I'm not at all worried about a discrepancy. This print took about 4.5 hours with the filament reload.
Now for the radio module. Since I had the silver installed, I simply just went for that. It will all be hidden on the back end, so I'm not terribly worried about presentation here.
Again, I created a "generic" in the thingiverse file for this, but also a specific TH-9800D variation for my implementation. If someone wants me to do a non-generic module for a different radio (if they fit in the same basic size), they can always donate a radio and I'll try to design it to make it happen. Again, in theory, this may fit a Yaesu FT-8900 or 8800 radio (since that is what the TYT TH-9800 is based on), but no guarantees. Send me one, and I'll make sure it does work. I probably won't send the radio back when I'm done.
I only printed the TH-9800D radio bracket, not the generic, so I cannot vouch for the generic one's functionality, but the specific one came out well. I assume the generic one is fine, since the TYT-specific one was based on it. This print took about 16 hours.
I realized that my measurements were 0.039" off on the screw spacing, so I adjusted the module, but rather than take 16 hours to reprint, I just modified it using a drill. The radio body fits in using one m4-0.7-16mm screw on the top and two m4-0.7-12mm screws on the bottom.
Next came the print that would take a few weeks, the one I've been testing the filament change in anticipation of - the actual chassis. Seeing that my previous prints have come out slightly undersized, I did a quick google search, only to find out that an STL doesn't have real dimensions in it, so your slicer can only guess so much. This means that you have to adjust the size in your slicer before you slice it. That leads me to the following. The chassis itself is 6.102" (154.9908mm) wide, 11.217" (284.9118mm) long, and 6.315" (160.4010mm) tall. Okay, on to the printing. My slicer seemed to have it pegged on dimensions well, so, off to the printer. I know I should adjust for shrinkage, but meh. We'll see.
This should start out in silver filament (because, again, that's what is on there), but should switch to black before the top layers when the silver filament runs out (it takes 2.5 rolls of filament, so it will definitely run out) - and that means it should look just fine on the outside. My CDO (OCD in the right order?) will know the bottom is silver, but it will still function.
Yeah, that's a few layers of silver below the black. Sure, it's going to look whacky, but I don't care. (The fact that I am yet again referencing this "issue" probably means a second print later.)
This is going to take a while. The slicer said 13.4 days, but the print isn't coming across at the same rate. After 33 hours of printing time (started on the 11th at 8:54 AM), I've calculated each percentage point as taking 249 minutes, or 4.15 hours. The stats claim that it will take a grand total of 17.3 days (on the dot, which puts it at finishing on the 28th at 2:54 PM) - which is what 415 hours equates to.
At the 20% mark (8:10 AM this morning on the 14th, 72 hours and 9 minutes in, I revisited the stats. The target date shifted from the 28th at 2:54 PM to the 26th at 8:46 AM. The per-percentage time went from 249 up to 277, which makes me question my math in one of these two check points. We'll see what happens. It does look good, and taking random photographs will help me post-process the supports, clearing this up. As I work through it, the photos will definitely come in handy.
The next check point, 7:37 AM on the 15th, was 27% complete, with about 1.888" of height, 94 hours and 36 minutes into this (5,676 total minutes so far). On this one, I took the time to also measure the chain guard distance to the stabilizer, because I know the stabilizing rods get in the way of the x chain. That came out as 6.146" of height remaining, and the calculations are to 5.664" of height left (which falls a lot longer than the 6.315" of total height).
This 21,022.2222 minutes in total, or 14 days, 14 hours, and 22 minutes. That brings the new estimate of completion to the 25th at 11:16 PM. Of course, there are some filament changes that will have to happen in there somehow.
My next check point came in a few times on the 18th, while I started paying closer attention to the filament running out for a second time. I clocked it at 171 hours and 51 minutes at 12:51 PM, and had the filament changed at 172 hours and 15 minutes at 1:39 PM, approximately 24 minutes in print time, but 48 minutes apart. That means that the print timer itself is total time, and does not include time between filament being out to the change time - or print pauses. That's good to know.
So, the estimate for the next filament change is the 24th at 8:46 AM. At that point, we should be about 97% to 98% done with this, and we'd only have 1 day and 7 hours, and 53 minutes remaining (25th at 4:39 PM is the new completion target, depending on how much time I waste forgetting I need to change the filament).
It is now 62% done, but at 59% done, it was 203 hours and 45 minutes into the print, and 4.374" tall. If this was fully linear, it would mean that the print would be 7.414" tall, but we know that the print should only be 6.315", so we have nearly a full inch shorter. This is a solid indicator that the print percentage is NOT in layer count, it is either in over-all time, or in total distance of filament printed. At this rate, it should be 5 days, 21 hours, and 35 minutes remaining, a target completion of the 25th at around 9:50 PM.
Now, if only I could wait patiently (and hope we don't have a power outage in the next 5 days, 13 hours, 22 minutes, and 46 seconds).
Bugger.
9 days in, at 66.3% complete, I walk into the room (I'm not living in the same room as this thing for a week) and hear odd noises.
The nozzle is being scraped across the top of the print!
Apparently, I printed a 6.35"x6.1"x4.6" pile of a roll of filament. I aborted the print job, and grudgingly went back to the drawing board. [sigh].
No fancy lattice work, no huge set of prints, and all of the modular parts will still fit. This also includes other improvements that were re-developed int6o the new structure (I thought I would see interference on the corners with the curves in the can itself, so I added some fillets to work around that). So, off to print a few parts for the printer itself, then to start with the four new parts :
- The bracket that ties the shunt plane to the radio, the battery, and to the top plate
- The extra corner bracket (where I have some space that could be used in the future if I wanted to add networking components or Raspberry Pi's)
- The new top plate with mounting tabs
- Battery box
All said and done, these four new parts should take approximately 5 days to print - a massive difference in time down from the 15 days it was going to take. Additionally, these new brackets can also be adjusted to make this even more customizable. The top did not fit with a raft - so I created a 2-part top plate. However, I really don't like the visual, but it does still function, so if you are making one of these without a large printer, it will still work.
The top parts did get plastic-welded together after being bolted with screws. Here it is without the plastic-weld, which is still functional.
And the visual... really isn't so bad! The top panel pieces took 40 hours and 40 minutes on the CR-10s with 100% infill and a raft, which is why the surface is a bit sub-par. Here it is with the top panels all combined, and with no wiring.
Next was the battery box. Started at 9:44 Aug 31, followed by the brackets. And, after all that, it finally started to come together!
Assembly
- Install the heat-set inserts in ALL the parts. If you used the two-part top plate, you will use an extra four of the inserts, and an extra four of the m3x10mm machine screws.
- Next, install the radio itself to the radio module.
- If you printed the two-part top plate, combine the two top plates together with four screws. Plastic-weld the two parts together (*this is purely optional*).
- Fit the switch plate to the top plate, and screw together.
- Install wiring on the radio body side of the switch (you won't be able to get to that after you install the radio).
- Temporarily install the radio face plate (the part that comes with your radio) to the adapter block, but do not tighten.
- Install the radio face plate to the top plate.
- Measure where the radio adapter bracket (what came with your radio, not the block itself) sits, and remove the block and radio face plate.
- Re-install the radio adapter bracket without the radio face plate itself to the adapter block.
- Install the radio face plate adapter block and bracket to the top chassis plate again.
- Shift the radio face plate adapter until it matches what was measured above in step 7.
- Tighten the radio face plate adapter bracket (what came with the radio) to the adapter block.
- Remove the adapter block, and add the cables required for the radio face plate, and install the face plate to the adapter block/bracket combination.
- Install the battery box to the top plate through the radio face plate connector.
- Install the radio face plate to the top chassis, running cables into the cavity underneath the box where they can be connected to the radio.
- Fit the power module into the bezel, then attach it to the top plate.
- Install the battery connectors for the top plate.
- Install the radio module itself to the top chassis.
- Install wiring to the battery, and to the power module, the remaining switch terminals, the battery terminals, the battery box (add the connectors for the battery, too) and the radio itself. In my case, the negative battery was wired to the switch, then to one battery terminal. I essentially used the battery posts on the top chassis plate for the interconnection of wires.
- Install the extra bracket.
- Install the shunt plane bracket (not the adapter).
- Insert the battery to the battery box, and strap it in using a velcro strap (not really required, but recommended to prevent the battery from bouncing around) to secure it in position.
- Route wires around the shunt plane bracket.
- Install the radio module shunt plane adapter and shunt plane.
- Program the radio using your computer (again, while optional, I highly recommend it).
- Drop the block into the hammo can.
- Weather strip around the top edge to lock the panel into position and secure the chassis.
I did use a strap to hold the battery when I started putting it together. It rattled around and went flying through the air and landed on toes when pulling the chassis in and out of the can while assemling.
I finally got the last few parts to finish putting this together (the one remaining battery terminal, and the antenna connector).
It does fire up, and things appear to be operational!
Your radio should now be ready for an antenna and an emergency. A good source of information is the "Radio Reference" database (https://www.radioreference.com/db/aid/7771) where you can look up frequencies specific to your location. I would recommend (if your radio supports these frequencies) :
- 27.065 (CB Channel 9) - Emergency
- 52.525 (6-meter) - FM emergency band for ham radio operators
- 138.225 - FEMA disaster relief (primary)
- 146.52 (2-meter) - non-repeater, HAM frequency
- Local Fire, Police, and Search and Rescue (frequencies will vary by location)
- 156.75 - maritime weather alerts
- 156.80 - maritime distress
- 163.4875 - national guard emergency channel
- 163.5125 - armed forces disaster preparedness
- 168.55 - federal civilian agency for emergencies and disasters
- 243.00 - military aviation emergency
- 462.675 (70cm) - GMRS emergency channel 20
Once set up, connect your antenna and give it a test run.
Summary
Now, while I don't like the finish of the top surface, nor the fit, I think this will be operational for what I need, and I secretly think this is awesome. I'm hoping to surround the top plate with weather stripping, and put some custom gaskets beneath the switch and power bezels for a bit more moisture-sealing, but with the gaps under the radio faceplate itself, this is definitely NOT water tight. I'd like to revisit an antenna (if I can find a purple pipe wide enough to protect the antenna as well as act as a bit of a stand) to see if I can get that a bit more appealing.
With all of these prints together, it was time to assemble the whole thing.
And with that, we have a "hammo can" (portable base station) for emergency use!
