Construction Project: HammoCan
A time comes in every Ham’s life, when they need to be free of the same four walls, free from the QRM and seek new ground(planes). Fortunately for most Hams, we have the option of running our equipment while out and about, whether you choose to go /P or operate while /M. When your time comes you start to think of the possibilities as well as the new challenges you will ace. One of those challenges will be how you choose to transport your radio, depending on whether you want to operate while on the move or potentially have the luxury of setting up your shack when out in the wilderness (or your local park).
With the idea of operating your radio away from your QTH, certain questions arise: –
* Where will you place your radio when activating?
* How do you intend to power it?
* Which radio or radios do you intend to take?
* How do you intend to carry or transport your kit along with all the accessories such as coax,
batteries, antennas etc. etc.?
You could could simply get away with storing your kit in bag or case of some description and then assembling it when on location. However, my preference at this moment is to have my rig setup in a ready to go and ready to run case. This would ultimately be a portable box with my transceiver mounted, power incorporated and can be placed on a flat surface, be it a park bench, picnic or camping table or maybe the boot of a car, with minimal setup required and ready to get on the air.
It was time for me to start looking into ideas. On my hunt, there was naturally plenty of different designs from other Ham’s with similar ideas, as well as units which had been manufactured for the purpose of operating radio while portable or mobile, such as military packs, flight cases and so on.
I narrowed my search specifically to DIY Go-Boxes.
One in particular that caught my attention was that of WA4A (as shown on his QRZ page). My intention was to use my Xiegu G90, which is a compact SDR based HF transceiver and WA4A’s (Robert) design looked ideal. I wanted to find out more, so I decided to reach out to Robert.
I made contact by email and Robert was kind enough to share with me the details on his DIY Go-Box. My main curiosity was what Robert had used for the chassis or case. Robert explained that it was from a 1960s Tektronix Type 111 Pretrigger Pulse Generator. The generator was from a series of Tektronix oscilloscope accessories.
Robert kindly shared more on how he constructed his Go-Box to contain his FT-817 along with a 9A/hr LiFePO4 battery, LDG antenna tuner and Signalink sound card.
This was impressive and it gave me a possible path to follow when designing my go-box and a possible form-factor to consider
With Robert’s idea in mind, I started to search on eBay for second-hand oscilloscopes and similar lab testing instruments, in hope that I would find one of an ideal size and form-factor
I eventually bought a vintage oscilloscope for around £20. Once I had stripped out the inside of the oscilloscope (with the help of M7EAO (my Dad)) and removed the panel switches etc. I then began looking at how I may fit my G90 along with a 14A/hr lead-acid battery. Unfortunately, I soon realised that this box as it was, was too small for my needs and it will end up too cramped inside.I was once again looking for similar cases but of a larger size. As you can imagine, there were many others of different shapes and sizes but none that really appealed to me or were within a practical price range.
I went back to looking for other Go-Box ideas while keeping in mind the fact that if I end up with too small a case, I will ultimately end up limiting my options further down the line, for example, if I decided I wanted to use a different radio or possibly to have more than one radio in my Go-Box.
Heading down this line of thought I came across what is termed a shack-in-a-box and realised that the possibilities can go far beyond what I was initially aiming for.
My scope of ideas began to narrow again when I came across designs using surplus ammunition boxes aka ammo-cans. Searching for ammo-cans online was not difficult, with multiple sellers offering these at competitive prices and varying sizes and construction.
I had to make a decision and finally settled on a large ammo-can, roughly sized at 25x26x49.5cm, purchased on eBay. This was definitely larger than I was originally intending but I could see it had better potential for my overall plan. The ammo-can is very well built, with a removable lid and carry handles. I was not too concerned about its condition; overall it is in very good condition considering it was a surplus ammo-can, plus I very much liked the patina
I then began considering the layout within the box and seeing as I still had the case from the
oscilloscope, it seemed a waste to not consider making some use of it
I played around with different positions of the radio, battery and so on, before I made a final
decision. The decision of the layout was based on how I want the ammo-can to be positioned when operating my radio (horizontal) and how I planned to mount and fix the various components within.
Fortunately, the Xiegu G90 can run with its head detached using a serial-type cable. This would prove to be useful here, as it would provide further options on how the radio could be mounted within the ammo-can, as opposed to me having to have the entire unit being mounted in one lump, which could then limit my options on how the other components would then have to fit around it.
I played around with the idea of the oscilloscope case providing a compartment within, perhaps to house the battery and fuse box however, the overall length of the oscilloscope case was a touch too long, therefore it would have to be modified. I removed the rivets which attached the sides of the oscilloscope case to its base and rear, then shortened the length of its base. As shown in the last picture here, it now fits within the ammo-can and will be used to ‘cradle’ the battery.
The fuse box is simply an automotive fuse box purchased from Amazon and it accepts standard-size blade fuses. Using the fuse box will make it much easier when it comes to the wiring of all the components, as opposed to using in-line fuses and having all the cabling in a much less tidy fashion.
With the head removed from the G90, it fits nicely within the ammo-can widthways, with the required space at either end for the coax and other cabling that needed to be attached.
Now it was time for the fun to begin – the construction
I purchased 2 sheets of 2mm aluminium
checker-plate sized at 250x500mm. This is
sturdy aluminium, easy to work with and looks the part.
The aluminium will be used to make an
instrument panel, a back plate and a dividing wall. The instrument panel will have the G90 head and a V/UHF radio mounted, along with the switches, sockets and dials. The back plate is to provide a surface to mount various components within and in turn, reducing the number of holes drilled into the ammo-can itself
The ‘Hammo-Can’ began to start taking shape very quickly. I firstly cut a sheet to shape and size to attach to the bottom/back as the backplate and another piece to create a wall to divide one area for the battery and fuse box on the left, with the radios and other components on the right. The back-plate was attached using bolts and the diving wall attached to two cut lengths of angle (top and bottom), which in turn were attached to the inside of the ammo can, using pop-rivets.
As mentioned before, the back-plate is to provide a surface for components to be mounted and the first to be attached was the fuse box, attached simply by using self-tapping screws. I have placed it at a height where it will be above the battery and have enough spacing around it for the cabling to be terminated to it.
The modified oscilloscope case, now battery cradle, slots nicely in the left section. I have
mounted what is to be the main power switch on the face of the battery cradle. The power switch has a sprung, hinged safety cover (aircraft style) which is to prevent it from being switched on when in transit.
Next, I cut the aluminium to serve as the instrument panel which is hinged at the bottom. This panel can then be opened to allow access to the components and cabling behind
Before cutting the holes, a template was made using software for the instrument panel layout. Each component was carefully measured and then placed on the template so I could then best decide on the layout. The template was then printed and cut, then placed on top of the aluminium panel, with each hole then marked for cutting. All panels and holes for this entire build were cut using basic hand tools; the holes were either drilled or cut using a hole-saw and the panels and rectangular holes were cut using a jigsaw. Once the panels and holes were cut, each one was cleaned up by filing and sanding. The circular components were going to be fairly straight forward to attach to the instrument panel however, I had to think how I would mount both of the radios.
Using the existing screw-holes in each radio, I constructed some brackets from some aluminium angle, which would allow the radios to be directly mounted to the instrument panel. Again, each piece was measured, cut and drilled.
This is the Leixen VV-898 V/UHF radio. I made use of the existing holes used to attach the mount it comes with, that is often used to mount the radio in your car
Next was the G90 head. Nice and easy, measured cut and drilled, again making use of the
existing mount-holes it has which are used to secure it the the radio’s body
The harness for the 12v battery was cut and shaped to allow room for a 14A/hr battery and keep it secure. I also wanted space above the battery for cabling and switches etc.
Again, everything was taking shape very nicely and I was very pleased with how it was all fitting together. With all the metal work done and polished up, it will soon be time to move onto the wiring however, I still needed to work on a method for the battery harness to be attached and secured within the Hammo-Can. I wanted the battery harness either to be hinged or to have a mechanism to allow it to slide in and out like a draw, allowing access to the battery and the fuse box behind it. I finally settled on a draw-like idea but it will still need to be possible to completely remove the battery harness, to allow access to the fuse box and wiring, as well as being possible to have it secured to prevent it from shifting when in transit
With some thought, I purchased some T-Track (or Mitre track) and T-Nut sliders. This is often used on the likes of table-saws to allow you to attach sliding guides and guards, which you then secure in place before making the cut. With this I will be able to create a mechanism where the battery harness can slide in and out and also be able to tighten the fastening bolts its attached to, which will keep the battery harness in place, locked-in and secure. The T-Track and T-Nut Sliders were purchased from Amazon and cut to size, then the sliders attached to the inside of the hammo-can using M8 bolts and the tracks attached to the battery cradle. My idea worked and I was able to tighten and loosen the bolts fastening the sliders, in order to remove and secure the battery harness.
Now to the wiring. I started by attaching the fans, switches and sockets to the instrument panel. Pictured above are the switches, again with the safety covers however, I later decided that these covers were possibly a little over-kill on this panel and not necessary, so they were later removed. The cabling was very easy and with the space I had inside, there were no excuses in keeping the wiring neat and tidy.
Within the main section, you can see on the back panel the rubber feet and latching loops, which will be used to secure the body of the G90, where this radio will be strapped to the back with its speaker facing towards the instrument panel. The rubber feet are to reduce movement and vibration whilst the radio is mounted inside and when in transit.
Two holes were made in the dividing wall and grommets fitted within the holes, to allow the
cabling to run back from the main section to the fuse box. The blue socket at the top is a 50A Anderson connector. Yes, a 50A connector is definitely overkill for this build however, some of the cabling used in this build is from a scrapped APC UPS and these connectors which came with it, provided the possibility for the battery harness to be disconnected when it is to be removed, as described earlier
With its lid on, it still mostly looks just like the ammo-can it once was, apart from the few bolts and rivets now visible on the outside. On the side (actually the base when its in its operating orientation) you can see four large bolts which are attached to the rails, securing the battery cradle
With the lid removed, there is space for the radio mics and my Morse key. The battery harness works mostly as well as I had hoped it would, where it can be removed and secured. Further modifications were made to the front of the battery cradle by adding a 12v power input, a main fuse and a handle at the base to allow you to move the battery harness in
and out. The main power switch is SPDT switch. This is so that, when the power switch is in the ON position (cover open, switch in UP position), it uses the internal battery. When the switch is in the OFF position (switch down and cover closed), it will accept the power connected to the power input poles
The battery harness has the other end of the Anderson connector which connects inside the Hammo-Can (as shown in the picture below).
The Hammo-Can powered on with its green LEDs and radios also powered on. The four switches on the instrument panel allow you to power-on he LED lights (from the left, switch 1), the two cooling fans (switch 2), the Leixen VV-898 V/UHF radio (switch 3) and the Xiegu G90 HF radio (switch 4).
The two SO239 sockets have dust caps that unscrew and hang out of the way. The top SO239 socket is for HF radio (the G90) and the bottom socket is for V/UHF radio (the Leixen). There is also a 12v power outlet and two USB sockets, to allow me to power other devices I may use when working my radio. The two cooling fans and the grills which cover them, were rescued from a scrapped smallform-factor PC, and were the perfect size for my build, provide plenty of ventilation for cooling, as well as serving as sound-holes for the radio speakers inside. You may also notice a smaller socket just next to the G90. This is a 3.5mm stereo-jack socket which I use to connect my Morse-key to the G90.
The instrument panel is secured shut using two captive thumb-screws at the top of the panel, while hinged at the bottom. With the instrument panel open, you can access the various components and cabling mounted to the panel. On the left, you have a 15v DC volt-meter and a 30A DC ammeter. I intend to swap out this ammeter when I can, possibly with a 10-15A DC ammeter, as the current ammeter was all I could get hold of for now and it is a little overrated for this build. The rear of the G90 head has its serial cable which then connects to the G90s body. The SO239 sockets are patched into the corresponding radios using coax patch cables and right-angle adapters.
The above picture provides a better view of the G90’s body mounted or strapped to the rear
panel, as described earlier. You can also see my attempt of keeping the cabling neat and tidy
within, using ties and cable sleeves.
Above shows the inside of the left compartment wit the battery cradle completely removed,revealing the fuse box. At the base are the rails that the battery harness slides onto.