Radio Go-Box
For Portable HF Operations
This project was certainly more work than expected, but it was also a lot of fun. As usually happens with these kinds of things, I kept adding features as I went along. This is max-nerd stuff, for sure.
The goal was to have a compact, self-contained, self-powered 1.8-440 mHz radio setup for camping, emergency drills, and mountain-topping fun. Just add HF antenna (and a solar-panel), and you're on the air.
The original FT-450D in the box was recently swapped for the FT-991a. Even though the 991a covers 2m/440, I wanted a separate V/U radio, and the FT-7900 is another great rig. Naturally, everyone that builds a box like this will have their own favorites.
The internal battery is a Mighty-Max 18ah AGM (Amazon, $34), and it holds up surprisingly well with heavy transmit use on the 100w HF radio. Naturally, one would want to use a solar-panel for long battery life. And some radios maintain output power better than others when the 12v buss-voltage sags.
Voltage drops are an issue with radios pulling >20 amps, so I used #8AWG for all radio power-wiring. The negative (ground) buss is actually a piece of quarter-inch copper tubing (no voltage drop there!!). All radio power-cords are very short and the negative-side fuses removed.
Each radio has a switch to cut all power, as they pull phantom-juice even when powered-down. I used heavy double-pole 20-amp switches with both contacts wired in parallel, for 40-amp capacity.
The cool little digital voltmeter ($8, Amazon) is also switched, as it draws a small amount of juice. It's bright enough to see in full sunlight. I wanted one with .01v resolution, and this one is perfect. There is also an ammeter in series with the input to the (internal) solar charge-controller ($18, Amazon), so I can see what the solar panel is doing. It's fun to watch it "kick-on" (to about 5 amps) when you hit the PTT switch. A 100w panel will actually give you over an amp even under a full-overcast sky.
The box has it's own internal battery float-charger, and a 10v regulator (accessory-output) for charging H/T's. The other inputs/outputs on the back are +12v @ 20-amp accessory output (fused), solar-panel input, and a heavy-duty input for connecting an external deep-cycle or vehicle battery (if solar is not available). One can also connect a high-rate bulk-charger, if desired. I used banana jacks because I had them on hand, but most will opt for Powerpoles.
Both radios have external speakers (for obvious reasons). The small one for the VHF/UHF is an MFJ-281. The HF rig gets an Auvio full-range (Amazon, $38/pair). The Auvios are cheap but great comm speakers!!
The top of the box is covered with a 1/8" aluminum plate, which makes a perfect ground-plane for 2m / 70cm. Just screw-on your favorite dual-band antenna onto the SO-239 bulkhead connector.
The finished box is 16Hx19Wx12D, and tips the scales at a hefty 51 pounds (Weight-spec? What weight-spec? HaHa). I'll be using it until I can't lift it anymore!!
Caution: Batteries of this type with heavy currents are dangerous, and can easily start fires. So, I fused the livin' crap outta this setup. There are 10 fuses, plus a couple of schottky-diodes to prevent current flows in the wrong direction. And there is a 30-amp master fuse right at the battery.
I use this operating platform made out of 1/2" MDF at the "tailgating" position. It also makes a nice "table" for preparing meals. The camper-shell window give some shade if the truck is oriented properly. A 26" stepladder is just the right height for an operating chair. Quick 'n' Easy !!