Portable Repeater Project - Power

In the past I’ve built go box style setups which included internal batteries. The goal, in my view, was to have a setup where you bring it to the site, open it up, hook up an antenna, turn it on, and you’re QRV. No muss, no fuss.

But my thinking no longer runs in that direction. Internal batteries of substantial capacity using SLA batteries just impose too great a weight penalty. It’s no good portable repeater that isn’t really portable because it weighs too much to move around.

The portable repeater will consist of two mobile radios, two duplexers, some cabling and electronics to glue it all together, and whatever case it gets put in.

The radios weigh about a kilo apiece. Duplexers tip the scale at 1.7 kg. The case is specced at 5.56 kg, plus two shelves at 0.5 kg apiece. So right there we’re at 12 kg. Throw in another kilo for cables, electronics, connectors, etc. and we’re suddenly looking at nearly 14 kg or 30 lbs. That’s still portable but it’s at the upper end of the range I think is acceptable (and weight reduction is a big reason why I’m still penciling out lighter case solutions - note that half the weight is the damn case!).

So the power supply will, I think, be external. I have in mind an idea I’ve toyed around with a bit - basically a battery box with a built-in 120VAC to ~14VDC power supply to either supply power directly, charge the built in LiFePO4 battery, or do both simultaneously. This arrangement means it can be plugged into 120VAC mains power, run the repeater and charge the battery, and then when the power gets cut, simply switch everything to the battery. Remember, in emergency deployment, 120VAC power is likely to be a small genset, which might get run intermittently or which can’t be connected to the repeater continuously for some tactical reason (example: we need the generator to power the lights in the Triage tent until the sun comes up).

The total weight of the entire system isn’t reduced, but the general portable power box is useful in a lot of different situations, and splitting the weight into two units makes it all a lot easier to move around.

So basically the power considerations for the repeater itself are that it should offer power input as Anderson Powerpole connectors, and then distribution inside the case will also be done with a small Powerpole bus box (plus appropriate fusing). There isn’t a lot of stuff needing power (basically, two mobile radios and the repeater controller) but I’ve found over time that using powerpoles makes it easy to reconfigure things on the fly when you need to make a system be different from what you set it up to be. (Example: life suddenly got complicated. I need to power the transmitter from this big battery and the rest from this smaller battery.)

So I’m thinking some small RigRunner sort of business to do the powerpole distribution and the fusing, and I’m done with all that without a lot of dorking about.