Thread: School me on walkie talkies

Keen to learn more about these. We want a couple to use for when the Mrs joins me dark and early on the farm and so the kids can let us know when they are awake. From the cowshed to the house is 700m odd, a small stand of trees, a hedge or a concrete sided silage bunker obscuring some or all line of sight. My tire kicking so far makes me think 5 watt handheld units might be the way to go because then they will be powerful enough to reach home if we do disappear down the back of the farm. Bonus points for keypad lock so the kids can't talk to other channels too I suppose. Any brand in particular stand out, familiar with names like GME and Uniden but seeing Baofeng cropping up in searches too, are they junk?