Baby monitors (Sherwood TN2)

I have 2 Hello Baby HB30 video baby monitors. Giving them away as the signal drops out in certain places in my house. The second one was sent to me by the manufacturer as a replacement but it’s no better. It’s a newer version but only has USB connectors so requires USB plugs or USB power strips. The first one (the older model) has 3-pin plugs. Can go separately or together.