  We consider a finite but arbitrarily large Klein-Gordon chain, with periodic
boundary conditions. In the limit of small couplings in the nearest neighbor
interaction, and small (total or specific) energy, a high order resonant normal
form is constructed with estimates uniform in the number of degrees of freedom.
In particular, the first order normal form is a generalized discrete nonlinear
Schroedinger model, characterized by all-to-all sites coupling with
exponentially decaying strength.
