  We replace the standard model scalar doublet by a doublet of vector fields
and generate masses by dynamical symmetry breaking. Oblique radiative
corrections are small if the new vector bosons ($ B^+$, $ B^0 $) are heavy. In
this note it is shown that the model has a low momentum scale and above $
\Lambda \simeq 2 $ TeV it does not respect the perturbative unitarity. From
tree-graph unitarity the allowed region of $B ^+ (B^0) $ mass is estimated as
$m_{B^+} \geq 369 \hbox{GeV} \quad (m_{B^0} \geq 410 $ GeV) at $\Lambda= 1 $
TeV.
