  In this paper we compare the characteristics of pulsars with a high spin-down
energy loss rate (Edot) against those with a low Edot. We show that the
differences in the total intensity pulse morphology between the two classes are
in general rather subtle. A much more significant difference is the fractional
polarization which is very high for high Edot pulsars and low for low Edot
pulsars. The Edot at the transition is very similar to the death line predicted
for curvature radiation. This suggests a possible link between high energy and
radio emission in pulsars and could imply that gamma-ray efficiency is
correlated with the degree of linear polarization in the radio band. The degree
of circular polarization is in general higher in the second component of
doubles, which is possibly caused by the effect of co-rotation on the curvature
of the field lines in the inertial observer frame.
  The most direct link between the high energy emission and the radio emission
could be the sub-group of pulsars which we call the energetic wide beam
pulsars. These young pulsars have very wide profiles with steep edges and are
likely to be emitted from a single magnetic pole. The similarities with the
high energy profiles suggest that both types of emission are produced at the
same extended height range in the magnetosphere. Alternatively, the beams of
the energetic wide beam pulsars could be magnified by propagation effects in
the magnetosphere. This would naturally lead to decoupling of the wave modes,
which could explain the high degree of linear polarization. As part of this
study, we have discovered three previous unknown interpulse pulsars (and we
detected one for the first time at 20 cm). We also obtained rotation measures
for 18 pulsars whose values had not previously been measured.
