  Dynamic magnetic susceptibility, $\chi$, was studied in several intermetallic
materials exhibiting ferromagnetic, antiferromagnetic and metamagnetic
transitions. Precise measurements by using a 14 MHz tunnel diode oscillator
(TDO) allow detailed insight into the field and temperature dependence of
$\chi$. In particular, local moment ferromagnets show a sharp peak in $\chi(T)$
near the Curie temperature, $T_c$. The peak amplitude decreases and shifts to
higher temperatures with very small applied dc fields. Anisotropic measurements
of CeVSb$_3$ show that this peak is present provided the magnetic easy axis is
aligned with the excitation field. In a striking contrast, small moment,
itinerant ferromagnets (i.e., ZrZn$_2$) show a broad maximum in $\chi(T)$ that
responds differently to applied field. We believe that TDO measurements provide
a very sensitive way to distinguish between local and itinerant moment magnetic
orders. Local moment antiferromagnets do not show a peak at the N\'eel
temperature, $T_N$, but only a sharp decrease of $\chi$ below $T_N$ due to the
loss of spin-disorder scattering changing the penetration depth of the ac
excitation field. Furthermore, we show that the TDO is capable of detecting
changes in spin order as well as metamagnetic transitions. Finally, critical
scaling of $\chi(T,H)$ in the vicinity of $T_C$ is discussed in CeVSb$_3$ and
CeAgSb$_2$.
