It has been shown that there are intergranular contacts of an order of
coherent length in size in the high-T(c) ceramics. This fact enables
a successful development of one-contact rf-SQUIDs operating at liquid
nitrogen temperature. Signal and noise characteristics of these yttriu
m ceramic SQUIDs are given. Some aspects of these SQUIDs application f
or magnetic cardiography and sensitive galvanometry are reported.