A simple plasma source using microwave breakdown near cyclotron resonance in a low pressure gas has been developed. It consists of a tapered glass tube inserted through a waveguide that is terminated by a tunable short. By suitable choice of the degree of taper, the problem of strong temperature inhomogeneities (and sometimes hollow plasmas) frequently encountered with ECR plasma production can be overcome. Using relatively low microwave power levels, <3 W, the following ranges of electron temperatures and densities have been produced: 2 <Te<8.5 eV and 3 × 109<Ne<4 × 1010cm−3(the density is power limited).