Experiments are described in which the absorption and emission of energy at and near electron cyclotron resonance may be studied with simplified equipment. The magnetic field is measured by electron spin resonance, thus bringing out aspects of spin as well as orbital angular momentum; the magnetic field may also be measured by the radius of the electron orbit, rendered visible by low-pressure hydrogen. It is observed that, in a gas-focused electron beam tube, the frequencies of maximum electron cyclotron resonance absorption and emission (as determined by the zero crossing of the derivative of the line shape) are generally different from the frequency of electron spin resonance, and the frequency shifts are functions of electron beam current. The line shapes are asymmetric and are also functions of beam current. These effects are tentatively identified with plasma effects in the gas-focused beam.