the signals to be mixed being applied between the same two electrodes

Full Title

Transference of modulation from one carrier to another, e.g. frequency-changing (H03D9/00, H03D11/00 take precedence; dielectric amplifiers, magnetic amplifiers, parametric amplifiers used as a frequency-changers H03F) > by means of discharge tubes having more than two electrodes (H03D7/14 - H03D7/22 take precedence) > the signals to be mixed being applied between the same two electrodes