[High-frequency transistor tract for UHF therapy device].
The paper deals with the specific features of construction of a common circuit and individual units of high-frequency transistor tracts for physiotherapeutic UHF apparatuses whose design is a possible way of conversion of radioelectron equipment. The design of UHF tracts gives rise to some radio engineering problems due to the low output resistance of bipolar transistors and to the operational characteristics of physiotherapeutic equipment and, as a result, the load of the tract is a two-conductor long line loaded with complex resistance whose active part changes slightly and the reactive one varies very greatly. The structure of a high-frequency, which transfers power from the generator with external excitement to the active part of complex load by changing its reactive part in the wide range, was analyzed. It is shown that for reliable operation of the UHF apparatus, its tract should have a multichannel structure with subsequent summation of the power and automatic compensation of the reactive component of alternating load. This provides a measuring mode for the power connected to the patient. The tract structure in question may serve the basis for the designing transistor physiotherapy apparatuses of average and high power (Poutput = 50-400 W).