first referring to fig1 wherein a prior art transponder 10 consisting of a closed loop housing 11 attached to a power transmission line 12 by means of a housing clamp 13 is shown transponder 10 includes a transmitter and power supply housing 14 forming part of the loop housing 11 and a radio frequency antenna 15 which is secured to transmission line 12 by means of an insulated antenna clamp 16 antenna 15 generally extends for approximately 150 inches to antenna clamp 16 the loop housing 11 is generally an oval shape in the order of two by four feet the thermocouple 6 is located approximately 36 inches from hub 13 and held in place by clamp 16 because of the mechanism employed for attaching antenna clamp 16 and housing clamp 13 transmission line 12 must first be de energized in order not to cause any electrical shock hazard to the installer the power supply and transmitter circuit 17 shown in fig2 is contained within transmitter and power supply housing 14 in fig1 circuit 17 is an analog circuit which includes a modulator unit connected to a temperature sensor located within housing clamp 13 and contacting transmission line 12 to determine the temperature of transmission line 12 during periods of operation a standard radio frequency transmission circuit is included within the transmitter and is connected to antenna 15 for transmission to a nearby receiver generally within fifty feet of transmission line 12 the power supply within circuit 17 is a conventional miniaturized power supply which derives its power from the electricity generated within loop housing 11 which intercepts a portion of the air flux or magnetic field emanating from transmission line 12 transponder unit 9 according to the invention can be seen by referring to fig3.