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The problem with a cable TV meter is that it is not calibrated to measure radiated fields. The meter scale on it will be calibrated either in units of voltage (mV, dBu, etc), or power (mW, dBm, etc). None of those units is a measure of field strength, such as µV/m.
(added later) I just did some calculations for the 100 MHz field strength that a typical, matched 1/2-wave dipole would need to see in order to produce a reading of 250 µV on a cable meter.
If the cable meter reads 250 µV in its 75 ohm environment, that means that a power of 0.0033… mW (-24.7 dBmW) exists in the measuring circuits of the meter (P = E^2/R).
A matched, 1/2-wave dipole would need to be immersed in a radiated field of over 32,700 mV/m in order to produce the amount of power needed by the cable meter to show a reading of 250 µV.