manual control must be continuously adjusted as the aircraft changes altitude. B. Turn the range switch (S-1) from "OFF" to "SET". This connects the batteries and places the aircraft radiation recorder in the circuit as a voltmeter indicating the B plus voltage. C. Adjust the "B 0.70 ma. Since of the recorder which may cause SET" control bringing the recorder reading to this setting is critical, the paper in front pen should be tapped, to overcome pen friction erroneous readings. D. Start the recorder chart drive. E. Turn the range switch to a scale giving a convenient reading on the airoraft radiation recorder or cantrol box meter. An external voltmeter cirouit is box meter (See Section 3.2.1) required to drive the control The ground-level radiation-intensity signal-voltage is a combination of the aircraft radiation signal and the altitude compensation voltage. Therefore it is possible to have a reading on scale even when measuring a radiation intensity which is less than the minimum value that can be measured on that particular scale. Jf there were no altitude compensation the recorder would read below scale, but at high altitudes there might be sufficient altitude voltage introduced to drive the recorder on scale. As an example, this condition would occur if the aircraft were flying at 500 ft. (fa-11.5) and the radiation intensity at the aircraft was 0.05 mr/hr. This corresponds to a three foot intensity of 0.58 mr/hr and would be indicated as such if the A scale is used. However, if the B scale is used the recorder will indicate 0.27 mr/hr (0.14 ma). To prevent this from occuring the operator should always check to make sure he is on the lowest range scale (A,B,C, or D) giving an on scale deflection on either the three foot level recorder or the meter on the control box. - 26 -