IB he INSPECTING AND TESTING THE RADIOSONDE 
specified for the evaluator (see J§B2-9.1). If it does not fall within the 
specified limits or if the thermistor is broken, set the radiosonde aside 
and replace the thermistor with another of the same type at some con- 
venient time. If the replacement thermistor also indicates a value outside 
the limits, reject the radiosonde. 
2.9 Hypsometer. If the radiosonde is equipped with a hypsometer make 
the following test. No liquid is needed in the hypsometer for this test. 
After adjusting the recorder to receive the low reference signal at 95.0 
ordinates, join the black and green test leads to connect the hysometer 
thermistor to the transmitter. If a value greater than 94.8 or less than 
90.0 is received reject the radiosonde. (AF, N) Radiosondes rejected be- 
cause of defective hypsometers may be used for soundings for which high 
altitude data are not required. 
2.10 Humidity. The humidity circuit will be checked without a humidity 
element installed, After adjusting the recorder to receive the low refer- 
ence at 95.0 ordinates, connect the yellow andblack test leads. A signal 
of less than 5.0 but more than 2.5 ordinates should be received, after 
recorder corrections (if any) have been applied. Ifa recorder signal out- 
side these limits is received, reject the radiosonde. Short the humidity 
clamps and again connect the yellow and black test leads. A low reference 
signal (within +1.0 ordinates of 95.0 ordinates) should now be received; 
otherwise, reject the radiosonde. 
2.11 Relay Defects. Proper power supply voltage is necessary for 
satisfactory relay operation. Before rejecting a radiosonde for defective 
relay, the power supply voltage should be rechecked to make sure that 
the minimum voltage requirements are met (see Table B2-1). A defective 
relay, or one out of adjustment, may be indicated as shown below, when 
a hygristor is not in the mounting clamps and the clamps are not short- 
circuited. Do not attempt to adjust the relay, instead reject the radio- 
sonde, 
a. Temperature ordinate is received for both temperature and 
humidity. 
b. Less than 5.0 ordinates is received for both temperature and 
humidity. 
c. Audible signal is not received for temperature or humidity, 
or both. 
Touch the black and yellow wires at least ten times to determine that the 
relay is switching properly. 
I iL = (68) FMH#3 
