(c) Turn HI volt switch on signal source to off.
(d) Turn on power meter calibrator by setting FUNCTION switch to current
off; then apply a substitution current by setting FUNCTION switch to substitute
and adjusting current controls until reference reading is obtained on digital
(e) Note and record indication on digital voltmeter.
On the 0.01-,
0.03-, 0.1- and 0.3 mW ranges this is the substitution current IDC in mA. On
all other ranges multiply by 10 to obtain IDC in mA.
(f) Disconnect thermistor mount from thermistor mount cable.
thermistor mount cable between H-P 431C and H-P 8402B calibrator resistance
standard connector. Set H-P 431C power meter to null position.
(g) Set H-P 8402B calibrator thermistor resistance control to -0.5% and
mount resistance to correspond to resistance and type of thermistor used.
(h) Set H-P 431C range switch on H-P 8402B clockwise until the power
meter changes from zero reading to a stable reading above zero. The operating
resistance of thermistor (Rd) is nominal value indicated on mount label plus or
minus correction indicated by setting of thermistor resistance switch.
(i) Calculate power in mW from this formula