TB 9-6625-2050-35
NOTE
Ensure that multimeter input leads are isolated from chassis
ground when performing (7) below.
(7) Adjust multimeter to measure microvolts and connect positive and negative
input leads, respectively, to VCOMP and VRF connectors on rear panel of power meter.
(8) If multimeter indicates less than 400 microvolts, record indication and proceed
to (9) below. If 400 microvolts or greater, press and hold power meter FINE ZERO switch
and adjust COARSE ZERO control so that multimeter indicates 200 microvolts or less.
Record indication. Release FINE ZERO switch and proceed to (9) below.
(9) Round off indication recorded in (8) above to the nearest microvolt and record
this value as V0.
(10) Set TI POWER REF switch to ON (in) and record multimeter indication as V1.
(11) Disconnect multimeter negative input lead from the VRF connector on power
meter and reconnect to power meter chassis ground. Record multimeter indication as
VCOMP.
(12) Calculate the power reference oscillator output level (PRF) from the following
formula:
2 VCOMP (V1 - V0) + V02 - V12
PRF = _________________________________
Where:
VCOMP = value recorded in (11) above
V1 = value recorded in (10) above
V0 = value recorded in (9) above
R = value recorded in (3) above
CALIBRATION FACTOR = value for thermistor mount at 50 MHz
(13) If calculated PRF is not between 0.993 and 1.007 mW, perform b below.
b. Adjustments. Remove TI top cover and set TI POWER REF switch to ON (in) and
adjust LEVEL ADJUST A8R4 (model 436A) (models 435A and 435B) (fig. 5) so that
calculated PRF in a (13) above is 1 mW.
a. Deenergize and disconnect all equipment.
b. Annotate and affix DA label/form in accordance with TB 750-25.