HP 416A - Page 72

Tracking - The check on meter tracking should be performed follow-
ing the calibration and tuning eye adjustments . The test equ i pment is con-
nected as shown in Fig . 18 , and circuit conditions will be the same as detailed
in paragraph 1 of the tuning eye adjustment .
NOTE : The DB scale on the Model 416A meter is calibrated in power
ratios (10 log~) of the rf inputs to the square - law detectors,
P2
whereas the DB calibration of the Model 350A (or B) is based
on power ratios proportional to the square of the voltages
(20 log E1). Therefore a 2 db setting on the Model 350A
E2
(or B) corresponds to 1 db on the Model 416A meter scale.
Scale Tracking :
1. The RANGE switch on the Model 416A is at the 0 DB 100% position.
2 . To check scale tracking , attenuation inserted by attenuator #2 is
increased in 4 - db steps . The level of reflected voltage , as indicated by the
Model 416A meter should drop in 2 - db steps, as i ndicated in the following
table.
Atten . #2
Model 416A Meter
Setting
Reading , DB Scale
0 DB
0
4
DB
2
8
DB
4
12 DB 6
16 DB
8
20 DB 10
3. Return the setting of attenuator #2 to 0 DB .
Range Tracking :
1. · To check the range track i ng , attenuation of the reflected voltage
is increased at attenuator #2 in 20 - db s t eps . The Model 416A meter indic -
ation should follow in 10 - db steps the changes in attenuation , as indicated in
the following table .
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