Fluke Biomedical 35080B - Manual (Page 13)

Operation
Oscilloscope Zero and Offsets
2
2-3
Figure 2-1A and 1B. Suggested Oscilloscope Settings for Use with the Wide Range Filter Pack
(37617)
As an alternative to reading directly in kV, the output of the Model 35080B kVp Divider may be read
directly in volts. The formula below is used to calculate the kV:
kV = Model 35080B voltage x 100 + ZERO kV
Example: A peak voltage of 0.300 volts is read. The ZERO kV of the Wide Range Filter Pack (37617) is
40 kV. Therefore:
kV = 0.300 x 100 + 40
= 30 + 40
= 70 kV
2.5 Geometry of Setup
The filter pack is aligned on the beam center, with the long axis of the Model 35080B kVp Divider
perpendicular to the x-ray tube axis, and the beam normal to the tabletop (see Figure 2-2). The x-ray
beam must be large enough to cover the active area of the filter pack. Distance is not critical, but a 22-
inch distance from focal spot to kVp divider is suggested.
The kVp divider must be inverted for under-table x-ray head evaluation (refer to Figure 2-3). Again, the
filter pack should be on beam center, perpendicular to the axis of the x-ray tube and the beam normal to
the table. The beam area must be large enough to cover the active area of the filter pack.
In positioning the kVp divider, the long axis of the instrument should be perpendicular to the x-ray tube
axis to eliminate “heel effect.” The beam must strike the filter pack side of the kVp divider; the unit is
designed to be turned over for under-table x-ray heads. In setting the x-ray generator, 200 mA at 22
inches is recommended, but the limits of operation allow higher or lower settings and distances. Refer to
Section 1-4, Specifications, for low current limits.
After correctly positioning the kVp Divider, connect the oscilloscope, place the kVp Divider in the “RUN”
mode and make an exposure.