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Model 415E
Section III
Paragraphs 3-22 to 3-24
transmission line as a shunt admittance which increases
(disturbing the transmission line more) as the probe
penetrates farther. To find out whether a given probe
penetration is too great or not, measure SWR, then
change probe penetration and remeasure SWR.
If the
second reading is different, the probe is penetrating
too far and loading the transmission line significantly.
scale). Now move the probe toward a minimum. If the
meter drops below 3.2, rotate the RANGE-DB switch one
position clockwise and read on the 3.2 to 10 SWR scale.
If the pointer drops below this scale, rotate RANGE-DB
switch one more position clockwise and read on the 1.0
to 4 scale and multiply by 10.
This pattern continues
for still higher SWR readings.
3-22. PROCEDURE.
3-23. MODERATE SWR. The scales of the 415E are
calibrated for reading standing wave ratio directly from
the meter. Set the slotted line probe at a voltage max¬
imum and adjust the gain of the 415E with the RANGE-
DB, GAIN, and VERNIER controls (EXPAND switch to
NORM) for full scale deflection (1.0 on the 1.0 to 4 SWR
3-24. The DB scales can be used for a standing wave
ratio measurement by setting the 415E to full scale at
a voltage maximum, then turning the RANGE-DB switch
clockwise for anon scale reading at a voltage minimum
and noting the difference in DB readings at the maximum
and minimum. A DB reading is obtained by adding
RANGE-DB switch setting and meter indication.
02152-2
Figure 3-5. Expanded Section of Figure 3-6
3-5
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