TM 11-6625-1614-15
Section III
Paragraphs 3-28 to 3-34
PRF is the pulse repetition frequency in pulses per
second (pps).
Suppose, for example:
t
1
=
t
2
=
K=
PRF =
10 microseconds
990 microseconds
0.55
1000 pps
To find K, assuming
/
= 2 kilohms and
t
l=10micro-
seconds:
R
o
/
t
l = 2 10° = 0.2. Location 0.2 on the
X axis of the graph shown as Figure 3-6, and reading
K where X and Y axes intersect the unmarked curve. If
the ratio of
R
o
/
t
l were greater than 1, multiply the
X and Y axes by 10, and use the curve marked ”R
o
/
t
1 and K each X10”.
Solving the expression for the multiplying factor,
Model 410C
3-28. NEGATIVE PULSES.
3-29. In the case of a 10 microsecond negative pulse
(
t
2) and a pulse repetition frequency (PRF) of 1000 pps,
t
l would be 990 microseconds. Thus T
o
/
t
1 would be
approximately 0, and from the graph it is seen that
K is approximately 0. The expression would then
reduce to
3-30. It can be seen that in the case of negative pulses
of short duration much smaller readings will be ob-
tained for an equivalent positive pulse. As a result,
large multiplying factors must be used and unless the
pulse voltage is large, these measurements may be
impractical.
3-31. MEASURING RESISTANCE (Figure 3-7).
3-32. Before making resistance measurements, power
must be removed f rom the circuit to be tested. Also,
make sure capacitors are discharged to eliminate any
residual voltage.
3-33. MEASURING DC NANO-AMPERE CURRENT
(Figure 3-8).
3-34. The Model 410C can be used to measure nano-
ampere leakage current in transistors and diodes. The
three most sensitive DC voltage measurement ranges
are used to measure DC nano-ampere currents.
.
.
3-4
