SECTION V
MEASUREMENT OF C, I., M, AND Q
a. Heasurement of Capacitance: avoid high series resistance, which would have the
same detrimental effect on accuracy of indication
The Mcdel 59 can be used for measuring
as low shunt resistance. It is also well to bear
capacitance, if a standard inductance is available.
The coils of the 59 can be used as standards, and in mind the possibility of internal series induc-
reference to Figure 12 indicates directly the tance of the capacitor under test. This internal
inductance may alter the apparent capacitance con-
shunt capacity which must be used to resonate each
siderably.
coil to a particular frequency. In order to mea-
sure capacitances between 10 mUd. and 50 mmf., it
b. Measurement of Inductance:
will be necessary to purchase a spare 5 to 10 mc.
coil. Figure 13 shows the use of standard meller The Model 59 can be used for the measur-
#SRS cllps and one of the Model 59 coils in the ment of inductance with the aid of a standard
measurement of input capacitance of a vacuum tube capacitor. Close tolerance silver mica and cera-
and its associated socket. mic capacitors are generally available over a wide
range or values. Only the small units should be
NmE: Some Circuits may involve Capacitance
shunted by resistance; therefore the approximate used to reduce the self lndpctance of the Capacitor
standard. If necessary, the value of unknown
minimum permissible shunt resistance for each coll
capacitors can be determined as outlined above in
is indicated on Figure 12. Higher values of shunt
Section V(a) so that they can be used as standards
resistance will permit more accurate measuremente.
for the measurement of inductance. It is well
In the case of large capacitancss in the to avoid the use of large air dielectric type
range of 200 to lo00 mnfd., it may be necessary to capacitors because of their high inherent self
take precautions in securing good contact and thus inductance.
mmfd to the mlnlmum clrcult capacitance of the coll; therefore
one mmfd should be subtrsctod from that value read opposite the
resonant frequency of the chart, Figure 12.
18. |
ACEC
OTHERS
