Boonton Electronics 71A, 71AR - Local Capacitance Measurements

3.2 capacitance Measurements
With the front panel IIL-C
II
selector in the "C
II
position~ the
Models 71A and 71AR measure the "direct" capacitance of the
test specimen. (The instruments ignore stray capacitance
from the "LO" post to ground. Up to about 100 pF of capaci-
tance from the "HI" post to ground can be nulled by adjust-
ment of the "COMP ADJ" control. As a result~ the Models 71A
and 71AR measure only the capacitance appearing between the
"HI" and "LO" terminals.)
The measurements may be made either at the "TEST" terminals
or remotely by connecting the specimen or test fixture via '
coaxial cables to the "TEST" terminals. By use of both the
"DIFF" and "TEST" terminals differential capacitance measure-
ments may be made within certain limitations.
3.3 Local Capacitance Measurements
3.3.1 Connections for Local Measurements
While the capacitance connectors of the Models 7lA and 7lAR
are intended primarily for attachment of coaxial cables~
tests may readily be made locally by connecting the speci-
men directly to the te~inals. A pair of Type UG-1090/U
or comparable BNC-to-binding-post adapters are particularly
convenient for this purpose~ although for quick measurements
the leads of the component may be simply inserted in the
center receptables of the BNC terminals.
NOTE
If any length of coaxial cables is used for connection~
even if they are only a few inches in length~ the
measurement is considered not local~ but is remote and
the instructions of paragraph 3.4 apply.
3.3.2 Checks and Adjustment Prior to Making Local Measurements
There are three controls whose adjustment should be checked
before measuring at the terminals of the Model 71A or 71AR:
(a) "1000 pF ZERO"
(b) "COMP ADJ
II
(c ) "C ZERO"
3-3
71A
d