Boonton Electronics 71A, 71AR - Page 16

3.3.2.1 111000 pF ZERO" Adjustment
The 111000 pF ZERO" control is located at the rear panel.
Its setting is checked by switching to the 1000 pF range
and, with no specimen attached at the IITEST
If
terminals,
observing the rest position of the pointer. If it does
not read zero, follow the adjustment procedure outlined
in paragraph 3.1.4, (f) and (g).
3.3.2.2 IICOMP ADJ
II
Peaking Adjustment
Prior to measuring at the IITEST
II
terminals, the IICOMP
ADJ" peaking adjustment should be performed as follows:
(a) Attach any terminal adapters or connectors to be
used for subsequent measurements to the IITEST
II
terminals and set the "RANGE" selector to the
1 pF range.
(b) Adjust the "c ZERO" control for a reading of
approximately 75% of full scale.
(e) Adjust the IICOMP ADJ
II
control for a maximum
reading. (Readjust the "c ZERO" control to
keep deflections on scale if required.)
(d) After peaking, zero the pointer using the
lie ZERO" control.
Once adjusted, the "COMP ADJ
II
control need not be re-
adjusted (although periodic checking during extended
periods of operation is advisable) unless some change
in either the method of connection or the nature of the
test samples substantially affects the stray capacitance
from the "HI" post to ground. In such cases, readjust-
ment pf the "COMP ADJ" control is required.
The above "COMP ADJ" adjustment procedure will suffice
for the majority of measurements at the terminals for
all ranges. However, to obtain the greatest possible
accuracy when measuring high Q (>10) components on the
1, 3, 10 or 30 pF range, and when the test sample has
significant capacitance from the IIHI
JI
post to ground,
the following procedure should be follows:
(a) Attach whatever terminal adapters or connectors
are to be used in subsequent measurements to the
"TEST" posts and connect a specimen typical·of
3-4
7lA