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__ T_YP_E_l_6_08_-A_1 M_P _E_D_A_N_C_E_B_R_I_D_G_E
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4.5
PHASE.COMPENSATION TECHNIQUES.
Several phase-compensating schemes are used to
achieve the required D and
Q
accuracy over such wide
ranges. The components used for this purpose are listed
below with a brief description of their function.
C13, C14--These capacitors compensate for the
inductance of the 1- and 10-ohm ratio-arm resistors.
C3, C3A, and L 1--These components are used to
make the standard resistor arm (R3) have a low phase
angle and a constant value over the frequency range in
spite of the rather large stray capacitance placed across
this arm by the bridge transformer and wiring.
C14,
CIS,
and C16--These capacitors are used to
compensate for inductance in the winding of the lower-
valued DQ rheostat (R4).
LA, LB,
CC,
etc, RA, RB, RC, etc on R1--The
inductors are used to compensate for the capacitance
placed across the whole variable arm by the wiring and
30
switches.
The inductors have enough resistance to re-
quire resistors in parallel to restore the correct over-all
value. See Figure 4-3.
Capacitors are used to compensate for the induc-
tance of the vernier potentiometer R2, and the resistors
are used
to
adjust its value to better than ± 1/4% of full
scale.
WIRE-WOUND RESISTORS
COMPENSATING INDUCTORS
R'/ R / : '
L
<
R
R
R
""' L
'""--
~
RESISTORS TO COMPENSATE FOR
RESISTANCE OF INDUCTORS(R L )
Figure 4-3. Phase compensation of
centades.
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