HP 334A User Manual

Section IV
Model 333A/334
4-33. Refer to Figure 4-5 for the phase relationship
of the bridge error signal andreference voltage at the
base of A5Q4. The shaded portions of the error sig-
nals (band c) indicate that part of the error signal
which contributes to the dc lamp control voltage. As
indicatedind, any error signal that ie 90° outofphase
with
the reference does not affect the dc lamp control
voltage, because equal amounts of the positive and
negative portions are passed.
4-34. The operation d the reactive branch control
loop
ie similar to that of the resistive branch. The
phase
delay circuit, A5Q15, A5Q16, S4AF and
S4C1 through S4C5, shifts the reference voltagc
90°, aa shown in Figure 4-5f. This makes the detector
A5Ql2 sensitive to components of the bridge error
signal that are 900 out of phase (g and h). The outpui
of the lamp driver, A5Q14, controls the brilliance of
A6DS2, which varies the resietance of A6V2 through
A6V5 to tune the branches of the reactive leg. Deck
AR of the FREQUENCY RANGE switch, 54, switches
A5R56 in parallel with A5R55 on the top three fre-
quency ranges. A6DS2 will become brighter, and lower
the resistance
of A6V2 through A6V5, makingvariatio
45' 135' 225' 315'
a
Ref. signalfor Resistive
Detector
(A564)
b
Resistive Error signal
in phase with reference
at bridge
Resptive Error signal
180 out of phase
d
Reactive Error signal
30 out of phase (Results
in no output from Re-
sistive Detector)
e
Error signal, reactive
leg detuned, resistive
.eg unbalanced
f
Ref. signal for Reactive
Detector
(A56 12 b
Reactive Error signal
in phase with reference
at bridge
Reactive Error
out of phase
h
signal
i
Reptive Error signal
90 out of phase(Results
in no output from Re-
active Detector)
Error signal, Reactive
leg detuned, Resistive
leg unbalanced
45' 13s' 225' 316'
Figure 4-5. Reference and Error Phase Relationship
4-4

HP 334A Specifications

General

Brand	HP
Model	334A
Category	Measuring Instruments
Language	English