eXact 100 - Meter;Output and Chopper Comparator Circuits

METER/OUTPUT CIRCUIT
The symmetrical 1КО square wave or DC
level is fed to the grid of output cathode
follower V55 from the plate of V5. Cath-
ode resistance of this stage is composed
of .05% resistors which proportionately di-
vide the output voitage,
A 0-200 va meter is connected across
the 0.5 VOLT output tap and monitors the
proportional voltage drop at this point.
This direct metering permits accurate re-
sults even under conditions of extreme
loading. Meter rectification is not need-
ed in the JKC position due to the excep-
tional symmetry of the waveform.
Since only half as much average current
flows through the meter in the 1КС posi-
tion as in the DC position, meter shunts
R70 and R71 must be switched in when in
the DC position. METER BALANCE ADJ. R72
compensates for slight differences in to-
tal meter resistance and standardizes the
output accuracy.
CHOPPER COMPARATOR CIRCUIT
The 60 cycle chopper comparator is con-
nected in such a way that the OUTPUT al-
ternately sees the UNKNOWN INPUT jack and
then the internal calibrator signal. Power
to run the chopper is furnished by 6.3V
taken from the pilot light/filament line.
In the NORMAL position, power is removed
from the chopper and the OUTPUT jack is
connected directly to the internal cali-
brator signal.
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