Tektronix 511 Instruction Manual page 24

the output of the main rectifier. To obtain
regulation and filtering, a regulator consist­
ing of V25 and V26 is used. This regulator
operates in the same manner as the +225
supply, using the regulated +225 as reference
voltage. Thus, if the +225 is not set at its
correct value, the +450 volt output will also
be in error.
In order to provide the+ and- 1500 volts neces­
sary to operate the CRT, an oscillator type
supply is used. Since the input power to the
oscillator comes from the regulated + 225 volts,
its output is not affected by line voltage changes.
The oscillator uses the6AQ5 tube, V31,ina con­
ventional Hartley circuit. A high-voltage second­
ary on the oscillator transformer supplies
Five rectifier tubes are used for the various
DC supplies necessary to operate the Type 511.
The +475 v supply takes its power from Tl,
via the 5U4G full-wave rectifier, V21. Condenser
input is used. L I2 and C66 provide additional
filtering to remove ripple voltage.
The +275 v supply takes its power from T2,
via the 5U4G full-wave rectifier, V24. C71
serves as input condenser with L13, C54, and
C47 providing the necessary filtering. C54 and
C47 are located on the video chassis.
A 6X5G rectifier, V25, with its cathode con­
nected to one side of the high-voltage winding
on T2 supplies a negative voltage of approxi­
mately 300 volts. The plates of V5 are tied to­
gether since it is used as a half-wave rectifier.
C72 is used as input condenser. To provide
regulation and additional filtering the gas-filled
voltage regulator tube, V26,is used. A relatively
constant voltage of 150 v is maintained across
V26. The 470 ohm resistor in series with the
output of V26 eliminates a tendency of V26 and
C21 (on the sweep chassis) to form a relaxation
oscillator.
The + 225 v supply which supplies most of the
critical circuits is obtained from the +475 v
supply via an electronic regulator. This utilizes
the 6L6, V29, as the series tube, the 6SJ7,
V27, as shunt amplifier, and the VR105 regula­
P A G E 3 - 8
approximately 1250 v RMS to the two type
1B3GT/8016 rectifiers, V32 and V33. Filament
voltages for these tubes are obtained from wind­
ings
frequency of the oscillator is fairly high (2KC),
a single .05 capacitor provides adequate filter­
ing for the +1500 volts. A filter consisting of
a .05 jif input capacitor, a 27K resistor, and
a .5 /if output capacitor is used on the -1500
volt supply because of the increased load and
need for an adequate bypass on the CRT cathode.
A variable resistor R165.2 (S/N2700 and up),
in series with the oscillator screen supply,
provides adjustment of the -1500 volt supply to
compensate for tube changes, etc. Procedure
for setting this adjustment may be found in
Section 5 .
POWER SUPPLY
(S/N101-454)
tor tube, V28, as voltage standard. To see how
this circuit works consider what happens when
the output voltage on the grid of the shunt
tube, V27, increases, since its cathode is held
steady by the regulator, V28. This causes its
plate current to increase and thus lower its
plate voltage. V27,s plate is connected to the
grid of V29, the series tube. The increased
bias on V29 results in an increase in its in­
ternal resistance and therefore a decrease in
the output voltage. The reverse action takes
place when the load increases or line voltage
decreases. Thus the output is held constant
within one volt for a +or-10% change in line
voltage and such load changes as occur with var­
ious
effectiveness of the regulator to ripple and rapid
changes of load the condenser , C75, couples the
grid of V27 directly to the output. So that varia­
tions in tubes, etc., may be taken care of,the
potentiometer, R167, allows adjustment of the
output voltage.
supply via the 6V6GT series regulator, V30.
V30 acts as a cathode follower and since its
grid is taken from the regulated + 225 v supply
via the voltage divider R170 and R171, it tends to
maintain the cathode at a constant value regard­
less of its plate voltage. This type of regulator
is not as perfect as the type used in the + 225 v
supply, but is quite satisfactory as used here.
The filaments of V29 and V30 are from the
T Y P E 5 1 1 - C I R C U I T
on the oscillator transformer. Since the
sweep duty cycles.
The + 125 v supply is obtained from the + 275 v
D E S C R I P T I O N
To increase the