INSTRUCTION MANUAL
MODEL 242
REGULATED HIGH VOLTAGE SUPPLY
WARRANTY
We warrant each of our products to be free
from defects in material and workmanship. Our
obligation under this warranty is to repair ‘or
replace any instrument or part thereof (except
tubes and batteries) which, within a year after
shipment, proves defective upon examination.
We will pay domestic surface freight costs.
To exercise this warranty, call your local
field representative or the factory, DDD 216.
795-2666. You will be given assistance and
shipping instructions.
REPAIRS AND RECALIBRATION
Keithley Instruments maintains a complete repair service and standards laboratory in Cleve-
land, and has an authorized field repair
facility in Los Angeles.
To insure prompt repair or recalibration serv-
ice, please contact your local field representative or the plant directly before returning the
instrument.
Estimates for repairs, normal recalibrations,
and calibrations traceable to the National Bureau
of Standards are available upon request.
MODEL 242 VOLTAGE SUPPLY
CONTENTS
TABLE OF CONTENTS
section
GENERAL DESCRIPTION ........
1.
l-1.
1-2.
General ...........
Features ..........
l-3. Applications ........ 1
1-4. Specifications ....... 2
1-5.
Accessories ......... 2
l-6. Equipment Received ..... 2
2.
OPERATION.
2-1.
Front Panel Controls and
Terminals
2-2.
2-3.
2-4.
CIRCUIT DESCRIPTION ........
3.
3-l.
3-2.
Operating Procedures .... 4
Overloads
Floating Operation .....
General ...........
AC Control Circuits ..... 5
............
.........
..........
3-3; Low and High Voltage Supplies 5
3-4.
4.
SERVICING. ............
4-1.
4-2.
Regulator Circuit ......
General ...........
Servicing Schedule .....
Page
1
1
1
3
3
4
4
5
5
6
7
7
7
Section
4-3.
4-4.
4-5.
Parts Replacement . . . . . . 7
Troubleshooting . . . . . . . 7
Procedures to Guide
Page
Troubleshooting , . . . , , 8
4-6.
4-7.
Correcting for No Output , . 9
Correcting for Inaccurate
Voltage Output . . . . . . . 9
4-a.
Bias Adjustment , . . . . . .lO
4-9. Improperly Working Overload .lO
5.
CALIBRATION . . . . . . . . . . . .ll
5-1.
5-2.
5-3.
REPLACEABLE PARTS . . . . . . . . .17
6.
6-l.
6-2.
General . . . . . . . . . . .ll
Calibration Schedule . . . .ll
Output Calibration . . . . .ll
Replaceable Parts List . . .17
How to Order Parts . . . . .17
Model 242 Replaceable Parts
List . . . . . . . . . . .~ .18
Model 242 Schematic Diagram
14661D . . . . , . , . . . .25
'*Change Notice
QkYellow Change Notice sheet is included only
for instrument modifications affecting the
Instruction Manual.
0865R
i
KODEL 242 VOLTAGE SUPPLY
GENERAL DESCRIPTION
SECTION 1.
l-l. GENERAL.
stable outputs between 300 and 3500 volts dc.
milliamperes. Stability is 20.01% for six months after a 30-minute warm-up. Line regula-
tion is within ?O.OOS% for a 10% change in line voltage,
iO.OOS% from zero to full load.
l-2.
trol interpolates between steps with resolution better than 15 millivolts.
selected positive or negative, or floated up to 1000 volts off chassis ground.
zener diode reference, a photo-modulator comparator and wirewound sampling resistors.
ulator and epoxy encapsulated power transformers.
filled, metal-cased construction with mylar dielectric.
l-3. APPLICATIONS. The Model 242 is an excellent source for phototubes, photo-multiplier
tubes and other detectors requiring high voltage biasing with superior stability. Its
current capability permits parallel operation of photo-multiplier divider strings.
applications include use in calibration tests, voltage gradient studies, insulation tests
and leakage resistance measurements.
FEATURES.
Four in-line calibrated dials set the output voltage in l-volt steps.
a.
Cumulative drift is prevented by a chopper circuit with a temperature-compensated
b.
c. The Model 242 uses heavy duty thermionic rectifiers,
The Keithley Model 242 Regulated High Voltage Supply provides accurate,
GENERAL DESCRIPTION
Accuracy is -0.1% for all loads up to 25
and load regulation is within
A TRIM Con-
Output can be
a maintenance-free photo-mod-
All high voltage capacitors are of oil-
Other
FI
:GURE 1. Keithley Instruments Model 242 Regulated High Voltage Supply. The Voltage
Supply is shown with the Model 2421 End Frames, for bench use.
0865R
1
GENERAL DESCRIPTION
MODEL 242 VOLTAGE SUPqLY
l-4.
OUTPUT:
ACCURACY:
RESOLUTION:
ter than 15 millivolts.
RESETABILITY: 20.01%.
STABILITY:
TEMPERATURE COEFFICIENT: &5 ppm/OC maximum.
LINE REGULATION:
LOAD REGULATION:
RIPPLE AND NOISE:
SPECIFICATIONS.
Voltage:
Current:
Polarity:
Floating:
300 to 3500 volts dc in l-volt steps.
25 milliamperes dc maximum.
20.1% of dial setting.
20.01% per 6 months after a 30-minute warm-up.
Positive or negative.
1000 volts maximum off chassis ground.
A,TRIM Control permits interpolation between steps with a resolution of bet-
+0.005% for 10% change in line voltage.
;fO.OOS% from zero to full load.
Less than 2 millivolts rms above. 5 cps.
OVERLOAD PROTECTION:
approximately 27 milliamperes.
CONNECTORS:
POWER: 105-125 volts, SO-60 cps, 250 watts. 210-250 volt models available.
DIMENSIONS, WEIGHT:
pounds.
ACCESSORIES SUPPLIED: Mating connectors.
l-5. ACCESSORIES.
2421 End Frames for bench use.
ing hardware, fastens to the Voltage Supply sides and front panel.
l-6. EQUIPMENT RECEIVED. The Model 242 Voltage Supply is factory calibrated. Two vacuum
tubes, the 7235 (V4, Figure 10) and the 4-658 (V12, Figure 8) are packed separately to
prevent damage during shipping.
cap and the other with a plain protective cap.
struction Manual and two mating output plugs.
Before shipping the Model 242, always remove tubes V8 and Vl2.
separately to prevent damage during shipping.
Output:
Output is disconnected within 25 mFlliseconds if current exceeds
Two Teflon-insulated hn type. Ground:
7 inches high x 19 inches wide x 13-l/4 inches deep; net weight, 39
The Model 242 is designed for rack mounting and requires the Model
The pair of end frames, which comes with feet and mount-
Both output receptacles are capped, one with a red shorting
The shipping carton also contains the In-
NOTE
Binding post.
Pack these
1065R
MGDEL 242 VOLTAGE SUPPLY
OPERATION
SECTION 2.
2-1. FRONT PANEL CONTROLS AND TERMINALS (See Figure 2).
a. Voltage Switches. Four skirted dials, calibrated in 1000, 100, 10 and l-volt steps,
set the output voltage from 300 to 3500 volts dc.
TRIM Control. The TRIM Control extrapolates between l-volt settings with a resolu-
b.
tion to 15 millivolts. The span of the control is 1.5 volts.
c. POWER Switch. A toggle switch energizes the filament and low voltage supplies to
the Model 242. When the Switch is ON, the POWER pilot light will glow green to indicate
the instrument is on. The Fuse for the control circuits is next to the Switch.
d. HIGH VOLTAGE Switch.
also resets the High Voltage Supply after an overload.
the RIGH VOLTAGE Switch is ON. When the Switch is off, the high voltage output is disconnected, although the filament and low voltage circuits continue operating.
the high voltage circuit is next to the Switch.
e. OUTPUT Receptacles. Rro hn-type receptacles (UG 496/U) are on the front panel,
marked for negative (-) and positive (+) outputs with respect to the chassis.
post (GND) is between the receptacles.
receptacle during normal operation.
242 is not operating.
A toggle switch controls the high voltage output circuits and
The red cap is a shorting cap to ground the unused
The other cap protects the receptacle when the Model
OPERATION
The amber pilot light indicates
The Fuse for
The ground
f. OVERLOAD Pilot Light.
the overload relay opens the high voltage output circuit and lights the red
Light. The Pilot Light also lights for settings below 300 volts.
FIGURE 2.
Replaceable Parts List and the schematic diagram.
Model 242 Front Panel Controls and Terminals, Circuit designations refer to
When the output current exceeds approximately 27 milliamperes,
Xlmm "olfaga switch CSS)
Xl00 "okage Stitch (56)
s"itd,
OVER,l,OAD
Pilot
1065R
OPERATION
MODEL 242 VOLTAGE SUPPLY
2-2.
OPERGTING PROCEDURES.
a. Keep the POWER Switch, HIGH VOLTAGE Switch and TRIM Control off. Connect the power
cord at the back of the cabinet to an outlet.
ment ,
to the + OUTPUT Receptacle;
ground the negative line.
the Model 242 connects into 105-125 volt, 50-60 cps sources.
Connect the load to the Model 242. For positive'polarity output, connect the cable
b.
connect the red shorting cap to the - OUTPUT Receptacle to
The + OUTPUT Receptacle has its center terminal at positive
polarity and its shell at chassis ground.
Unless otherwise specified on the instru-
Reverse procedures for negative polarity
output.
Set the POWER Switch to ON.
C.
Select the output voltage by setting the four Voltage
Switches between 300 and 3,500 volts.
NOTE
Make sure the TRIM Control is set to OFF.
If it is on, up to 1.5 volts will be
added to the displayed output.
Warm up the Model 242 for 30 seconds.
d.
Put the HIGH VOLTAGE Switch in ON position.
Warm up the Model 242 for approximately 30 minutes for maximum output stability.
NOTE
The OVERLOAD Pilot Light will light if the HIGH VOLTAGE Switch is ON when
the POWER Switch is turned on. OVERLOAD will also light if the circuits are not
warmed up.
When the OVERLOAD bulb lights, put the HIGH VOLTAGE Switch off and
wait 30 seconds. Then put on HIGH VOLTAGE Switch again.
e. If desired, use the TRIM Control for settings between the l-volt steps.
Resolution
is better than 15 millivolts.
When resetting output voltage or changing terminals, put the HIGH VOLTAGE Switch to
f.
OFF position.
for the output change.
2-3.
OVERLOADS.
The POWER Switch can remain on as long as the HIGH VOLTAGE Switch is off
Only the green light should be on for this step.
If the red OVERLOAD Pilot Light lights, the circuit is overloaded and
the output is disconnected. To reset the Model 242, snap the HIGH VOLTAGE Switch off,
wait 30 seconds, then put it on again.
Refer to Section 4 if the OVERLOAD Pilot Light
continues to light.
2-4. FLOATING OPERATION.
Remove the shorting cap from the receptacle. Connect two
separate shielded coaxial cables, type RG-149/U or equivalent, to the OUTPUT Receptacles,
one for positive and one for negative polarity,
Use only the two furnished connectors
and the specified shielded cables because of the high potentials present.
NOTE
Do not float the Voltage Supply more than 1000 volts off chassis ground.
of the high voltages present,
make sure all instructions are understood and fol-
Because
lowed before attempting floating operations.
4
1065R
MODEL 242 VOLTAGE SUPPLY
CIRCUIT DESCRIPTION
SECTION 3. CIRCUIT DESCRIPTION
3-l.
stable outputs from 300 to 3500 volts dc.
tionship between the operating circuits.
selects the output voltage.
free photo-modulator compares a portion of
the output to the sener diode reference.
The difference is amplified and used to
control the series regulator tube.
maintains the output voltage constant at a
level determined by the divider ratio.selected with the front panel Voltage Switches.
3-2. AC CONTROL CIRCUITS.
ure 4.)
pletes the circuit from the power line to
transformer Tl, which furnishes the bias
voltages, and to filament transformer T3..
If the HIGH VOLTAGE Switch, 54, is off, the
control relay, K2, will close.
to transformer T2, which supplies high voltages to the series regulator, can now operate when the HIGH VOLTAGE Switch is turned
On.
GENERAL.
Refer to Schematic Diagram 14661D
for circuit designations.
Closing the POWER Switch, Sl, com-
a.
The Keithley Model 242 Regulated High Voltage Supply furnishes accurate,
Setting the sampling resistors in the divider
The maintenance-
This
NOTE
(Refer to Fig-
The circuit
The block diagram, Figure 3, shows the rela-
LkID"r
I -
I
,&Qgig+Il
FIGURE 3.
Ll".
mwc
Model 242 Block Diagram.
If the HIGH VOLTAGE Switch is already
b.
ON when the POWER Switch is put ON, the circuit activating the control relay is open.
Therefore, transformer T2 can not function,
even though the other two transformers are
operating. FIGURB 4.
Circuits.
c. The Model 242 has several safety de-
vices in its ac control circuits.
load relay, Kl, breaks the circuit to the
control relay and to transformer T2 if the
output current exceeds approximately 27 milliamperes. The decade interlocks, 55 and 56,
will not close for outputs less than 300 volts.
3-3. LOW AND HIGH VOLTAGE SUPPLIES.
Transformer Tl supplies low voltages to bias the circuits and to furnish the voltage
a.
for the sener diode reference. A separate winding, along with tube V9, provides regulated
105 volts to the screen of the series regulator tube, V12.
1065R
The over-
Circuit designations refer to schematic digram.
Simplified Diagram of AC Contra
All circuits are shown open.
The transformer also provides
5
CIRCUIT DESCRIPTION
MODEL 242 VOLTAGE SUPPLY
the gating voltage for the diode bridge demodulator, D106 to D109.
Transformer T2 supplies the high voltages for the series regulator.
b.
The transformer
primary is tapped to furnish a different voltage for each lOOO-volt range. This prevents
exceeding the voltage and power rating of the series regulator, Vl2, under any of the
specified line and load conditions,
Two rectifiers, tubes VlO and Vll, convert the trans-
former output to full-wave rectified dc for the series regulator, V12.
3-4.
REGULATOR CIRCUIT. (See Figure 5.)
The regulator circuit uses a photo-
a,
modulator to compare the output voltage to
the selected voltage,
Any difference is
amplified and returned to the series regu-
lator to correct the output.
For low-frequency fluctuations at the
b.
output, the voltage divider and the sampling
resistors on the decade switches divide the
output voltage.
The photo-modulator, ElOl,
_
compares the reference voltage across aener
diode D103 and the divided output voltage.
The photo-modulator develops an ac signal
for any dc voltage difference. The signal
is then amplified by tube V2 and demodulated
FIGURE 5.
Circuit.
Simplified Diagram of Regulator
by the diode bridge, D106 to D109. The dc
signal is further amplified by V3 and V4
and applied to the bias of the series regulator tube, ~12.
t
For high-frequency fluctuations and transients in the output, the feedback loop is
c.
through capacitor Cl20 to the grid of tube V4, which applies the signal to the bias of
the series regulator tube, V12.
The voltage switching is done by current sensing, which means no switch contact is
d.
required to
carry
more than 5 milliamperes or switch more than 9 volts.
6
0965R
MODEL 242 VOLTAGE SUPPLY
SERVICING
SECTION 4.
4-1.
Mode1~242 Voltage Supply.
tions of the instrument.
4-2. SERVICING SCHEDULE.
mal care required of high-quality electronic equipment,
described in Section 5, will show the need for any adjustments. No part should need frequent replacement under ordinary use.
4-3.
Voltage Supply.
which meet the specifications.
as a pair.
sentative, as well as other parts marked for Keithley manufacture in the Replaceable Parts
List.
4-4.
GENERAL. Section 4 contains the maintenance and troubleshooting procedures for the
Follow these as closely as possible to maintain the specifica-
The Model 242 requires no periodic maintenance beyond the nor-
PARTS REPLACEMENT.
a. The Replaceable Parts List in Section 6 describes the electrical components of the
Replace components only a8 necessary.
The aener diode, D103, is selected, Diodes D104 and D105 are matched; replace only
b.
Order these replacements only from Keithley Instruments, Inc., or its repre-
TROUBLESHOOTING.
SERVICINO
Occasional checks of the output,
Use only reliable replacements
a. The procedures which follow give instructions for repairing troubles which might
occur in the Model 242,
parts.
located or repaired, contact Keithley Instruments, Inc.,
Keithley Instruments Model 153 MicrovoltAnrmeter, 1% accuracy at 100 millLvolts
Tektronix Type 503 Oscilloscope, 1 mv/cm sen- Adjust bias
sitivity, dc ‘to 450 kc
dc voltmeter, 10% accuracy, to 4000 volts,
lo-megohm minimum input resistance
Grid-modulated tube tester
lo-ohm, l/2 watt, l/2% deposited carbon
resistor (Keithley Part R12-10)
NE-1 neon tube; l/2 watt, l/Z% deposited
carbon resistor; 0.5-microfarad, 400C-volt
capacitor
Table 1 lists equipment recommended for troubleshooting.
Instrument
Use the procedures outlined and uee only specified replacement
If the trouble cannot be
or
its representative.
Use
Zener circuit adjustment
Measure dc voltages
Test vacuum tubes
Zener circuit adjustment
Adjust bias
TABLE 1.
their equivalents.
1065R
Equipment Recommended for Model 242 Troubleshooting. Use these instruments or
7
SERVICING MODEL 242 VOLTAGE SUPPLY
Trouble
Probable Cause
Remedy
J output Blown fuse, Fl or F2 Replace fuse; if fuse again
check further
Defective VlO, Vll, R113
blows,
See paragraph 4-6
or cl06
Defective series regulator
See paragraph 4-6
v12
utput voltage not stable Defective Cl15 Check capacitor; replace if
faulty
utput voltage not accurate
Power Supply out of Recalibrate per paragraph 5-3
calibration
Improper zener adjustment See paragraph 4-7
xcessive noise in output Bias out of adjustment See paragraph 4-8
verload circuits cuts off Defective R118 or Kl
See paragraph 4-9
ith no overload
Defective Cl15 Check capacitor; replace if
faulty
oltage Supply operates Cl16 shorted Check capacitor; replace
ven when overloaded
TABLE 2.
b.
Model 242 Troubleshooting. Read paragraph 4-5 before performing any repairs.
Table 2 lists problems which might occur.
If the repair indicated does not work,
check through each circuit as~described in the following paragraphs.
if faulty
Refer to the circuit description in Section 3 to find the more crucial components and to determine their
function.
The complete
circuit
diagram, 14661D, is in Section 6.
4-5. PROCEDURES TO GUIDE TROUBLESHOOTING.
Before troubleshooting the Voltage Supply, check the external circuits.
a.
fuse, power cord and power source.
ages referenced to chassis ground.
Check the vacuum tubes.
b.
Normally, replacing tubes will clear up any difficulty.
The Schematic Diagram indicates the tube element volt-
Measure the dc voltages to
rlO% of the indicated values.
Check the
All tubes except V4, VlO, Vll and V12 are readily tested on a grid-modulated tube tester.
Check the remaining four tubes by replacing them.
NOTE
Before removing the top or bottom cover,
make sure the power cord is disconnected.
After removing the cover, discharne all metal-cased capacitors before proceeding
with repairs,
Discharge all high voltages through a bleeder.
c. Remove the Model 242 covers.
8
Do not put a load on the instrument. Put the red
0865R
MODEL 242 VOLTAGE SUPPLY SERVICING
shorting cap on the - OUTPUT Receptacle.
make sure the TRIM Control is off. Put on the POWER and HIGH VOLTAGE Switches, as outlined
in paragraph 2-2.
Be careful working inside the chassis. If the POWER Switch is on, up to 200 volts
may appear at points in the control circuits. High voltage appears on both sides
of the chassis. Before working on a faulty Voltage Supply, disconnect the power
cord and discharge all filter capacitors, as Cl06 and C115.
4-6.
pozsible to have a high voltage output
Replace defective fuses. If the fuse again blows, check further for the cause.
measures to 4000 volts.
this measurement.
CORRECTING FOR NO OUTPUT.
Check both front panel fuses. The HIGH VOLTAGE Pilot Light indicates when it is
Measure the plate voltage of series regulator tube V12. Use a dc voltmeter which
b.
Make sure the Voltage Switches are set at 300 volts before making
The plate voltage should be 2000 volts f20%.
Set the Voltage Switches for a 300-volt output;
NOTE
; however, it can light even when the fuse is blown.
NOTE
Discharge high voltage from tube V12 through a bleeder.
directly to the chassis may damage resistor R113 or diode DlOl.
c. If the plate voltage is not correct, check rectifiers VlO and Vll, the series resis-
tor R113 (Figure ll), the filter capacitor Cl06 (Figure 8) and the primary winding of
transformer T2 (Figure 8) for 117 volts.ac. If no voltage appears on the transformer pri-
mary, check the overload relay, Kl (Figure lo), and the control relay, K2 (Figure 8).
If the plate voltage of tube V12 is correct, check the cathode voltage across pin 1
d.
or 7 to ground. The voltage should be 300 volts *LO%.
Incorrect voltage at the cathode indicates tube V12 is faulty or incorrect biasing
e.
conditions exist. If the voltage is still not correct after tube V12 is replaced, check
tube V4 (Figure lo), the dc amplifier tube V3 (Figure lo),
ure lo), and the diodes in the demodulating bridge, D106 to DlC9 (Figure 10).
If the plate voltage of V12 is correct, check the overload relay Kl. Refer to par-
f.
agraph 4-9.
4-7. CORRECTING FOR INACCURATE VOLTAGE OUTPUT. Poor regulation or excessive drift will
affect the accuracy of the voltage output. Several factors cause this; check the following.
a. A defective capacitor Cl15 (Figure 8) will cause the output to be unstable.
Although it normally does not need replacement, check the zener diode D103 (Figure
b.
8).
Since adjusting the diode circuit requires recalibrating the entire instrument, check
the zener diode only after all other possible trouble sources are eliminated.
Discharging the cap
the ac amplifier tube V2 (Fig-
1. Remove the jumper in series with diode D103 (the jumper is next to R133, Figure 9).
SERVICING
1
Connect a lo-ohm, l/2% resistor (Ke-ithley Part No. R12-10) at this point. Read the volt,
age across the resistor with the Model 153.
(Figure 9), until the microvoltmeter reads the product of the rated zener current (7.5
milliamperes) times the resistance (10 ohms) or 75 millivolts *l%.
Adjust the ZENER ADJ potentiometer, R133
MODEL 242 VOLTAGE SUPPLY
The voltage across the zener diode should now be between 8.55 and 9.45 volts.
2.
this voltage is not correct,
(Figure ll), the ZBNER ADJ potentiometer R133 and the zener diode D103.
After adjusting the voltage, recalibrate the Model 242 (paragraph 5-3).
3.
4-8.
shown in Figure 6.
will allow a full load - 25 milliamperes
- on the Model 242.
Voltage Supply to 1000 volts output and use
a 25-kilohm resistor.
4000-volt blocking capacitor in series with
the oscilloscope for protection.
the output on the oscilloscope. The oscil-
loscope should show a signal with Z-millivolt rms ripple or less. Adjust the BIAS
ADJ potentiometer, R144 (Figure 9), until the
minimum ripple appears on the oscilloscope.
ficient range to lessen the noise, check capacitor ClO8.
open, it will cause excessive noise. If it is good,
of corona indicates the feedback capacitor Cl20 (Figure 9) is open or the core of transfor-
mer T2 (Figure 8) is grounded.
BIAS ADJiTSTMENT.
Connect the Model 242 to the circuit
a.
Use a resistor which
For example, set the 0 0
Use a 0.5-microfarad,
Turn the Voltage Supply on; monitor
b.
c. If the potentiometer does not have suf-
check the regulator tube Vl (Figure lo), resistor R132
OscFlloscope
Model 242
- +
FIGURE 6. Circuit Diagram for Model 242
Bias Adjustment. Refer to paragraph 4-8
for procedures and Table 1 for equipment.
If capacitor Cl08 (Figure 10) Fs
observe the output wave. A high level
+ -
If
w
4-9. IMPROPERLY WORKING OVERLOAD.
If the OVElUOAD Lamp keeps lighting when the instrument is turned on, turn it off
a.
and remove the load. If the instrument works when the load is not present, the overload
is in the external circuit.
Model 242 for the trouble.
matic Diagram.
If the overload relay Kl (Figure 10) will not break the circuit when the Voltage
b.
Supply becomes overloaded,
the overload relay for proper operation.
c. If the overload relay cuts off the circuit with no'overload present, check the coil
of Kl (Figure 10) against the rated value printed on it.
tance R118 (Figure 9) to make sure its value has not changed.
If previous checks have not located the source,
d.
leaky or shorted capacitor here will cause troubles similar to those caused by a faulty
overload circuit.
10
If the instrument continues to show an overload, check the
Check the circuit voltages against those marked on the Sche-
check filter capacitor Cl16 (Figure 10) for a short and check
Also check the shunting resis-
check capacitor Cl15 (Figure,8). A
1065R
MODEL 242 VOLTAGE SUPPLY CALIBRATION
SECTION 5.
5-1.
recommended that the equipment listed in Table 3 be used.
contact Keithley Instruments, Inc., or its representative.
troubleshooting procedures or contact Keithley Instruments, Inc., or its representative.
5-2. CALIBRATION SCHEDULE.
Also recalibrate the instrument if the series regulator tube, V12, is replaced. Replacing
or adjusting the zener diode, D103, also necessitates recalibrating the output.
5-3. OUTPUT CALIBRATION.
tial Voltmeter (*0.02% limit of error) and the Model 6601A Divider (ti.Ol% limit of error).
Total limit of error of this system is f0.03%. The Model 660A Differential Voltmeter may
be used directly for output voltages from 300 to 500 volts.
GENERAL.
a. The following procedures are recommended for calibrating the Model 242.
This Section covers calibrating the accuracy of the output voltage.
b.
If the instrument is not within specifications after the calibration, follow the
c.
Check the accuracy of the output voltage every six months.
Set up the Model 242 according to Figure 7.
a.
CALIBRATION
It is also
If difficulty is encountered,
Use the Model 660A Guarded dc Differcn-
Turn on the Model 242.
b.
off before making the calibration. The voltmeter should read 3500 volts r3.5 volts. If
necessary, adjust the HV ADJ potentiometer, R136 (Figure 9), until the output reads 3500
volts on the Model 660A Voltmeter.
Be careful making internal adjustments.
present inside the instrument.
Set the Voltage Switches to 300 volts.
C.
volt.
Teads 300 volts on the Model 660A Voltmeter.
Keithley Instruments Model 660A Guarded dc
Differential Voltmeter, 20.02% limit of
error, 100 millivolts to 500 volts
Keithley Instruments Model 6601A Voltage
Divider, lOO:l, 100 volts to 5000 volts,
-To. 01% accuracy
If necessary, adjust the LV ADJ potentiometer, R142 (Figure 9), until the output
Instrument
Set the output to 3500 volts; make surs the TRIM Control is
CAUTION
Up to 5000 volts dc and 3600 volts ac are
The voltmeter should read 300 volts $0.3
Use
Calibrate accuracy of output
Calibrate accuracy of output
TABLE 3. Equipment Recommended for Model 242 Calibration.
equivalents.
Use these instruments or their
11
CALIBRATION
Repeat the 3500 and 300-volt adjustments until there is no discrepency between the
d.
Model 242 output setting and the Model 660A Voltmeter reading.
MODEL 242 VOLTAGE SUPPLY
FI
LE 7.
equipment.
Control
Zener Adjustment
High Voltage Adjustment
Low Voltage Adiustment
Bias Adjustment
I
TABLE 4. Model 242 Internal Controls.
picturing the'location and the paragraph describing the adjustment.
Block Diagram for Calibrating Model 242 Output Accuracy.
Use coaxial cable to connect the Models 242 and 6601A.
I
Circuit
Desig.
R133
R136
R142 9 5-3
Rl44
The Table lists all internal controls, the figure
Fig.
Ref.
9
9
See Table 3 for
Refer to
Paragraph
4-7
5-3
12
1065R
MODEL 242 VOLTAGE SUPPLY
CALIBRATION
(W
R21!
SH Figs. 10, 11
(R20
Rm
.“” ,,
FIGURE 8.
Top View of Model 242 Chassis. The illustration shows the location of com-
ponents and printed circuit. Refer to Figure 9 for a bottom view.
0865R
13
CALIBRATION MODEL 242 VOLTAGE SUPPLY
FIGURE 9. Bottom View of Model 242 Chassis.
ponents and internal controls.
Refer to Figure 8 for a top view.
14
, ::z
The illustration shows the location of corn
086 '5R
MODEL 242 VOLTAGE SUPPLY
CALIBRATION
FIGURE 10.
Resistors are shown in Figure 11.
0865R
Tube, Diode, Capacitor and Modulator Locations on Printed Circuit Board PC-100.
15
CALIBRATION MODEL 242 VOLTAGE SUPPLY
FIGURE 11.
shown in Figure 10.
16
Resistor Locations on Printed Circuit Board PC-100. Other components are
0865R
MODEL 242 VOLTAGE SUPPLY REPLACEABLE PARTS
SECTION 6.
6-l. REPLACEABLE PARTS LIST.
Model 242 Regulated High Voltage Supply. The List gives the circuit designation, the
part description,
Part Number.
dress of the manufacturers listed in the "Mfg. Code"
6-2.
Part Number, the circuit designation and a description of the part. All structural parts
and those parts coded for Keithley manufacture (80164) must be ordered from Keithley
Instruments, Inc. , or its representative.
Parts List, completely des&ibe the part,
ment, Keithley Instruments, Inc.
=mP
CbVar
CerD
camp
CompV
DCb
ETB
ETT
HOW TO ORDER PARTS.
For parts orders, include the instrument's model and serial number, the Keithley
a.
Order parts through your nearest Keithley representative or the Sales Service Depart-
b.
ampere
Carbon Variable
Ceramic, Disc
composition
Composition Variable
Deposited Carbon
Electrolytic, tubular
Electrolytic, tantalum
a suggested manufacturer, the manufacturer's part number and the Keithley
The last column indicates the figure picturing the part.
The Replaceable Parts List describes the components of the
REPLACEABLE PARTS
The name and ad-
column are contained in Table 6.
In ordering a part not listed in the Replaceable
its function and its location.
M or meg
kg.
Mil. No.
MY
n
P
i-I ’
mega (106) or megohms
milli (10-3)
Manufacturer
Military Type Number
Mylar
pica (lo-121
micro (10-6)
k
f
farad
kilo (103)
v
Var
zw
WWVar
TABLE 5. Abbreviations and Symbols.
volt
Variable
watt
Wirewound
Wirewound Variable
17
REPLACEABLE PARTS
(Refer to Schematic Diagram 14661DBfor circuit designations.)
MODEL 242 VOLTAGE SUPPLY
MODEL 242 REPLACFA LE PARTS LIST
CAPACITORS
Circuit Mfg.
Desin.
Cl01
Cl02
Cl03
Value
0.1 Kf
10 I*f
.Ol )Jf
Cl04 20 wf
Cl05
Cl06
Cl07
Cl08
Cl09
20 iJ.f
.5 IJf
47 Pf.
100 pf
1.0 Ff
Rating
200 v
450 v
500 v
600 v
350 v
6000 v
500 "
25 v
200 v
TYPO
MY 02777
ETB 37942
CerD 72982
ETB 14655
ETB 56289
MY 99120
CerD 72982,
ETB 56289
MY 13050
Code
Cl10 Not Used
Cl11
Cl12
Cl13
Cl14
2
uf
2
IJf
.OOl Kf
0.1 wf
Cl15 *OS-.5 IJ.f
Cl16
Cl17
Cl18
Cl19
Cl20
.02 pf
.0022 IJ.f
.Ol Kf
.Ol pf
,005 pf
50 v
50 v
500 v
200 v
5000 v
500 v
1000 "
500 v
500 v
3000 v
ETT 37942 TC302 C39-2M
ETT 37942 TC302 C39-2M 10
CerD 72982 801-OOO-Z5U-OOl-102M c22-.oolM 10
MY 02777
MY 99120 LK50-555A C51-.05/.5M 8
CerD 72982
CerD 56289
CerD 72982
CerD 72982
CerD 71590
Mfg. Keithley
Fig.
Part No. Part No. Ref.
P-12M
TC-72
811-000-25UO-103M
BR20-600
TVA1608
LK60-504
831-OOO-Z5F-470M
TVA1207
107-21
C66-.lM
C8-10M
C22-.OlM
C35-20M
C23-20M
C74-.5M
C22-47P
ClO-100M
C66-l.OM
10
10
10
10
10
8
9
10
10
LO
P-12M
841-000-25UO-203M
5GAD22
all-000-25UO-103M
811-000-Z5UO-103M
DD30-502
C66-.lM
C22-.02M
C72-.0022M
C22-.OlM
C22-.OlM
C75-.005M
10
10
10
10
10
9
Cl21 .l uf
200 v
MY 02777
DIODES
Circuit
Desig.
TYPO
DlOl Silicon
Number
lN3255
D102 Not Used
D103
D104 Silicon
D105 Silicon
D106 Silicon
D107 Silicon
D108
D109 Silicon
DllO Silicon
Zener
Silicon
lN938
lN3253
lN3253
lN3253 02735 RF-20 10
lN3253 02735 RF-20 10
lN3253
lN3253
lN3253
ye D104 and D105 are matched; replace as a pair.
18
P-12M
Mfg.
Code
02735
80164
80164
80164
02735
C66-.lM 10
Keithley
Part No. Ref.
RF-17 10
DZ-6 8
*17459A 10
*17459A 10
RF-20
02735 RF-20 10
02735 RF-20
Fig.
10
10
1065R
MODEL 242 VOLTAGE SUPPLY
REPLACEABLE PARTS
MISCELLANEOUS PARTS
circuit
Desig.
DSl
DS2
DS3
-
El01
Fl (117 v)
FL (234 v)
F2 (117 v)
F2 (234 v)
-
Jl
Mfg.
Description
Code
Pilot Light Assembly, Green, POWER (Mfg.
No. 5201-232) 72619
Pilot Light Assembly, Red, OVERLOAD (Mfg.
No. 5201-211) 72619
Pilot Light Assembly, Amber, HIGH VOLTAGE
(Mfg. No. 5201-213) 72619
Lamp, 3 req'd (Mfg. No. 47) 08804 PL-4
Photo Modulator 80164
Fuse, slow blow, 1.5 amp (Mfg. Type MDX)
Fuse,
slow blow, .75 amp, 3 AG (Mfg. No.
313.7501
71400
75915
Fuse, slbw blow, 2 amp, 3 AG (Mfg. No.
313002'1
Fuse, siow blow, 1 amp (Mfg. Type MDL)
Fuse holder, two req'd (Mfg. No. 342012)
75915 FU- 25
71400
75915
Receptacle, hn, OUTPUT + 80164
Keithley
Pal-t No. Ref.
PL- 56
PL5RF
PL-5AF
1512
FU-16
FU- 14
FU- 10
FH- 3
cs-79
52 Receptacle, hn, OUTPUT - 80164 cs-79
Fig.
10
2
2
2
2
2
2
-
(F) Plug, hn, Mate of Jl and 52, Mil. No.
IJG-59A/U (Mfg. No. 82-38)
-
-
Binding Post, GND (Mfg. No. 938-A)
Cap and Chain Assembly, non-shorting (Mfg.
No. 5207)
-
Cap and Chain Assembly, red short& (Mfg.
No. 5816)
Kl Relay, Overload
K2 Relay, DPDT
Pl Cord Set, 6 feet (Mfg. No. 4638-13)
-
Tl
ill7 v) Transformer, Power
Tl
,234 v)
Cable Clamp (Mfg. No. SR-5P-1)
Transformer, Power
T2 :117 v) Transformer, High Voltage
1234 v)
T2
Transformer, High Voltage
T3 ,117 v) Transformer, Filament
T3 :234 v) Transformer, Filament
(F) Furnished accessories.
02660 CS-80
24655 BP- 1 2
91737 CAP-15 2
91737 CAP-8
80164
RL- 21
10
80164 RL-16 8
93656 co-5
28520 cc-4
80164 TR-47
80164 TR-73
80164 TR-48
80164 TR-74
80164 TR-46
80164 TR-72
8
8
8
8
8
8
2
1365R
19
REPLACEABLE PARTS
MODEL 242 VOLTAGE SUPPLY
RESISTORS
Circuit
Desig.
RlOl
R102
R103
Rl04
Rl05
R106
R107
R108
R109
RllO
Rlll
R112
Rl13
R114
R115
Rll6
R117
Rl18
R119
R120
Value
33 kfi
33 bl
500 n
10 M-l
220 kn
10 m
1m
600 kn
2.2 kn
10 kn
5.6 iTi
100 n
lkl
100 n
100 R
100 n
56
ksl
,'r235 n
100 n
220 m
Rating
lO%, 11.2 w
lO%, l/2 w
l%, 5 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
l%, l/2 w
l%, l/2 w
lO%, 2 w
l%, 5 w
lO%, l/2 w
lO%, l/2 w
l%, 5 w
lO%, l/2 w
lO%, l/2 "
lO%, l/2 w
lO%, l/2 w
l%, l/2 w
lO%, l/2 w
lO%, l/2 w
Type
Comp
Comp
ww
Comp
Comp
Comp
DCb
DCb
Comp
ww
Comp
Comp
WV
Comp
Comp
Comp
Comp
DCb
Comp
Comp
Mfg.
Code
01121
01121
Mfg.
Part No. Part No.
EB
EB
63743 5x
01121
01121
01121
EB
EB
EB
79727 CFE-15
79727 CFE-15
01121
HB
44655 4654
01121
01121
91637
EB
EB
RS-5
01121 EB
01121
01121
01121
79727
01121
01121
EB
EB
EB
CFE-15
EB
EB
Keithley
Rl-33K
Rl-33K
R4A-500
Rl-1OM
Rl-220K
Rl-1OM
Rl2-ZM
R12-600K
R3-2.2K
R4A-10K
Rl-5.6M
Rl-100
R4A-1K
Rl-100
RI-100
Rl-100
Rl-56K
R12-235
Rl-100
Rl-220K
Fig.
Ref.
11
11
11
11
11
11
11
11
11
11
9
9
11
9
9
9
9
9
11
11
R121
Rl22
Rl23
R124
R125
R126
R127
R128
R129
R130
R131
R132
R133
220 kn
10 m
10 ico,
ll%l
330 ks2
22 kn
1l.C
3.3 kn
330 kn
150 kn
5 kn
10 ks2
5 kn
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
10%; l/2 w
lO%, l/2 w
lO%, l/2 w
LO%, l/2 w
lO%, l/2 w
l%, l/2 w
l%, 5 w
l%, 5 w
lO%, 3 w
Rl34 220 kn lO%, l/2 w
R135 a-h
R136
R137
R138
R139
R140
121.875 kn l%, 10 w
50 kn lO%, 2 w
220 kQ
7.5 m
lO%, l/2 w
l%, l/2 w
500 n lO%, 2 w
6m
l%, 1 w
* Nominal value, factory set.
Comp
Comp
Comp
Comp
camp
Comp
Comp
Comp
Comp
DCb
01121
01121 EB
01121
01121
01121
01121
01121
01121
01121
79727
ww 63743
ww 44655
WWVar 37942
Comp
ww
01121
01686
WWVar 75042
Comp 01121
DCb 79727
Comp
DCb
01121
91637
EB
EB
EB
EB
EB
EB
EB
EB
CFE-15
$54
R5000L
EB
TC-10
WP
EB
CFE-15
HB
DC-1
Rl-220K
Rl-1OM
Rl-1OK
Rl-1M
Rl-330K
Rl-22K
Rl-1M
Rl-3.3K
Rl-330K
Rl2-150K
R4A-5K
R4A-10K
RP3-5K
Rl-220K
11
11
11
11
11
11
11
11
11
11
11
11
9
11
Rl21-121.875K 11
RP9A-50K
Rl-220K
Rl2-7.5M
R3-500
R13-6M
9
11
11
11
11
20
0865R
MODEL 242 VOLTAGE SUPPLY
REPMCEABLE PARTS
RESISTORS (Cont'd)
Circuit
Desig. Value
R141
R142
R143
R144
R145
50 kn lO%, 2 w
1i-a
5 kQ
20 kl
100 kn
Mfg.
Rating
20%, l/2 w
'Ww
WVar
CbVar 75042
Code
12697
l%, l/2 w DCb 79727
20%, .2 w
CompV
71450 70 RP7-20K
Mfg.
Part No.
43-50K
RQll-137
CFE-15
l%, l/2 w DC6 79727 CFE-15 Rl2-100K
Keithley
Part No.
RP32-50K
RP2A-1M
R12-5K
R146 100 kn l%, l/2 w DCb 79727 CFE-15 R12-100K
R201
R202
R203
R204
R205
R206
R207
R208
R209
R210
R211
R212
R213
R214
R215
9m
9 kn
9ko
90 kn
45 Ml
22.5 kn
22.5 IQ
900 lul
450 kn
225 kn
:l%, l%, .15 .15 w w
h%, l%, .15 .15 w w
.l%, .15 w
:l%, l%, .15 . 15 w w
:25%, 2 5 % , .15 . 15 w w
.25%, .15 w
w 15909
w 15909
w 15909 1250 Rll-9K
w 15909 1250 Rll-90K
w
15909
w 15909 1250 Rll-22.5K
w
15909 1250 Rll-22.5K
w 01686 7010 RLO-900K
w 01686 7010 RlO-450K
w
01686 7010 RlO-225K
225 kn .25%, .15 w W 01686 7010 RlO-225K 8
9m
4.5 M
2.25 M
2.25 MCI l%, 1 "
l%, 1 w DCb 91‘637 DC-1 R13-9M 8
l%, 1 w DCb 91637 DC-l RL3-4.5M
1%, 1" DCb 91637 DC-l Rl3-2.25M
DCb 91637 DC-L RL3-2.25M 8
1250 Rll-9K
1250
Rll-9K
1250 Rll-45K
Fig.
Ref.
2
9
11
9
11
11
8
8
8
8
8
8
8
8
a
8
a
8
SWITCHES
Circuit
Desig.
Sl
Toggle Switch, SPST, POWER (Mfg. No.
Description
20994LH)
52
53
s4
Not Used
Not Used
Toggle Switch, DPDT, HIGH VOLTAGE
(Mfg. No.
20905-FR) 04009 SW-14
s5 Rotary Switch less components, Xl000
OUTPDT. VOLTS 80164
Rotary Switch with components, Xl000
Output Volts
-
S6
Skirted Knob, Xl000 Switch
Rotary Switch less components, Xl00
OUTPUT VOLTS
-
Rotary Switch with components, Xl00
Output Volts
-
Skirted Knob, Xl00 Switch
Mfg.
Keithley
Fig.
Code Part No. Ref.
04009 SW-4
2
2
SW-190
2
80164 14672~
80164 14634A
80164 SW-131
2
80164 14669B
80164
139238
1065R
21
REPLACEABLE PARTS MODEL 242 VOLTAGE SUPPLY
SWITCHES (Cont'd)
Circuit
Desig.
57
---
---
58
---
---
---
Circuit
Desig.
VL
v2
v3
v4
v5
Description
Rotary Switch less components, X10
OUTPUT VOLTS
Rotary Switch with components, X10
Output Volts
Skirted Knob, Xl0 Switch
Rotary Switch less components, Xl
OUTPUT VOLTS
Rotary Switch with components, Xl
Output Volts
Skirted Knob, Xl Switch
Skirted Knob, Trim Potentiometer
VACUUM TUBES
Number
OB2 86684 EV-OB2 10
12AX7 80164 BV-12AX7
12AX7 80164 EV-12AX7
7235 86684
OG3 73445 EV-OG3
Mfg.
Code
Mfg.
Code Part No, Ref.
80164 SW-132 2
80164 14671B
80164 13923A
80164 SW-132 2
80164 14680B
80164
80164 KN-11
Keithley Fig.
Part No.
EV-7235
Keithley
1392311
Fig.
Ref.
10
10
10
10
~6 12AX7 80164 EV-12AX7
v7
V8
v9
VlO 3B24W
Vll
v12 4-65A
1121 Allen-Bradley Corp. 02777 Hopkins Engineering Co.
Milwaukee, Wis.
1686 RCL Electronics, Inc.
Riverside, N. J. Hartford, Corm.
2660 Amphenol-Borg Electronics Corp.
Broadview, Chicago, Illinois
2735 Radio Corp. of America
Connnercial Receiving Tube and
Semiconductor Division
Somervi.Lle, N. J.
TABLE 6 (Sheet 1).
for Manufacturers, Cataloging Handbook H4-1.)
12B4A 85599 N-12B4A 10
6X4 81453 EV-6X4
OB2 86684 N-OB2
86684
3B24W 86684 N-3B24W
06980
San Fernando, Calif.
04009 Arrow-Hart and Hegeman Electric Co,
04713 Motorola, Inc.
Semiconductor Products Division
Phoenix, Arizona
06980 Eitel-McCullough, Inc.
San Carlos, Calif.
Code List of Suggested Manufacturers. (Based on Federal Supply Code
EV-3B24W
N4-65A
10
10
10
10
10
8
22
L065R
MODEL 242 VOLTAGE SUPPLY
REPLACEABLE PARTS
18804 Lamp Metals and Components
Department G. E. Co.
Cleveland, Ohio
,2697 Clarostat Mfg. Co., Inc.
Dover, N. H.
3050 Potter Co.
Wesson, Miss.
4655 Cornell,-Dubilier Electric Corp.
Newark, N. J.
5909 Daven Division Thomas A. Edison
Industries McGraw Edison Co.,
Livingston, N. J.
4655 General Radio Co.
West Concord, Mass.
8520 Heyman Mfg. Co.
Kenilworth, N. J.
7942 Mallory, P. ,R., and Co., Inc.
Indianapolis, Ind.
.4655 Ohmite Mfg. Co.
Skokie, Ill.
6289 Sprague Electric Co.
North Adams, Mass.
'3743 Ward Leonard Electric Co.
Mount Vernon, N. Y.
72982 Erie Technological Products, Inc.
Erie, Pa.
73445 Amperex Electronic Co. Division of
North American Philips Co., Inc.
Hicksville, N. Y.
75042 International Resistance Co.
Philadelphia, Pa.
75915 Littelfuse, Inc.
Des Plaines, Ill.
79727 Continental-Wirt Electronics Corp.
Philadelphia, Pa.
80164 Keithley Instruments, Inc.
Cleveland, Ohio
81453 Raytheon Co.
Industrial Components Div.
Industrial Tube Operation
Newton, Mass.
83125 General Instrument Corp.
Capacitor Division
Darlington, S. C.
85599 Tube Department G. E. Co.
Schenectady, N. Y.
86684 Radio Corp. of America
Electronic Components and Devices
Harrison, N. J.
1400 Bussmann Mfg. Div. of
McGraw-Edison Co.
St. Louis, MO.
1450 CTS Corp.
Elkhart, Ind.
1590 Centralab Division of
Globe-Union, Inc.
Milwaukee, Wis.
2619 Dialight Corp.
Brooklyn, N. Y.
TABLE 6 (Sheet 2). Code List of Suggested Manufacturers.
for Manufacturers, Cataloging Handbook H4-1.)
1065R
91637 Dale Electronics, Inc.
91737 Gremar Mfg. Co., Inc.
91929 Minneapolis-Honeywell Regulator Co
93656 Electric Cord Co.
99120 Plastic Capacitors, Inc.
Columbus, Nebr.
Wakefield, Mass.
Micro Switch Division
Freeport, 111.
Caldwell, N. J.
Chfcago, Ill.
(Based on Federal Supply Code
23
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