ORTEC 109A Service manual

Printed in U.S.A.
Model 109A
Preamplifier
Operating and Service Manual
This manual applies to instruments
"Rev 14" on rear panel
2606 QIC 0476

Ill
TABLE OF CONTENTS
Page
WARRANTY iv
NOTICE V
PHOTOGRAPH vi
1. DESCRIPTION 1
2. SPECIFICATIONS 1
3. INSTALLATION INSTRUCTIONS 2
3.1 Connection to Detector 2
3.2 Connection to a Shaping Main Amplifier 2
3.3 Input Power 2
3.4 Test Pulse 2
4. OPERATING INSTRUCTIONS 2
4.1 Detector Bias 2
4.2 Linear Output 3
5. CIRCUIT DESCRIPTION 4
5.1 Charge-Sensitive Loop 4
5.2 Voltage Amplifier 4
5.3 Cable Driver 4
6. MAINTENANCE INSTRUCTIONS 4
6.1 Testing Performance 4
6.2 Suggestions for Troubleshooting 5
APPENDIX 7
Replaceable Parts
Block Diagram and Schematic
109A-0101-B1
109A-0101-S1
LIST OF FIGURES
Fig. 1. Bias Resistor Value (Megohms) 3
Fig. 2. Rise Time as a Function of Input Capacitance 3

STANDARD WARRANTY FOR ORTEC INSTRUMENTS
ORTEC warrants that the items will be delivered free from defects in material or workmanship. ORTEC makes no other
warranties, express or implied, and specifical ly NO WARRANTY OF MERCHANTABILITY OR FITNESS FOR A
PARTICULAR PURPOSE.
ORTEC's exclusive liability is limited to repairing or replacing at ORTEC's option, items found by ORTEC to be defective in
workmanship or materials within one year from the date of delivery. ORTEC's liability on any claim of any kind, including
negligence, loss or damages arising out of, connected with, or from the performance or breach thereof, or from the
manufacture, sale, delivery, resale, repair, or use of any item or services covered by this agreement or purchase order, shall in
no case exceed the price allocable to the item or service furnished or any part thereof that gives rise to the claim. In the event
ORTEC fails to manufacture or deliver items called for in this agreement or purchase order, ORTEC's exclusive liability and
buyer's exclusive remedy shall be release of the buyer from the obligation to pay the purchase price. In no event shall ORTEC
be liable for special or consequential damages.
QUALITY CONTROL
Before being approved for shipment, each ORTEC instrument must pass a stringent set of quality control tests designed to
expose any flaws in materials or workmanship. Permanent records of these tests are maintained for use in warranty repair and
as a source of statistical information for design improvements.
REPAIR SERVICE
If it becomes necessary to return this instrument for repair, it is essential that Customer Services be contacted in advance of
its return so that a Return Authorization Number can be assigned to the unit. Also, ORTEC must be informed, either in
writing or by telephone [[phone]] , of the nature of the fault of the instrument being returned and of the model,
serial, and revision ("Rev" on rear panel) numbers. Failure to do so may cause unnecessary delays in getting the unit repaired.
The ORTEC standard procedure requires that instruments returned for repair pass the same quality control tests that are used
for new-production instruments. Instruments that are returned should be packed so that they will withstand normal transit
handling and must be shipped PREPAID via Air Parcel Post or United Parcel Service to the nearest ORTEC repair center. The
address label and the package should include the Return Authorization Number assigned. Instruments being returned that are
damaged in transit due to inadequate packing will be repaired at the sender's expense, and it will be the sender's responsibility
to make claim with the shipper. Instruments not in warranty will be repaired at the standard charge unless they have been
grossly misused or mishandled, in which case the user will be notified prior to the repair being done. A quotation will be sent
with the notification.
DAMAGE IN TRANSIT
Shipments should be examined immediately upon receipt for evidence of external or concealed damage. The carrier making
delivery should be notified immediately of any such damage, since the carrier is normally liable for damage in shipment.
Packing materials, waybil ls, and other such documentation should be preserved in order to establish claims. After such
notification to the carrier, please notify ORTEC of the circumstances so that assistance can be provided in making damage
claims and in providing replacement equipment if necessary.

NOTICE
This preampl ifier has been shipped to you with its pro
tection circuit connected into the circuit ("in"). The
protection circuit makes it almost impossible to destroy the
input FET under normal operating conditions and imposes
an almost negligible resolution degradation. The preamplifier
is thus immune to almost anything the operator is likely
to do in the way of causing transients either at the Detector
Input connector or at the Bias Input connector.
The protection circuit does not protect the detector, but
even if the detector breaks down as a result of overvoltage,
the preamplifier will survive the resulting large transients if
the protection circuit is "in". This, of course, is not true
if the protection circuit is "out", in which case the input
FET is very susceptible to destruction by transients at the
detector input connector.
109A TYPICAL RESOLUTION (keV FWHM)
Ext.
Cap.
(pF)
Protection "out"
(keV)
Protection "in"
(keV)
Rise Time, 10-90% (ns)
Protection "in"
Protection "out"
SI
Ge
Si
Ge
0
50
1000
2.85
3.72
30.4
2.29
2.99
24.4
2.86
4.00
39.5
2.3
3.22
31.7
15
25
250
15
25
250
Slope
0.0276
keV/pF
0.022
keV/pF
0.037
keV/pF
0.0294
keV/pF
If this slight degradation cannot be tolerated, then the
protection circuit can be removed by simply moving the
plug-in jumper from jn to out. The jumper is located on
the printed board next to Q1.
Warranty is voided without the protection circuitry unless
the fol lowing precautions are taken.
1. The detector bias circuitry must be COMPLETELY DIS
CHARGED before a detector, cable, capacitor, or other
capacitive device or low impedance is connected to the
DET. INPUT connector,shown in the Front View on page
V of this manual. (Refer to explanation below.)
2. Discharge the detector bias circuitry before making
ANY connections to the DET. INPUT connector.
To discharge the detector bias circuitry requires that a low
impedance (short circuit preferably) be connected across
the DET. BIAS connector, shown in the Rear View on page
V, for at least 20 SECONDS.
The input transistor will be destroyed if the DET. INPUT
connector is shorted, i.e., by connecting a detector, cable,
capacitor, or other capacitive device such as a voltmeter
probe, etc., while the detector bias components are charged.
A short circuit, short-term or continuous, wil l cause the
applied bias voltage (stored on C3) to be coupled via 03
directly to the input transistor, causing catastrophic break
down. If this happens, the only recourse is to replace Q1
and perhaps Q2 also, depending on the failure mode of Q1.
If a variable bias supply is used, merely turning down the
voltage control to zero and leaving it for at least 20
SECONDS will suffice, since the bias circuitry can discharge
itself through the output impedance of the bias supply.
Sometimes it is necessary to simply disconnect the bias
supply, such as when using batteries for bias. This situation
leaves no discharge path, so a path must be provided by
placing a short circuit or low impedance across the DET.
BIAS connector on the rear panel of the unit.
DO NOT SHORT the DET. INPUT on the front panel.

VI
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1
ORTEC 109A PREAMPLIFIER
1. DESCRIPTION (See Block Diagram)
The 109A is an all-transistor preampl ifier with pole-zero
cancel lation using a field-effect transistor in the input stage.
The circuitry includes a charge-sensitive input loop, an
amplifier stage with switch-selectable gain with a 10:1 ratio,
and a cable driver stage. The preampl ifier is inherently an
inverting preampl ifier: i.e., a negative input pulse yields a
positive output pulse. No pulse shaping is accompl ished
in the preampl ifier, except for a pole-zero-cancelled 50-/xs
differentiation time constant immediately after the charge-
sensitive loop, for the purpose of reduction of pulse pileup
at high count rate. System pulse shaping for optimization
of signal-to-noise ratio wil l be accompl ished in the subse
quent main ampl ifier.
2. SPECIFICATIONS
Basis of Warranty <0.025 keV/pF FWHM (Ge) slope, 2.5 keV FWFIM (Ge) maximum at 0 pF input capacity. Typical perfor
mance is given below:
TYPICAL PERFORMANCE
Noise with 2-ns Preamplifier Output
Single RC Main Amplifier
Pulse
Input
Capacitance
FWHM Si FWHM Ge No. of rms Relative Rise Time (ns).
(pF)
(keV) (keV)
Electrons Amplitude 10-90%
0
2.85 2.29 336
1.000
15
20 3.2 2.6
377 1.000
19
50
3.72 2.99
440 1.000
25
100 5.1
4.1 601
0.996
40
200 7.9
6.4
931
0.993
68
500 16.2
13.0
1910 0.982 175
1000
30.4
24.4 3580
0.963
250
Output Pulse Shape Rise time as in table above, exponential
fal l with bO-fis time constant
Integral Nonlinearlty <0.1% for 0-5 V output span with
internal series termination
Temperature Coefficient ±0.01 %/°C
Detector Bias Isolation 1000 V dc
Input Open Loop Gain >20,000
Power Required +24 V dc at 36 mA, -24 V dc at 36 mA;
supplied from ORTEC main amplifier or from an ORTEC
114 or 115 Preamplifier Power Supply.
Power Cable 10-ft captive power cable is furnished with
each 109A.
COUNT RATE VS. ENERGY See data below, from which it
shaping amplifier.
Input Energy (MeV)
(Si Equivalent)
0.1
1
10
Power Connector Amphenol 17-20090
Saturated Output Amplitude 7 V at end of several hundred
feet of unterminated 93S7 cable
Output Source Impedance Adjustable from 50 to 150J2
Charge Sensitivity 150 mV/MeV (Si), 183 mV/MeV (Ge)
in X10 gain position; 15 mV/MeV (Si), 18.3 mV/MeV (Ge)
in XI gain position
DETECTOR, OUTPUT, AND TEST Pulse Connectors BNC
DETECTOR BIAS Connector SHV
Size 1.8 X 4 X 6 inches (4.5 x 10.2 x 15.3 cm)
Weight Net, 1.5 lb (0.7 kg); gross 2.3 lb (1.1 kg)
is obvious that in almost all cases, the count rate is l imited by the
Count Rate with 1%
Counting Losses (cts/sec)
2x10'
2 X 10'
2x10'

3. INSTALLATION INSTRUCTIONS
3.1 Connection to Detector
A direct connection with shielded coaxial cable should be
made between the detector and the BNC connector labeled
DETECTOR on the front panel.
The performance of the 109A Preampl ifier, like that of all
other such low-noise nuclear amplifier, is degraded as the
capacity at the input of the amplifier increases; for this
reason, it is important that the length of coaxial cable used
between the amplifier and the detector be kept at the
minimum necessary. Also, it is preferable to use 93- or
100J2 impedance cable rather than 75- or 5012 cable, since
the capacity per foot is less for the higher impedance
cable. Type RG-62/U cable, which has 9312 impedance
and a 13.5-pF/ft capacity, is recommended. Type UG-
260/U connectors fit both this cable and the BNC input
connector. Microdot cables and fittings of the series
stocked and suppl ied by ORTEC are also suitable. The
cable is of 10012 impedance, 13 pF/ft. An adapter, ORTEC
No. C-17, may be used on the input BNC connector to
permit use of the Microdot cables. See ORTEC 1970
Nuclear Price List for a complete l isting of compatible
Microdot cables, connectors, and adapters.
Once the input cable has been installed, the electronic noise
performance of the preamplifier can be predicted by
calculating the cable capacity from the above information,
adding the capacity expected from the detector, and
referring to the table of typical performance versus input
capacity (Section 2).
3.2 Connection to a Shaping Main Amplifier
The preampl ifier can be used to drive long 9312 l ine to a
shaping main ampl ifier and is designed to be directly com
patible with the ORTEC transistor main ampl ifiers. It can
be used with any shaping main amplifier if a power supply
is used to power the preamplifier.
3.3 Input Power
Power for the 109A is supplied through the Amphenol
connector (17-20090) on the rear of the chassis. Power may
be supplied by a single 45-V battery with a tap at 22.5 V
(the tap is used as ground, providing -t22.5 V and -22.5 V;
current drain is 36 mA), or any well-filtered power supply
such as the ORTEC 115 Preampl ifier Power Supply that
furnishes both +24 V and -24 V.
If the preampl ifier is used with ORTEC transistor main
ampl ifiers, its power will automatically be supplied from
the main ampl ifier via the interconnecting cable suppl ied
with the 109A.
3.4 Test Pulse
A voltage test pulse can be inserted at the TEST PULSE
connector on the rear of the 109A without the use of an
external charge terminator, since the preamplifier has a
built-in charge terminator. The shape of this voltage pulse
must have a fast rise (less than 10"® sec) followed by a slow
exponential decay back to the basel ine (2 to4 x 10"^ sec).
The input ampl itude can be set to any desired level with
the knowledge that 46 mV amplitude at the TEST PULSE
connector is equal to approximately 1 MeV energy loss in a
silicon detector.
Also, the test pulse can be inserted into the DET. INPUT
connector simultaneously with an operating detector by
using an external charge terminator, provided the charge
terminator will withstand the detector bias voltage.
NOTE; In most experimental situations the optimum
signal-to-noise ratio occurs with the preampl ifier gain
switch in the XI0 position. When this switch is in the XI
position, the signal-to-noise ratio at the preamplifier output
is the same as that of the XI0 position, but the signal level
is only 1/10. At this low signal level, main amplifier noise
contribution becomes more significant. The signal-to-noise
ratio at the output of the main amplifier can be degraded
by the amount of the main ampl ifier noise contribution,and
resolution somtimes suffers.
4. OPERATING INSTRUCTIONS
4.1 Detector Bias
Detector bias is appl ied to the Preampl ifier through the
high-voltage SHV connector.
NOTE: The detector bias components and connectors are
rated and tested at 1000 V. Inside the 109A the detector
bias is appl ied to the DET. INPUT connector through a
decoupling network consisting of R1 (1M12), R2 (100M12)
and C1 (1500 pF) so that the total resistance in series with
the detector bias is approximately 100M12. This resistance
must be taken into account when considering the bias
voltage actually appl ied to a leaky detector. The voltage
dropped in this network wil l be 100 V for each microampere
of detector leakage current. It will be necessary to increase
the bias supply output voltage to compensate for this drop.
Example: It is desired to operate a detector at 100 V bias.
Detector leakage at 100 V = 0.5 fxA. The drop
in the bias network = (100 x 10®) (0.5 x 10'®) =
50 V. Voltage required at bias supply =
100 -I- 50 = 150 V.

PARALLEL BIAS RESISTOR
A 10Mi2 resistor is provided, shipped in a plastic bag with
the 109A, to be plugged into the two single pin sockets
near the lOOIVlJl resistor (R2) on the printed circuit. This
resistor will reduce the voltage required from the bias
supply, but should be used only for very high leakage
detectors. When it is instal led in parallel with R2, the total
series resistance between the Detector Bias connector and
the Detector Input connector is reduced to 10MJ2, and the
compensation is 10 V per microampere of detector leakage
current. However, this circuit will increase the zero pF
noise by approximately 0.5 keV (silicon equivalent) and
should not be used unless necessary. See Fig. 1.
4.2 Linear Output
The output of the 109A is a "step" of voltage of 150
mV/MeV with the gain switch in the X10 position, or
15 mV/MeV in the XI position (silicon detector equivalents).
The pulse rise time is a function of input capacitance (see
Fig. 2). The dynamic range of the output is 7 V either
polarity, when the output is "sending-end" terminated.
"Receiving-end" termination will result in a 3.5-V dynamic
range, but this may be preferable to sending-end termina
tion. The integral nonlinearity in the preamplifier is
specified at not greater than 0.1% over the 0- to 10-MeV
range.
EXT;
M EXT
EXT.
f'EXT
600_
10 20
50 100 200 500 ^ 000 2000 5000
Fig. 1. Bias Resistor Value (l\/112).
! i : i
::
— -----
--
1
-
/
/
/'
;
--
1
~r
/
/
/
I ! : ;
/
i
. : : 1
....
1
—
1
L|j 1 . .
*—
—
!
■ t-
109A
& 118
. . .
A
—
4 6 8 10 20 40 60 80 100
INPUT CAPACITANCE (pf|
400 600 1000
Fig. 2, Rise Time as a Function of Input Capacitance.

5. CIRCUIT DESCRIPTION (See Schematic Diagram 109A-0101-S1)
5.1 Charge-Sensitive Loop
The charge-sensitive loop consists of five transistors acting
as an operational amplifier with capacitive feedback.
Transistors Q1 and Q2 operate in cascade and drive Q3,
Q4, and Q5 in a low impedance driver configuration for low
output impedance and fast rise time. The rise time of the
charge-sensitive loop output increases as the external input
(detector) capacitance is increased. See Fig. 2.
5.2 Voltage Amplifier
The voltage ampl ifier is designed for fast rise time so as to
faithfully reproduce the pulse from the charge-sensitive
loop. In the XI0 gain position the gain is 3.4 and in the XI
gain position the gain is 0.34.
5.2.1 Pole-Zero-Cancellation Network The decay time con
stant of the output signal from the preamplifier is determined
by C12and the parallel combination of R17,R18, and R42.
It is accurately set at 50 fxs, R42, C12 is a 400-/JS time
constant in the proper configuration to provide a "zero"
type of frequency response which cancels out the 400-^ts
"pole" generated by the charge-sensitive loop feedback
time constant. The purpose of this "Pole-Zero Cancellation"
is to obtain a pulse response that has a step rise with a single
bO-fis decay time constant back to the basel ine without
appreciable undershoot. This will al low accurate pole-zero
cancel lation in the shaping ampl ifier.
5.3 Cable Driver
The cable driver consists of Q8,Q9, Q10, and Q11 operating
in a complementary Darlington connection. This circuit
gives extremely good l inearity and an output impedance of
a few ohms. However, 51^2 is Inserted in series with each
circuit, so that the minimum output impedance (R35 at
Ofi) is 51^2. The maximum output impedance is 150J2
(R31 at 10052), so that cables in the range of 50 to 15052
can be series (sending-end) terminated.
6. MAINTENANCE INSTRUCTIONS
6.1 Testing Performance
As ordinarily used in a counting or spectroscopy system,
the 109A is one part of a series system involving the source
of particles to be analyzed, the detector, the preampl ifier,
the main amplifier, and the pulse height analyzer. In
situations where proper results are not being obtained and
tests for proper performance of the preampl ifier and the
other components are indicated, it is important to real ize
that rapid and logical testing is possible only when the
individual components are separated from the series system.
In proving the performance of the preamplifier, this
consists of removing it from the system and dealing with it
alone, by providing a known electrical input signal and
testing for proper output signal with an oscil loscope.
6.1.1 Use a voltage pulse in the TEST PULSE jack, as out
lined in Section 3.4, or use a pulser with a charge terminator
as the DET. INPUT jack.
The polarity of the test pulse signal should be in agreement
with the expected signal input polarity from a detector.
6.1.2 If a suitable input signal has been obtained for the
109A as outl ined in the preceding section, its performance
may be checked by observing the pulse waveform at the
OUTPUT jack. If an input signal of 460 mV, corresponding
to about 10 MeV, has been obtained as described above,
one can expect an output pulse ampl itude of about 1.5 V
with the gain switch in the X10 position and 0.15 V with
the gain switch in the XI position.
6.1.3 The noise contribution of the preamplifier may be
verified by two basic methods. In either case, the normal
capacity of the detector and associated cables should be
replaced by a capacitor of equal value connected to the
DET. INPUT jack. This is necessary because the noise
contribution of the preamplifier is dependent upon input
capacity, as can be seen from the noise specifications given
in Section 2. The only meaningful statement of the noise
level of the preampl ifier is one that relates to the spread
caused by the noise in actual spectra. This can be measured
and expressed in terms of the full width at half maximum
(FWHM)ofa monoenergetic signal after passing through the
preamplifier and main ampl ifier system. The noise per
formance referenced in Section 2 is stated in these terms,
and verification methods will be described. If desired, the
preamplifier can be tested with no external capacity on the
DET. INPUT jack, in which case the noise width should be
approximately that shown for zero external capacity. In
any case, the input jack and capacitors, when used, should
be completely shielded electrical ly. A wrapping of aluminum
foil around the input jack wil l suffice for testing at zero
capacity.
The preamplifier must be tested in conjunction with an
associated main amplifier that provides the required pulse
shaping. The typical noise performance given in Section 2
is based on main amplifier pulse shaping consisting of equal
RC differentiation and integration of 2-/ts time constants.
For comparison to these tabulated values, it is preferable to
test the preampl ifier under identical pulse shaping con
ditions. It is also important to ensure that the noise level of
the input stage of the associated main amplifier does not
contribute materially to the total noise. This is usually
no problem provided that any input attenuators on the
main ampl ifier are set for minimum attenuation.

If a multichannel pulse height analyzer is used following
the main amplifier, the noise performance can be tested
merely by using a cal ibrated test pulse generator with
charge terminator, as outlined in Section 6.1.1. With only
the charge terminator connected to the DET. INPUT jack,
the spread of the pulser peak thus analyzed wil l be due
only to the electronic noise contribution of the preamplifier
and main amplifier. The analyzer can be calibrated in terms
of keV per channel by observing two different pulser peaks
of known energy, and the FWHM of a peak can be taken
directly from the analyzer readout.
It is also possible to determine the noise performance of
the preamplifier by the use of a wide-bandwidth rms ac
voltmeter such as the Hewlett-Packard 400D, reading the
main amplifier output noise level and correlating with the
expected pulse ampl itude per keV of input signal under the
same conditions. Again, a cal ibrated test pulse generator is
required for an accurate measurement. In this method the
preamplifier and main amplifier are set up as they would be
used normally, but with a dummy capacitor (or no capacity)
on the DET. INPUT jack, and with the ac voltmeter
connected to the ampl ifier output. The noise voltage
indicated by the meter, designated Efms, is read and noted.
Then, a test pulse of known energy, Ejn (in keV), is
applied to the input jack, and the amplitude of the result
ing output pulse, Eout. is measured in volts with an
oscilloscope. The noise spread can then be calculated from
the formula
FWHM (keV, Si det)
2.66 (Erms) (Ejp)
Eout
where Epms is output noise in volts on the 400D meter,
Ejn is input signal in keV particle energy, and Egyt is
output signal in volts corresponding to the above input. If
the gain of the shaping amplifier is adjusted so that the
output voltage is 2.66 V, then the meter reading will be
directly in keV FWHM except for a scale factor. [The
factor 2.66 is the product of two relations: correction from
rms to FWHM (2.35), and correction of the 400D meter
from sinewave to white noise (1.13).]
The noise performance of the preampl ifier, as measured by
the above methods, should not differ significantly from that
given in Section 2.
6.1.4 When testing the preamplifier and detector, if the
noise performance of the preamplifier has been verified
as outlined in the preceding section or is otherwise not
suspected, a detector may be tested to some extent by
duplicating the noise performance tests with the detector
connected in place, and with normal operating bias applied.
The resulting combined noise measurement, made either
with an analyzer or by the voltmeter method, indicates the
sum in quadrature of the separate noise sources of the am
plifier and the detector. In other words, the total noise is
given by (Ntot)^ = (Ndet)^ + (Nampl)^- Each quantity is
expressed in keV FWHM. The quantity N^et is known as the
"noise width" of the detector, and is included as one of the
specified parameters of each ORTEC semiconductor de
tector. By use of the above equation, and with a knowedge
of the noise of the preampl ifier, the noise width of the
detector can be determined. The significance of this noise
width in evaluating the detector is subject to interpretation,
but generally the actual resolution of the detector for pro
tons or electrons will be approximately the same as the noise
width; the resolution of the detector for alpha particles will
be poorer than the noise width. The most useful application
of determining the noise width of a detector is in the
occasional monitoring of this quantity to verify that the
detector characteristics have not undergone any significant
change during use.
6.2 Suggestions for Troubleshooting
If the preampl ifier is suspected of malfunctioning, it must
be isolated and tested alone, not in a system involving other
units such as a source of particles to be analyzed, the de
tector, the preamplifier, a main ampl ifier, and subsequent
sealers and/or analyzers. Such logical isolation and individual
testing of components wil l be the most productive approach.
6.2.1 Charge-Sensitive Loop The function of the preamp
lifier is simple and lends itself to relatively easy scrutiny.
The charge-sensitive loop performs a charge-to-voltage
conversion on the input signal. It has an output signal
that manifests itself as a fast rise (~15 ns at 0 pF external
capacitance) step of voltage whose height is determined by
the input charge, fol lowed by a 400-/is decay back to the
baseline. This signal can be observed at the emitter of Q4
while impressing a signal, as described in Section 3.4. The
ampl itude of thissignal should be45 mV per MeV equivalent
input signal.
6.2.2 Voltage Amplifier To reduce pulse pileup in the
voltage amplifier and subsequent stages, the output signal
from Q4 is differentiated with a 50-/xs time constant by
C12. Transistors Q6 and Q7 provide voltage amplification
of 0.34 or 3.4 for the XI or X10 gain switch positions,
respectively. Accordingly, the output signal at the 81
wiper arm should be a fast rise with 50-;tis time constant
decay, with amplitude either 0.34 or 3.4 times greater than
that at the Q4 emitter.
6.2.3 Cable Driver The cable driver, consisting of Q8
through Q11, is simply an impedance converter, and the
output signal should look exactly l ike the input signal. No
gain is obtained in the cable driver.
6.2.4 Table of DC Voltages The following l ist of voltages
will help to locate defective components. Exercise extreme
caution in making these measurements, because a probe
shorting two points on the printed board can cause great
damage.

Location
Jet.
R15
&
C9
Jet.
R28
&
C16
Jet.
R29
&
C15
Jet.
R16
&
C11
Q1
S
Actual
DC
Voltages
+
23.5
+
23.6
-
23.6
-
23.5
-
5.5
D
-
0.6
Q2
E
-
0.6
B
0
C
+
10.1
Q3
E
+
12.2
B
+
10.1
C
+
16.9
Q4
E
+
11.6
B
+
9.9
C
+
23.5
Q5
E
-
14.9
B
-
14.2
C
-
7.3
Q6
E
+
1.3
B
+
1.9
C
+
10.7
Q7
E
+
11.3
B
+
10.7
C
-
0.1
Q8
E
+
10.7
B
+
11.3
C
+
24.0
Q9
E
+
10.1
B
+
10.7
C
+
24.0
Q10
E
-
10.6
B
-
11.2
C
-
24.0
Q11
E
-
9.9
B
-
10.6
C
-
24.0
Note:
All
voltages
measured
with
vtvm
from
ground.

APPENDIX
REPLACEABLE PARTS
ORDERING INFORMATION
The Replaceable Parts List shown below contains informa
tion needed for ordering spare and/or replacement parts.
Each listing indicates the reference designator number, the
part number, a description of the component, and the part
manufacturer and manufacturer's part number.
Al l inquiries concerning spare and/or replacement parts and
all orders for same should include the model serial , and
revision ("Rev" on rear panel) numbers of the instruments
involved and should be addressed to the Customer Service
Department at 100 Midland Road, Oak Ridge, Tennessee
37830. The Manager of Customer Services can be reached
by telephone at [phone]. The minimum order for
spare and/or replacement parts is $25.00.
ORDERING INFORMATION
FOR PARTS NOT LISTED
In order to faci l itate the ordering of a part not l isted below,
the following information should be submitted to the
Customer Service Department:
1. the instrument model number,
2. the instrument serial number,
3. revision ("Rev" on rear panel) number,
4. a description of the part,
5. information as to the function and location of the part.
The sol id-state-device (diodes, transistors, and integrated circuits) types installed in your instrument
may differ from those shown in the schematic diagram and parts list. In such cases, necessary replace
ments can be made with either the type shown or the type actual ly installed in the instrument.
109A-0100
109A-0100 PREAMP CHAS ASM
Replaceable Parts List
_ ia9a-o2(T0~
REFDES PART NUMBER DESCRIPTION
9 097 <113390 CCN OGE UG I09<*/U M/NT-34 PLAT
9 097 <r2<»300 TERM SHORTING M/CHAIN ABE 31-017
9 097 662670 CONN SHV BLK HO AMP SCLE SOURCE
"9 094 412770 SW SPDTMNTR AEP MSTiOSO
loyA-dzoa "1098-0200 PC HI) ASM
KbFUbS PAHI NUHBbR DbSLRIPI lUN
C1
T?
C3
C5
~C6~
9 055
9 on
9 055
9 065
9 065
C7
C9
no
Cll
9 06 5
9 06 5
06 5
9 06 5
408560
"5T5790~
408560
"425390
409500
409480
409420
80
4094R0
409450
409480
1500 PF 6KV DISC CRL (S SOURCE)
l-O Rl- 5KV CbH CRL ZDHT55ri09 Cfl
1500 PF 6KV DISC CRL (S SOURCE)
T.0"PF"'5KV-CFR-CRl 2DHT55TT09"~CA~
22 UF 20% 15V SPR 1500226X0015B2
6.8 Ub 20% 35V SPm5OU685XOO3502
1 UF 20% 35V SPP 150D105X0035A2
6.8 UF 20% 35V SPR 150D685X0035B2
6.a"UF "20% 35V SPR150D685X0035B2
6.8 UF 20% 35V SPR1500685X003502
"CT2 9 059 408960 2000 PF MIC21! 500V ARC l)M19-202G
C13 9 065 409480 6.8 UF 20% 35V SPR1500685X0035B2
-n4 "9" Cr65-409450 6."5 tF 20% 35V "STRI50D685X0035BZ""
C15 9 065 409510 22 UF 10% 35V SPR I500226X9035R2
CT"6 9 0 6 5 409 510 22 UF 10% 35V"" S"PRn50TJ2"26X903 5R 2
C17 9 065 409480 6.8 UF 20% 35V SPRl500685X0035B2
~CT8 9 065 409480 6.8 UF 20% 35V SPR150U6B5X0U35H2
C19 9 065 409510 22 UF 10% 35V SPR 150D226X9035R2
""C70" "9""a^5 4"a95T0 22 UF ~I0% 35V SPP~I500226X9035R'r""
C21 9 065 409480 6.8 UF 20% 35V SPR 1500685X0035B2
C22 " 9 065 409480 "6; 8 UF 20% 35V"SPRr5OTT6"05XOO35B2
C23 9 057 408660 6.8 PP 5% IKV DISC SPR 10TCC-V68
P2
01
"U? "
03
"04—
05
"05"
07
Q9
Oil
9 078 4^8890 TKfiNS " MP56531 MUT StLECT RED
9 078 410900 TRANS-SFB1843 115-75 SPEC TII
" 9 07 8 436550 TR4N5—MUT "HPS-653T
9 078 436480 TRANS-MPS6543 MOT
"9 C78 436490 TRATIS "M"CTT"WPS-6520
9 078 410830 TRANS FSC 2N3643
9 078 47/9^0 TRANS - 2N3643 FSC SPEC RED
9 078 436500 TRANS MOT MPS-6534
'9""07B 41"0830 TRANS FSC "2N3^4T
9 078 410830 TRANS FSC 2N3643
9 078 410750 TR5W5-F5C~25[T63F
9 078 410750 TRANS FSC 2N3638
-r09A-0200 PC HD TSW"
RCFDES PARI NUMBER UESCRIPI ION
RI
112
IT
R5
iT6~
R7
RB
-59^—
RIO
K1 I
R15
-R16 '
R17
R18
R 19
B44
9 OIS
9 015
9 DJT
9 027
9 030
9 015
-9-030
9 015
9 027
9 015
9 015
9 027
""9" "077
9 015
402630 1 MOHM CC i/4W 5% ABC CB
402880 100 MOHM CC 1/4W 5% ABC CB
405 890 93.1 OHM MF 1/BW Tf "TRC" CEA T^—
405410 9.09 KOHM MF 1/8W 1% COW C4 T-0
25.5 KGHM~"MF" T/SW 1% TRC CEAH^Q^
417660 1.21^K0HM MF iy2W 1% CGW C-6
402880 lOO" MOHM CC 1/4W 5% ABC CB
406550 909 TTHM OF T/2W 1% IRC"-CFC
402570 100 KOHM CC 1/4W 5% ABC CB
405630 61.9 KUHH WF 1/HW 1% IRC LbA I-U
405510 15 KOHM MF 1/8W 1% IRC CEA T-0
UO 3.83 KUHM Mb i/8W 1% CGW L4 1-0
402020 10 OHM CC I/4W 5% ABC CB
402020 TO OHM CC 1/47? b% ABC CB
405990 P2.3 KOHM MF 1/8H 1% IRC CEA
T-0
40563O~6T79 KOHM Mb 1/8W 1% TRC" LEA
402400 5.6 KOHM CC 1/4W 5% ABC CB
T=cr
-R20 9 015 402690 6.2 KUHM CL i/4W 5% ABC CB
R21 9 015 402670 4.3 KOHM CC 1/4W 5% ABC CB
"P2? 9 02T-4O533O 4.64-KrmF"MF I78W 1% CGW C4
R23 9 027 405170 1.47 KOHM MF 1/8W 1% CGW 04
P24 9 027 405720 69"S " OHM mf iro-W-I% TRC "CTA"
R25 9 027 405590 38.3 KOHM MF 1/8W 1% IRC CEA
-R715 9 02/ 4U5MU /fe.B KOHM Mb i/BW 1% IHL LbA
R27 9 027 405590 38.3 KOHM MF 1/8M 1% IRC CEA
R28 9 OI5" 402020 1"0 l/4W- 5% ABC 'CB
R29 9 015 402020 10 OHM CC 1/4W 5% ABC CB
"TTJO" 9 015 403580 120 "KUFO* CC 1/4W"-5%""ABC "CB
R3I 9 015 402580 120 KOHM CC 1/4W 5% ABC CB
T =Tr
T-0
T-0
T-0
I-U
T-0
R32
9 015
4J2360
3.3 KUHM
LL
1/4W
5% ABL CB
R33
9 027 404840
51.1 OHM
MF
1/8W 1% CGW
C-4 T-0
R34
9
02 /
4n"4"R40 "57 .1 UHM
Mb
1/HW 1% CGW C-4 l-U
R35 9 051 407950
100 OHM
POT
1/4W
ARC FP
lOIM
" P36
9 015
402880 lOU "MOHM
CC
1/4W 5% ABC
CB
R37
9 01 5
402880 ICQ MOHM
CC
1/4W
5% ABC CB
1/4W 5% ADC CB
-I/4W 5% ABC CB
R39 9 015 402570 100 KOHM CC
-R40" 9 015 40Z5B0 120 KUHM""CC~
R41 9 017 443410 51 OHM I/2W 5% ABC EE
R42" " 9 027 406000" 20(n(aHM""MF~r/8W IT CG"W C4 T-
R43 9 015 402640 10 MOHM CC 1/4W 5% ABC CB
9 02 / 40^920 8.06 KOHM MF l/HW 1% IRC CEA l-U
9 090 412230 bbPRIIb HbAU FbX 56-590-65/48

.0015 \ I ^9-
rF,
Hf
10 Meq.> -.
>/OOMcg.
.ji /OO-^
k:?—vw-i
Dsr.
iNPur
.0015
GKV
20,00
C.//A€CiS
seA/s/rive loop
5KV
NPa
TEST
RULSE
SOJJ sec
CUP
[/OLTA&E
X/D
CABLE
POLe-ze/to
AMPuF/EH SAW
sw.
METiVOPj(
—I
OUTPUT
POT
e-F - ^00 Mcg.
L
(C
§
1
i
Q'
3
B
UNLESS OTHERWISE
SPECIFIED
DIMENSIONS IN INCHES
TOIERANCES
FRACTION +
DECIMAIS +
ANGLES ±
SURFACE FINISH s/ RMS
APPLIED PRACTICES
OAK RIDGE TECHNICAL ENTERPRISES CORPORATION
OAK RIDGE TENNESSEE
TITLE
BL.OOK O/AG/EAM
MODEL /OBA P/^EAMELIE/E/^
DRAFTSMAN DATE
CHECKED
iWFG. APPROVA^
DWG/ iSSIiSD
I12M
10.
U.e>. /9yers
DRAWING NO.
/OBA- O 10 ! -&/

C
I I
4-
o
©C4.
-C5Z>-
-|g-»oh
-+
czz
SPECIAL
CREO
DcT)
r
Q7
—I
g'SOl—
o
N
AV_\-
T
»-4
J
C.
O
;s
r>
G:
C.
T
i
O
rs
G.
X-S.

I
lO-rt
DCT.BM5 TEST INPUT
R5
3^9 <
R2I
4.3K
1/4W
Me&
MPS««I ,,4.^'''
25.5K
RZS
38.3K
93.l"«-
SOOpf
6k:v
6MV
PISC
KH
52.3K
t.ZiK
l*/o
//SW
MPSfe634
Qd
eM3643
e42
200 K
I lie
fe l.9<
3643
=• <^2
r MV565JI
5OOCV
2M3643
C19
22>UF
35V
SHIELP
l.OpF
<?44
8'ObK
OUTPUT
: 4.64lir
e43
10 MW
'/4W
5
R94
lOOM
1/41^
AV^
R 37
COM
//4W
A>A
R36
DISC.
NOTE
lOOM
/4W
5%
lOOM
i/4.tV lOOM
R35
lOOxu
1/4-W
QtO
2N36ae
R34- C20
S|./-r»- 22^r
35 V
r
ipoopf
6KV
6MV ^ ,
OjSC
Q I
4f090
Drr. iwPuT
eio
kOOIC
/4W
5«/»
bl-9 K
A^ERRi
C23 ,
6.5 p-f
PISC.
I OUT
ZZ7
3S-3K
PROTECTJON
CIRCUIT
(5eE NOTE 4^
S14
3.fl3K T
R9
909-^
IVp
'/2W
Q/Z
mpsc»531
40
\ZO\C
S'/o
tuvj
-2AV
I-ALW RESISTORS arc MCTAL FILM^ "/SW, I «/*, UNLESS OTHERW/Sl SPCCiFlEO-
2«ALL CAPACITORS ARC 35V TANTALUM^ UNLESS OTMCRWlSE SPEClFieo.
3-NUMBERS CD (g) © ® 60 TO AMPHEWOL CONNECTOR 17-ZOO90.
4-PKOTeCTlOU CIRCUIT MAr BE REV10VCO BV MOVIUlS THE PLU6-/W JUMPER FROM
''in" posir/o»* TO "our" position. C^ee iajstruction manual ''uotice" F=^«ey
5, D.M. INDICATES PIPPED MiCft.
* e. PARALLEL BIAS RESISTOR-SEE MANUAL 4J
7. Qfe- SeLECTED FOR L^SN NOISE, OR.TEC PPsRT ■** 4-1797
Nr-
08>
MUSS OTHCmitSE SPECEIEO
DWEWSKIRS IN HCHES
TOCEMNCES
NCORPORATED
100 MIDLAND ROAD. OAK RIDGE, TENNESSEE 37830
m
SCHEMATIC-MODEL I09A P/?EAMpL IF/ER
'una— »n
D-W£9B 4'll-L>8
9A-
U /Ayggs
i/tfHiyn, , iwrt
« v/
iKUftKD na m
I09A-0( 01 -SJ