Krohn-Hite S700 Operating instructions

0.002Hz TO 2MHz
FUNCTION GENERATOR
MODEL S700 SERIAL NO.

0.002Hz TO 2MHz
FUNCTION GENERATOR
MODEL 5/700 SERIAL NO.
OPERATING AND MAINTENANCE
MANUAL
W/L)
|
INSU
KROHN-HITE CORPORATION
AVON INDUSTRIAL PARK / BODWELL STREET/ AVON, MASS. 02322
(C) 1976 KROHN-HITE CORPORATION.

Contents
ee a
CONTENTS
Section Page
] GENERAL DESCRIPTION ......2- 22 - ee ee ees eee l
2
OPERATION
......
eee
eee
re
ee
4
3 INCOMING ACCEPTANCE AND PERFORMANCE
CHECK 1. www wee ttt ee we te tt tt et et eee 6
4 CIRCUIT DESCRIPTION .........-.2022 2c eee vevcrees 8
5 MAINTENANCE......... cee me etree ew we ee ee eee 13
6 CALIBRATION .... 2... eee eee ere ee eee ee eee . 19
ILLUSTRATIONS
Figure Page
1 Model 5700 Function Generator .... 0... e eee ee eee eee ii
2 Simplified Schematic Diagram ........22 cece ee evees 8
3 Triangle Generator ......... a a a re ‘ 9
4 Square Wave Generator .. 2... eee cece reer ee eerevevens 9
5 Sine Wave Shaper .....-. eee vere evr reer vere veee 10
6 Plus Output Amplifier ....... 02. 2 eee ee eee weer evens 10
7 Minus Output Amplifier ....... ww we ee eee ewe wwe 1]
8 Power Supply . 2... ce veer eee e rrr vn er eee rrr eres eves 1]
APPENDIX
Schematic Diagram, PC Board Component Layout, inside
Parts List 2. cece ew eee eee weer wee eee eee eee eves back
cover
TABLE
Table Page
] Troubleshooting Chart . 2... ee ee eee ene ee ee ee enna 13

Model 5700 Function Generator
Figure 1. Model 5700 Function Generator
- pute

Section 1 - General Description
SECTION 1
GENERAL DESCRIPTION
1.1 INTRODUCTION
The Krohn-Hite Model 5700 Function Generator provides sine, square or triangle
waveforms, over the frequency range of 0.002 Hz to 2 MHz. The frequency control
dial is calibrated in Hertz from 0.2 to 200, permitting 1000:1 tuning. The 5700
provides a 50 ohm single ended, 15 volts p-p open circuit output, and simultaneously,
a balanced 600 ohm, 30 volts p-p open circuit output. Both outputs are controlled by
a two position attenuator, calibrated in 40 dB steps, with a separate infinite resolu-
tion vernier. An additional 1 volt p-p auxiliary square wave output is also provided
on the 5700. |
The function generator is carefully inspected, aged, and adjusted before shipment,
and should be ready for operation when it is unpacked. If it appears to have been
damaged in shipment, make a claim with the carrier and notify Krohn-Hite im-
mediately. | : |
1.2 SPECIFICATIONS
Waveforms
Sine, square, triangle.
Frequency Range
0.002 Hz to 2 MHz in 4 ranges.
Frequency Control
Single turn dial calibrated logarithmically from 0.2 to 200 in Hertz, and a 4 position
multiplier providing a 1000:1 coverage in each multiplier position.
BAND MULTIPLIER FREQUENCY-RANGE (Hz)
] 0.01 0.002 - 2
2 ] 0.2 - 200
3 100 20 - 20K
4 10K 2K - 2M
Frequency Accuracy
+3% at four dial calibration settings of 0.2, 5, 50, 200.
+15% maximum at other settings.

Model 5700 Function Generator
Frequency Stability
10 minutes 0.05%
24 hours 0.25%
Vs line 0.01% for 10% line change
Vs temperature 0.05%/°C (-10°C to 50°C) from 0.002 Hz to 100 KHz.
Time Symmetry
Sine, square, triangle, 99% from 0.002 Hz to 100 KHz.
Main Output
Waveforms: Sine, square, triangle.
Output Characteristics:
50 ohm output: 15 volts p-p open circuit; 7.5 volts p-p across 50 ohms.
300 ohm outputs: 15 volts p-p open circuit; 7.5 volts p-p across 300 ohms.
600 ohm balanced output: 30 volts p-p open circuit; 15 volts p-p across 600 ohms;
balance greater than 60 dB to 20 KHz.
Isolation: Can be floated up to +500 volts peak between outputs and instrument
case,
Amplitude Stability (maximum amplitude):
10 minutes 0.02%
24 hours 0.1%
Amplitude Control: Two position attenuator, calibrated in 40 dB steps, with
separate infinite vernier. Attenuator accuracy is 0.2 dB. Minimum output is
less than 3 millivolts.
DC Components: All waveforms are symmetrical about ground with nominal zero
dc volts. At maximum output, drift is less than 5 millivolts /°C. Drift is
reduced in proportion to output attenuator setting.
Frequency Response: Sine wave, less than 0.1 dB from 0.002 Hz to 200 KHz;
0.5 dB to 2 MHz.
Sine Wave Distortion: Less than 0.5% from 0.002 Hz to 100 KHz; 3% to 2 MHz.
Square Wave: Rise and fall time less than 50 ns; total aberrations less than 5%
with 50 ohm termination.
Triangle Linearity: Greater than 99% from 0.002 Hz to 100 KHz; 95% to 2 MHz.
DC Offset: 0 to £5 volts open circuit. Stability 5 millivolts /°C, reduced in
proportion to attenuator setting. Maximum peak signal plus dc offset is +7. 5 volts.
Auxiliary Output
Fixed 1 volt p-p square wave. Impedance 200 ohms.
Operating Ambient Temperature Range
-10°C to 50°C.

section | - General Description
Controls
Front panel contains frequency dial, frequency range multiplier, amplitude
attenuator and vernier, main output waveform selector, dc offset, power switch.
Rear panel contains line switch, symmetry adjust, dc level adjustments.
Terminals
Front panel only, BNC connector for the 50 ohm output. Binding posts for the
600 ohm balanced output and auxiliary output.
Power Requirements
107-127 or 214-254, single phase, 50-400 Hz, 3.5 watts.
Dimensions and Weights
5 1/2" (140 mm) wide, 6'' (152 mm) high, 12" (305 mm) long; 7 lbs. (3.5 kg) net,
10 lbs. (5 kg) shipping.

Model 5700 Function Generator
SECTION 2
OPERATION
2.1 POWER REQUIREMENTS
The Model 5700 Function Generator may be used either with a 107-127 or 214-254
volt, 50-400 Hz line. The line voltage can be selected by operation of the line
switch on the rear panel. All units are shipped with the line switch in the 117 volt
position and a fuse bag attached to the line cord. The fuse bag contains a 1/16
ampere fuse. When 234 volt operation is required, replace the 1/8 ampere fuse
with the 1/16 ampere fuse and switch the line switch to the 234 volt position.
2.2 OPERATING CONTROLS AND CONNECTORS
2.2.1 Front Panel Controls
POWER: A 1 position pushbutton switch for selecting OFF-ON, and a pilot light
to indicate the ON condition.
FREQUENCY DIAL AND MULTIPLIER: Single turn dial, calibrated logarithmically
from 0.2 to 200 to provide 1000:1 frequency coverage in each of the 4 multiplier
switch positions, X0.01 to X10K.
WAVEFORM: 3 position pushbutton switch for selecting sine, square or triangle
waveforms.
AMPLITUDE: 2 position attenuator switch for selecting 0 dB and -40 dB, anda
separate infinite vernier for fine adjustment to an additional -60 dB. For low level
Signals, the output should be properly terminated.
DC OFFSET: Switch and potentiometer determines the de offset of the 50 ohm and
600 ohm balanced output signals by up to +5 volts open circuit. The dc offset, plus
the ac signal, should not exceed £7.5 volts peak, open circuit, or clipping will
occur.
2.2.2 Rear Panel Controls
LINE: 2 position switch for selection of 117 or 234 volt operation.
SYM ADJ: Potentiometer for periodic adjustment of the waveform symmetry.
DC OUTPUT LEVELS: 2 potentiometers for periodic adjustment of the + and -dc
output levels.
2.2.3 Connectors
50 OHM: The selected waveforms appear at this output. Impedance is 50 ohms.

Section 2 - Operation
600 OHM BALANCED: The selected waveforms appear at this output. Impedance
across the two red binding posts is 600 ohms. Impedance across either red and
black binding post is 300 ohms.
1 VOLT P-P: Fixed amplitude of 1 volt p-p square wave. Frequency is coincident
with the 50 ohm and 600 ohm balanced outputs. Impedance is 200 ohms.

Model 5700 Function Generator
SECTION 3
INCOMING ACCEPTANCE AND PERFORMANCE CHECK
3.1 INTRODUCTION
The following procedure should be used to verify that the generator is operating
within specifications, both for incoming inspection and for routine servicing.
Tests must be made with all covers in place and the procedure given below should
be followed in sequence. If a problem is encountered in the procedure that is given,
refer to Calibration, Section 6.
3.2 EQUIPMENT REQUIRED
(a) Oscilloscope, with 1 mv/cm sensitivity and bandwidth of at least 45 MHz,
Tektronix Type 7403N or equal, with 7B50 Time Base and 7A13 Differential
Comparator.
(b) Frequency counter, capable of measuring 0.002 Hz to 2 MHz.
(c) Distortion meter, Hewlett Packard, Type 333A or equivalent.
(d) Voltmeter, capable of measuring 0 to 20 volts.
3.3 PROCEDURE
After allowing the instrument to warm up for 30 minutes, set the controls to the
following positions:
POWER AC Operation
FREQUENCY DIAL AND MULTIPLIER 20 X100
ATTENUATOR O dB, vernier Max. CW
WAVEFORM Sine
DC OFFSET Off
3.3.1 Waveforms
Connect the 50 ohm output of the generator to the oscilloscope. Operate the Wave-
form pushbutton switch in all positions to check for the presence of all waveforms.
Return the switch to the sine wave position.
3.3.2 Attenuator
Rotate the Attenuator vernier to the max. CCW end. The signal should diminish
by more than 60 dB. Rotate the vernier to the max. CW end. The output ampli-
tude should be greater than 15 volts peak to peak. Connect the oscilloscope to the

Section 3 - Incoming Acceptance and Performance Check
ee
600 ohm Balanced output. The output amplitude should be greater than 30 volts
peak to peak. When operating the generator at a high frequency and the oscil-
loscope is connected to the 600 ohm balanced output, the oscilloscope should have
a balanced input to prevent the waveforms from becoming distorted, because the
outputs are floating from the chassis.
Operate the Attenuator switch, starting at 0 dB and going to -40 dB, reading the
output amplitude with an acvm. The Attenuator accuracy is +0.2 dB.
3.3.3 DC Output Levels
Set the Attenuator switch to the 0 dB position and the vernier to the max. CCW end.
Connect the dcvm between the black and the upper 600 ohm red binding posts. It
should be possible to set the level to zero by means of the +OUTPUT DC LEVEL
potentiometer, located on the rear panel. Connect the dcvm between the black
and the lower 600 ohm red binding posts. It should be possible to set the level to
zero by means of the -OUTPUT DC LEVEL potentiometer, also located on the
rear panel.
The output dc levels may change by approximately 10 millivolts when the Attenuator
vernier is rotated to the CW end. Therefore, it may be necessary to readjust the
+ and - OUTPUT DC LEVEL potentiometers for zero volts at the desired
Attenuator setting.
3.3.4 DC Offset
With the Attenuator vernier rotated to the CCW end, connect the dcvm to the
50 ohm output. Set the DC Offset switch to the IN position. The DC Offset control
should be capable of offsetting the signal by +5 volts, open circuit. Set the switch
to the OFF position.
3.3.5 Frequency Accuracy
Set the Attenuator switch to 0 dB position, vernier to max. CW end. Connect the
frequency counter to the 50 ohm output. The frequency accuracy should be +3
percent at the dial settings of 0.2, 5, 50 and 200; +15 percent maximum at other
settings.
3.3.6 Distortion
With the Waveform switch set to sine, and the frequency set to 0.2 X10K, check
the sine wave distortion using the distortion meter. Adjust the Symmetry Control
on the rear panel for a distortion reading of less than 0.5 percent.
3.3.7 Auxiliary 1V P-P
Connect the oscilloscope to the 1V p-pSquare Wave Output. Check that the square
wave is present and is at least 1 volt peak to peak open circuit.

Model 5700 Function Generator
Ree
SECTION 4
CIRCUIT DESCRIPTION
4.1 SYSTEM OPERATION
R
TUNING 50n.
rr OUTPUT
—
ATT.
-—O
- GEN.
GEN I S
TO ATT. 5
| VU 600.0.
fr! BAL. 7
Cc SHAPER OUTPUT
AO
Figure 2. Simplified Schematic Diagram
A simplified schematic diagram of the function generator is shown in Figure 2.
The basic oscillating system is comprised of a square wave generator and triangle
generator, with the frequency controlled by the frequency dial potentiometer and
the R and C multipliers. This system generates the square wave and the triangle
wave, which is further processed to form the sine wave. The frequency control
dial varies the amplitude of the square wave applied to the input of the triangle
generator. The square wave is applied to the triangle generator input, through
the network R, charging and discharging the integrating capacitor C in accordance
with the time constant determined by the amplitude of the square wave, the R net-
work, and the integrating capacitor. The output of the triangle generator is used
as the input for the sine wave generator, and regeneratively as a trigger for the
square wave generator. It is also fed directly to the waveform switch for the
triangle function.
The output of the sine wave generator and the square wave generator are also both
fed directly to the waveform switch for the sine and square functions. The square
wave is attenuated and fed directly to the auxiliary output.
The + output amplifier inverts its input and provides the low impedance for the
attenuator and 50 ohm output. The + output amplifier is also used as an input for
the - output amplifier, which inverts its input, and simultaneously with the + output,
they provide the signal for the attenuator and the balanced 600 ohm output.

Section 4 - Circuit Description
4.2 TRIANGLE GENERATOR (See Figure 3)
SO
TUNING >. TO
Figure 3. Triangle Generator
The triangle generator is an inverting infinite gain amplifier, with a feedback
Capacitor C to provide the integrating function. The triangle generator consists of
an input stage, Q9, a second stage, Q10-Q11, an output amplifier stage, Q12-Q13-
Q14, and an output emitter follower stage, Q15-Q16.
Q9B and Q10 form a high gain regenerative stage. The emitter follower driver,
Qi2, feeds the output amplifier stage, Q13-Q14. Q13-Q14 feed the two emitter
follower transistors, Q15-Q16, which provides a low impedance triangle output.
Capacitor C is selected by the bandswitch.
4.3 SQUARE WAVE GENERATOR (See Figure 4)
+11V
RI40
CR27 CR28
o> TUNING
TRIANGLE
_
—_—RIS2
028
Q30
Q32
OSA
GENERATOR
Q29
Q3I
Q33
O
CR25
CR
26
SO
Figure 4. Square Wave Generator
The output of the triangle generator triggers the square wave generator. Dif-
ferential amplifiers, Q28-Q29 and Q30-Q31, form a regenerative sense amplifier,
with a feedback path from the collector of Q30, thru CR27 and CR28 to the base of
Q28. When the peak of the triangle reaches -7.5 volts, Q28 conducts, turning on
Q30, forward biasing diode CR28, reverse biasing CR27, and disconnecting R140
from the base of Q28. Q28 remains on as the triangle voltage goes from -7.5 to
+7.5 volts. When the triangle reaches its positive peak of + 7.5 volts, the base of
Q28 goes positive, turning off Q28 and Q30, reverse biasing CR2Z8, and connecting
R140 to the base of Q28. The voltage at the base of Q28 is limited to plus or minus

Model 5700 Function Generator
ee
0.6 volts by the action of CR25 and CR26. When the triangle again reaches -7.5
volts, the cycle repeats. The 1 V p-p square waves that are developed at the col-
lector of 031 and the collector divider of Q28 drive the switching transistors, Q32
and Q33. The collectors of Q32 and Q33 provide a 22 V p-p square wave for the
tuning pot, the auxiliary square wave output divider, and the divider network to
the emitter follower transistors, Q34-Q35, providing a low impedance square
wave output with reduced amplitude.
4.4 SINE WAVE SHAPER (See Figure 5)
TRIANGLE DIODE NETWORK
>—
GENERATOR 0102
é—»>——() AO
Figure 5. Sine Wave Shaper
The sine shaper consists of five pairs of diodes, each pair associated with a voltage
divider. The function of the voltage divider is twofold: (1) it changes the slope of
the input signal, and (2) it sets the level at which the diodes clip the signal. Thus
when the triangle is applied to the circuit, the divider resistance changes its slope
and the diodes clip it at five discrete increments within each 90 degrees. The
resultant waveform approximates a sine wave. The main purpose of QI and Qé2 is
to provide the dc voltages to which the diodes clip. The thermal drift of QI and Q2
also cancels the thermal drift of the diodes. Potentiometers R20 and R21 are ad-
justed to minimize distortion. The output of the sine shaper is applied to the base
of Q3 through the feedback network. The balanced input amplifier Q3-Q4 drives the
second amplifier stage, Q5-Q6. Q5-Q6 drives the two emitter follower transistors,
Q7-Q8, providing a low impedance sine wave output.
4.5 PLUS OUTPUT AMPLIFIER (See Figure 6)
WAVEFORM Mi
SWITCH
RI7I
AMPLITUDE
Q38
Q39
Figure 6. Plus Output Amplifier
The input signal for the plus output amplifier is controlled by the amplitude vernier
R171, and is applied to the base of Q36. Q36-Q37 is a balanced input amplifier,
Which drives the output amplifier stages, Q40 and Q41 at low frequencies. At
higher frequencies, additional drive signal is provided thru Q38-Q39 to Q40-Q41.
Q40-Q41 feed the two emitter follower transistors, Q42-Q43, providing a low
impedance source for the input of the minus output amplifier, and both the 50 ohm
attenuator and the positive balanced 600 ohm attenuator,
10

Section 4 - Circuit Description
Ease
4.6 MINUS OUTPUT AMPLIFIER (See Figure 7)
MO > Q44 Q48
Q45
Q46
Q49
>——CE)
BO
Q 47
Figure 7, Minus Output Amplifier
The input signal level for the minus output amplifier is provided by the output of
the plus output amplifier, and is applied to the base of Q44. Q44-Q45 is a balanced
input amplifier, which drives the output amplifier stage, Q48 and Q49 at low fre-
quencies. At higher frequencies, additional drive signal is provided thru Q46-Q47
to Q48-Q49. Q48-Q49 feed the two emitter follower transistors, Q50-Q5l, pro-
viding a low impedance source for the negative balanced attenuator.
4.7 POWER SUPPLY (See Figure 8)
+UNREG > ® >+11V
Ril
Rlil2
—UNREG
Figure 8. Power Supply
The power supply provides positive and negative 11 volts of regulated power to all
circuits. Transistor Q27 is used as a 6.5 volt zener, and is the reference in the
negative supply. Q27 determines the emitter voltage of the common emitter stage,
Q25-Q26. Any change in the -11 volt supply is sensed by the base of Q26 through
the reference zener Q27. Q25-Q26 drive the second common emitter stage Q23-
Q24, driving the series regulator Q22. A short circuit in the minus supply will
turn off Q23 and Q24, turning off Q22, thus providing short circuit protection.
11

Model 5700 Function Generator
The positive supply uses the -11 volt supply as a reference. Any change in the +11
volt supply is sensed at the base of Q21 through the divider RI11-R1I12. Q20-Q21
drive the common emitter stage Q18-Q19, driving the series regulator Q17.
A short circuit in the plus supply will turn off Q18 and Q19, turning off Q17, thus
providing short circuit protection.
12

Section 5 - Maintenance
SECTION 5
MAINTENANCE
5.1 INTRODUCTION
If the generator is not functioning properly and requires service, the following
procedure may facilitate locating the source of the trouble. Access to the interior
of the generator is accomplished by removing the four screws centered at the rear
of each cover; sliding off the side covers will unlock the top and bottom covers.
When a malfunction is detected, first check the line voltage and line fuse, and then
make an inspection for broken wires, burnt or loose components, poor solder
joints or similar conditions which could cause the trouble. Before beginning
troubleshooting, it should be determined if the normal adjustments mentioned in
the Calibration and Adjustment procedure, Section 6, will correct the trouble.
Any troubleshooting of the generator will be greatly simplified if there is an under-
standing of the operation of the circuit: reference should be made to the Circuit
Description, Section 5,
5.2 TROUBLESHOOTING PROCEDURE
Set the controls to the following positions:
POWER On
FREQUENCY DIAL AND MULTIPLIER 200 X100
ATTENUATOR O dB, vernier Max. CW
WAVEFORM Square
DC OFFSET Off
Table 1 is provided to localize the defective circuitry:
Table 1. Troubleshooting Chart
Faulty Circuitry Troubleshooting
Symptom Check and/or Assoc. Comp. Section
I. (a) No signal at 50 Power Supply
ohm, Balanced 600| Voltages (-11V and
ohm or Auxiliary + 11V)
Output
(b) Power Supply Power Supply . 5.3
Voltages Incorrect
(c) Power Supply Polarity at TI should
Voltages Correct be opposite that at
TO
13

Model 5700 Function Generator
Table 1.
Troubleshooting Chart (Continued)
Symptom
Check
Faulty Circuitry
and/or Assoc. Comp.
Troubleshooting
Section
(d) If not Opposite
(e) If Opposite
Triangle Generator
Square Wave
Generator
5.5
5.4
(a) No signal at 50
ohm or Balanced 600
ohm Output; Auxil-
iary Output Normal |
(b) MIs ignal
Incorrect
(c) MI signal
Correct
(d) MO signal
Incorrect
(e) MO signal
Correct
Signal at input of
+ Output (7V p-p)
Amplifier (MI)
Signal at MO
(15V p-p)
Waveform Switch
+ Output
Amplifier
Attenuator
(a) No signal at
-600 ohm Output;
+ 600 ohm,
50 ohm and Auxil-
iary Outputs
Normal
(b) BO signal
Incorrect
(c) BO signal
Correct
Signal at output
of - Output
Amplifier (BO)
(15V p-p)
- Output Amplifier
Attenuator
5.8
(a) No Sine Wave
Output at 50 ohm
or Balanced 600
ohm Outputs;
Triangle and
Square Wave
Outputs are Normal
(b) AO Signal
Correct
(c) AO Signal
Incorrect
Signal at AO
(7V p-p)
Waveform Switch
Sine Wave Shaper
14