Ailtech 7320, 7310 Service manual

OPERATION AND SERVICE MANU AL

----------

7310

73 20

SYSTEM N O I SE M 0N I T0RS

> 4I UECH

DIVISION CUTLER-HAMMER

WARRANTY

Except for tubes, fuses, and batteries which carry no warranty,
Cutler-Hammer, in connection with equipment sold, agrees to correct any
defect in workmanship or material which may develop during the period of
one year from the date of shipment under proper or normal use and not in
excess of the original manufacturer’s life expectancy ratings, by its option
to repair or replace, FOB point of shipment, the defective part or parts,
and such correction shall constitute a fulfillment of all Cutler-Hammer

liabilities in respect to said apparatus.

July 1978

Chapter I-General Information

1-1. Introduction 1-1
1-3. General Description 1-1
1-7. Safety Precautions 1-1
1-10. Technical Specifications • 1-1
1-12. Functional Description 1-5

1-13. General 1-5

1-15. The Noise Monitor in a Typical Application 1-5
1-17. Auxiliary Outputs 1-6
1-19. Options 1-6
1-21. Accessories 1-7

1-22. Noise Generators 1-7

1-23. Precision Attenuation 1-9

1-24. Test Equipment 1-10

Chapter II--Installation

TABLE OF CONTENTS

Page

2-1. Introduction 2-1
2-3. Unpacking, Inspection and Damage Claims 2-1
2-5. Ancillary Items 2-1
2-7. Rack Mounting 2-1
2-9. Preparation for Use 2-1

2-11. Initial Checkout 2-2

2-14. General 2-2

2-16. Checkout Procedures 2-2

Chapter Ill-Operating Instructions

3-1. General 3-1
3-3. Description of Operating Controls, Indicators and Connectors 3-1
3-5. Set-up Procedures 3-1
3-8. Interconnections " ' 3-1
3-17. Excess Noise Ratio Setting 3-5
3-21. Establishing the Correct Signal Levels 3-5
3-27. Operation 3-7

i

3-31. Use of Auxiliary Outputs 3-9

3-33. Signal Monitor, Jl, Pin 4 3-9
3-35. External Meter, Jl, Pins 6 and 7 3-9
3-37. Recorder Output, Jl, Pin 8 3-10

3-39. Manual Noise Figure (Temperature) Measurements . 3-10

Chapter IV-Theory of Operation

4-1. Introduction 4-1
4-3. General Theory 4-1

4-4. Noise Figure Theory 4-1
4-6. Noise Figure Measurement 4-2

4-8. Operating Noise Figure and Temperature Measurement 4-4
4-11. Functional Description (Automatic Noise Measurement) 4-5
4-15. Circuit Descriptions 4-8

4-17. IF Amplifier 4-9

4-22. Square Law Detector 4-9
4-24. Variable Gain Amplifier 4-9
4-25. Synchronous Integrator and Meter Amplifier 4-9
4-26. AGC Amplifier 4-9
4-31. Timing Signal Generator 4-10

4-39. Power Supply Board . 4-13

4-41. +12 Volt Regulator 4-14
4-42. -12 Volt Regulator 4-14
4-43> +28 Volt Noise Source Supply: 4-14

Page

Chapter V-Maintenance and Adjustments

5-1. General 5-1
5-3. Performance Verification 5-1

5-6. Minimum Operating Level 5-1
5-7. Noise Generator Power 5-2

5-8. Accuracy 5-2
5-10. Checks and Adjustments 5-3
5-13. Power Supply Adjustments 5-5
5-14. IF Adjustments 5-5

. 5-16. Preliminary 5-5

5-17. Procedure ' 5-6

ii

Page

5-18. Meter Adjustments 5-6
5-20. Auxiliary Output Adjustments 5-6

5-22. Signal Monitor 5-6

5-23. Recorder Output 5-7
5-24. Troubleshooting 5-7
5-26. General Information 5-7

5-27. Tools 5-7

5-28. Transistors 5-7

5-29. Integrated Circuits 5-8

5-30. Logic Family 5-8

5-31. Logic Circuits 5-8

5-32. Analog Gates 5-8

5-33. Operational Amplifiers 5-8

5-34. Printed Circuit Boards 5-8

5-37. Printed Circuit Board Connectors 5-8

5-38. Front Panel Lamps 5-13

5-39. ENR Thumbwheel Switch 5-14
5-40. Troubleshooting Procedures 5-14
5-44. Factory Service 5-14

Chapter VI--Spare Parts

6-1. General 6-1

6-2. Recommended Spare Parts 6-1
6-3. Replaceable Spare Parts 6-1

iii

LIST OF ILLUSTRATIONS

Figure
Frontis

piece
1-1
1-2 SNM, Models 7310 and Outline Dimensions
1-3 SNM, Models 7320 Outline Dimensions
1-4

1-5
1-6
1-7
1-8

3-1 7310/7320 SNM Control, Indicator, Connector Locations
3-2 Bench Measurement Set-ups
3-3

3-4 Illustration of Sensitivity and Signal Level Range
3-5 Location of the Manual-Auto Controls
3-6 AILTECH Noise Figure Slide Rule
3-7

System Noise Monitors 1-2

Typical Noise Figure Measurement Set-up Using the AILTECH

7300 System Noise Monitors
Layout of J1 1-6

Typical Noise Sources Used with the 7300 SNM’S

Maximum ENR vs Frequency 1-9

AILTECH 32 Precision Attenuator (Cased Version)

Typical “ Operating” Measurement Set-up

Nomograph for Determining Noise Figure or Temperature

Page

1-3
1-3

1-5

1-8

1-10

3-3

3-4
3-4
3-6

3-8

3-10
3-11

4-1 Equivalent Noise Representation of a Noisy Network 4-3
4-2
4-3 Equivalent Representation of an Operating Noise Measurement
4-4 Functional Block Diagram
4-5 Timing Signal Generator Simplified Schematic and Timing Diagram

5-1
5-2 Adjustment Locations 5-4
5-3 Plastic-Case Transistors 5-7
5-4

5-5 Integrated Circuits Functional Illustrations 5-11
5-6 3-Input NOR Gate Operation
5-7 Operation of the COS/MOS Bilateral Switch

5-8 Typical Applications of Operational Amplifiers

5-9
5-10 General Troubleshooting/Repair Flow Chart
5-11
5-12

Equivalent Representation of Noise Figure Measurement Set-up 4-3

4-4

4-5

4-11

Set-up for Checking SNM Accuracy

Integrated Circuit Case Styles

Pin Numbering Layout of a Typical AMP 87133 Connector

IF Troubleshooting Chart
AGC Troubleshooting Chart

5-3

5-9

5-12
5-12
5-13
5-13
5-15
5-17

5-18

iv

Figure

5-13 Video-DC Troubleshooting Chart 5-19

5-14 Timing Generator Troubleshooting Chart 5-20
5-15 Power Supply Troubleshooting Chart 5-21
5-16 Power Supply, Parts Location and Schematic Diagrams 5-22
5-17 IF-Video Parts Location and Schematic Diagrams 5-25
5-18 Wiring Diagram 5-27

LIST OF TABLES

Table Page

1-1 Technical Specifications 1-4
1-2 Applicable Noise Sources 1-7
1-3 Recommended Test Equipment 1-10

3-1 AILTECH 7310/7320 System Noise Monitors Controls,

Indicators and Connectors 3-2

4-1 Functional Illustration — Timing and Gating 4-8
4-2 3-Input NOR Circuit Truth Table 4-13

5-1 Test Equipment Required for Performance Verification 5-1
5-2 Power Supply Checks and Adjustments 5-5

v/ vi

CHAPTER I

GENERAL

1-1. INTRODUCTION

1-2. This Instruction Manual is for the AILTECH 7310 and AILTECH 7320 System Noise Mon
itors (SNM), figure 1-1, and contains physical and functional descriptions, installation and inspec
tion procedures, operating and maintenance instructions, and a parts list for each model. All
schematics, electrical and assembly drawings are included, as are appendices for the available option
al features. Unless otherwise stated, the information provided herein applies to both models.

1-3. GENERAL DESCRIPTION

1-4. The System Noise Monitors described in this Instruction Manual (7310 and 7320) are
functionally identical. Each provides a readout of the Noise Figure of a unit under test (UUT)
when connected in a valid measurement setup. The minimum test setup consists of a SNM, the
UUT, and a solid state noise source of the AILTECH 7600 series. The 7310 and 7320 have op
tional meter scales which provide an Operating Noise Temperature readout in lieu of Noise Figure.

1-5. The 7310 and 7320 SNM’s are referred to as analog units because the readout is by a meter
with two ranges. Range selection is made by means of a front panel switch. AILTECH also manu
factures the 7360 and 7370 which indicate Noise Figure by means of a three-digit LED display
and are generally referred to as digital units.

1-6. The 7310 (Figure 1-2) is 7V& inches wide and is intended for bench-top use while the 7320

(Figure 1-3) is approximately 17 inches wide and is intended for rack mounting. The optional
Rack Mount Angle Brackets (Option 11) must be attached for mounting in a standard 19 inch
rack.

1-7. SAFETY PRECAUTIONS

1-8. The SNM’s are a low power instrument but when the unit is opened for service, there is the
possibility of contacting the A.C. line. The potential hazard is reduced by covering all exposed >
contact points with insulating material. These instruments should be serviced by technically quali
fied personnel only.

1-9. A standard three-wire, polarized line cord is supplied with the instrument and mates with
an internationally accepted EMI/RFI line filter. The connector complies with all current and
proposed domestic and international requirements for commercial test equipment.

1-10. TECHNICAL SPECIFICATIONS

1-11. A listing of technical specifications is provided in Table 1-1. Outline illustrations for both
models are presented in Figure 1-2 and 1-3.

1- 1

a) AILTECH 7320

1- 2

b) AILTECH 7310

Figure 1-1 . System Noise Mon itor s'

T

5 V4'

Jl

I

13 1/4 '

14 7/8'

SIDE

-iJ-

Figure 1-2. SNM, Models 7310 and Outline Dimensions

17"

T

5 1/4"

Jl

Figure 1-3. SNM, Models 7320 Outline Dimensions

TABLE 1-1. TECHNICAL SPECIFICATIONS

Input Frequency ,

Bandwidth

Minimum Operating Level

(Note 1)

Signal Level Range (Note 2)

Input Impedance

Accuracy (Note 3)

Meter Ranges

10.7, 21.4, 30, |36,¡45, 60 or 70 MHz
(to be specified at time of order)

10% of center frequency (nominal)

Less than -70 dBm

40 dB (minimum)

50 ohms (nominal); 75 ohms, optional if
specified at time of order.

Full scale to half scale:

±0.25 dB (Noise Figure)
±5% (Noise Temperature)

Half scale to quarter scale:

±0.5 dB (Noise Figure)
±8% (Noise Temperature)

0 and 6 dB full scale (Noise Figure),
60 and 240 kelvins full scale (Noise
Temperature). Extension to infinity
on all scales. »

Excess Noise Ratio

Calibration Range

Noise Generator Power

Recorder Output

Auxiliary Output Connector

(Recorder, Signal Monitor
and All Options)

Input Power

Dimensions

7310

7320

6 to 15.9 dB

Sufficient to drive all AILTECH Series 76
Solid-State Noise Sources

1 volt across IK ohms nominal for full
scale meter deflection.

Amphenol 57-20240-1, mates with
Amphenol 57-30240 supplied with unit
(see para. 1-17).

115/230 VAC ±15%, 50-400 Hz, 10 Watts

5 1/4”H x 7 7/16”W x 13 1/4”D (less
handles)(13.3 x 18.9 x 34.3 cm)

5 1/4”H x 17”W x 13 1/4”D (less handles)
(13.3 x 43.2 x 34.3 cm)
See Figures 1-2 and 1-3.

TABLE 1-1. TECHNICAL SPECIFICATIONS (continued)

Weight

7310 10 lbs. Net (4.5 kg)

7320 15 lbs. Net (6.8 kg)

NOTES:

1. Lowest noise input level (noise source off), at which valid automatic measurements
may be performed.

2. Range of noise levels (including Y-factor) over which valid measurements may be
performed.

3. Accuracy in the automatic mode is defined as the maximum permissible deviation from
a manual measurement made under the same conditions.

1-12. FUNCTIONAL DESCRIPTION

1-13. General

14 lbs. Shipped (6.3 kg)

19 lbs. Shipped (8.6 kg)

1-14. The System Noise Monitors are designed for both field and production applications where

simplicity and high accuracy instrumentation are required. The SNM’s are capable of providing fully
automatic testing via a continuous indication of noise performance for a variety of components,
assemblies and receivers. Simplified functional operation of the SNM’s is described in the typical
applications presented in the following paragraphs; a detailed functional description is provided in
Section IV. All AILTECH solid state noise sources from 10 MHz to 18 GHz are usable with the
SNM’s described herein (see paragraph 1-23).

1-15. The System Noise Monitor in a Typical Application

1-16. In a typical measurement set-up for transistors, amplifiers, mixers, receivers, etc. such as
that shown in Figure 1-4, the SNM furnishes modulated low level DC power to the noise source,
which in turn provides alternating noise-on and noise-off periods to the unit under test (UUT).

Figure 1-4. Typical Noise Figure Measurement Set-up Using

the AILTECH 7300 System Noise Monitors

1 - 5

An intermediate frequency (IF) is derived either internal to the UUT in the case of a complete
transceiver or externally by means of added downconverters. This signal, which consists of periods
of IF noise from the UUT alone, alternating with periods of UUT noise plus that added by the
noise source, is applied to the SNM input. The difference between the two detected levels derived
from the IF signal is related to the noise performance of the UUT. This difference is synchro
nously detected and displayed directly as noise figure or noise temperature by the SNM.

1-17. AUXILIARY OUTPUTS

1-18. Several auxiliary outputs for remote monitoring or record keeping are available at Jl, a
multipin connector on the rear panel. The layout of Jl is shown in Figure 1-5. The outputs
available are as follows:

a. Alarm Relay. An optional (Option 03) variable threshold alarm relay, applicable to

all models.

b. Signal Monitor. A DC signal that varies from 0 to 6 volts (nominal) as the input IF

level increases from the sensitivity limit to 50 dB above that limit. This is a non
linear output intended only to indicate signal level.

c. External Meter. A meter with 100 microamps full-scale sensitivity connected across

pins 6 and 7 of Jl will track the excursion of the SNM front-panel meter. When
Option 12, 10 volt recorder output, is installed the External Meter Function is not
available.

d. Recorder Output. One volt into 1 K ohm for full scale deflection of the front panel

meter.

J1

O O

o o

O 0
o o
o o
o o
O 0

O 0
o o
o o
O 0

13 ^

......

►

— b

— ►

1— ►

— »

— ^

24

• I
>

NOT USED

OPTIONAL

ALARM RELAY

SIGNAL MONITOR

SIGNAL GND

EXT. METER (-)

EXT. METER (+)

RECORDER OUTPUT

NOT USED

1

SW
NO

« - O 0

NC

4 —

•4—
< #-

4 —

12

Figure 1-5. Layout of Jl

1-19. OPTIONS

1-20. The following options are available for the 7300 System Noise Monitors and are listed here
for reference and identification purposes. See the referenced appendices or documents for com
plete option descriptions. .

1- 6

a. Option 02, Radar Noise Monitor. Applicable to the 7320 SNM only. Provides for

continuous, on-line, noise performance monitoring of an operating radar without

interfering with the radar operation. Option 02 is covered in a separate manual.

b. Option 03, Alarm Indication. Applicable to both models. SPDT relay deenergizes

when the measured noise figure degrades beyond a preset limit. The threshold is
continuously variable from inside the unit. The relay contacts are available at J1
(see Figure 1-5). Refer to Appendix B.

c. Option 06, Special Paint. Applicable to both models. Front panels can be painted in

accordance to customer’s specifications (with customer supplied paint).

d. Option 07, High Sensitivity. Applicable to the 7320 SNM only. Improves the sensi

tivity to -100 dBm. Refer to Appendix C.

e. Option 09, Broadband Mixer Input. Available on 7320 SNM only. Addition of a

broadband, mixer with all ports (RF, LO, IF) available at the rear panel. The mixer
cover 10 to 1,000 MHz. Refer to Appendix D.

f. Option 10, Front Panel Controls for Manual Operation. Applicable to both models.

The controls required for manual Y-factor measurement are moved to the front panel.
Refer to Appendix E.

g. Option 11, Rack Adaptor Brackets. Applicable to the 7320 SNM only. Permits

mating the front panel with a standard 19 inch rack. See Appendix F.

1-21. ACCESSORIES

1-22. Noise Generators. A complete measurement setup requires a noise generator in addition to

the SNM. All 7300 SNM’s are designed to operate with solid-state noise sources of the 7600 series.

Table 1-2 lists the applicable sources and Figure 1-6 illustrates some typical noise generators.

TABLE 1-2. APPLICABLE NOISE SOURCES

Part Number 07615 07616

Frequency Range

(GHz)

Excess Noise Ratio

(dB)

Calibration Freq.

(GHz)

ENR Accuracy (3) (dB)

VSWR (maximum) 1.2 1.2

0.01-1.5 1-12.4 12.4-18

15.5±0.5

0.03, 0.3,

1.0,1.5

±0.3 ±0.3 ±0.25

15.5±0.5 15.5±1

1,2,3.95,

8.2, 12.4

07617

12.4,15,18,

1.3

7650-X (1) 7660-X (1)

(2) (2)

see
figure 1-7

3 points specified at
time of order

±0.5(4)

4:1

see
figure 1-7

±0.5(4)

4:1

Output Connector

N male

N male

Table continued on page 1-8

OSM female Type N-male

OSM-female

1 -7

TABLE 1-2. APPLICABLE NOISE SOURCES (Continued)
Part Number
Input Connector BNC female
Input Requirements 28 volts at

07615 07616 07617

less than

30 mA

BNC female
28 volts at

less than
30 mA

BNC female
28 volts at

less than
30 mA

7650-X (1) 7660-X (1)
BNC female BNC female

28.0 V at
30 mA
maximum

28.0 V at
30 mA
maximum

NOTES:

1. Last digit assigned to each specific noise source at time of order.

2. Up to 15% of the center frequency from 10 MHz to 18 GHz — wider bandwidths available.

3. Accuracy of the ENR data supplied at the calibration frequencies.

4. Higher accuracy available.

a) 07615 10 to 1500 MHz

b) 07616 1 to 12.4 GHz

. S/M 2 0 9 ,

BIAS 28.00 VDC

’u r n NOISE GENÉ51Ï * *

c) 07617 12.4 to 18 GHz

d) 07660 Typical High Level System Noise Source

Figure 1-6. Typical Noise Sources Used With the 7300 SNM’s

1- 8

40

Figure 1-7. Maximum ENR vs Frequency

1-23. Precision Attenuation. The AILTECH 32 Series Precision Attenuators are tuned, contin
uously variable attenuators which provide an accurate means of measuring Y -factor. These instru
ments are necessary for routine, periodic recalibration of the 7300 System Noise Monitors. How
ever, for critical applications where it is desired to improve precision by recalibrating on-line on a
short term basis, the Precision Attenuator becomes a valuable adjunct to the measurement setup.
These attentuators (see Figure 1-8) are available at common intermediate frequencies in rack mount,
cased, and unmounted configurations.

1- 9

Figure 1-8. AILTECH 32 Precision Attenuator (Cased Version)

1-24. TEST EQUIPMENT

1-25. Table 1-3 lists the test equipment recommended for use in testing, adjusting and servicing

SNM’s.

TABLE 1-3. RECOMMENDED TEST EQUIPMENT

Description

Precision Attenuator

Signal Generator

Digital Multimeter

Vector Voltmeter

Oscilloscope

Noise Generator

Amplifier

1-10

Specification

IF equal to 7 300

Calibrated output from

-100 to -30 dBm at 7300 IF

4V2 digits

10 to 100 MHz

200 MHz 3 dB BW

Compatible with UUT and SNM

Compatible with Noise Generator
and SNM

Recommended Model

AILTECH 32 Series

Boonton 512

Systron-Donner 7004A

PRD 2020

Tektronix 475

AILTECH 76 Series

(Simulates UUT).

CHAPTER II

INSTALLATION

2-1. INTRODUCTION

2-2. This chapter describes unpacking, inspection, preparation for use and initial checkout of

the AILTECH 7300 Series System Noise Monitors.

2-3. UNPACKING, INSPECTION AND DAMAGE CLAIMS

2-4. No special instructions or precautions are necessary for unpacking the SNM; the instrument
is ready for use immediately upon receipt. The following checks should be made to assure that no
damage has occurred during shipment.

a. Inspect the shipping container prior to acceptance from the carrier. Note any damage

to the shipping container on the carrier’s receipt.

b. Inspect the instrument for damage. Check for dents, scratches, broken switches, con

nectors, etc.

c. Remove the top and bottom covers and inspect for broken components or loose

hardware.

d. If damage is not apparent until after the instrument has been accepted, file a claim for

concealed damage with the carrier within 15 days after receipt. All packaging material
must be kept for inspection by the carrier’s agent. A copy of the claim must be for
warded to AILTECH.

2-5. ANCILLARY ITEMS
2-6. Each SNM is accompanied by a mating line cord, a mating plug for the auxiliary output con

nector, and one instruction manual. Before discarding the shipping container, make certain these

items are removed.

2-7. RACK MOUNTING

2-8. Rack Mounting Adapter Kit, Option 11 is required to secure the AILTECH 7320 in a
standard 19 inch rack. The kit consists of two right angle brackets which bolt to the side of the

unit. Complete assembly instructions are provided with the kit.

2-9. PREPARATION FOR USE

2-10. Prior to shipment from the factory, the internal mode switches of the System Noise Monitor
are set for normal automatic noise figure (or temperature) measurements, and the line voltage
switch on the rear panel is set to the value appropriate for the shipping destination. However, it is
good practice to check these settings prior to operating the instrument as follows:

. a. Note the setting of the rear panel line voltage switch. Set it to 115 or 230 volts AC

as required (see Figure 3-1).

2 -1

b. Check both line fuses, F I and F2, and make certain they are the correct value for the

line voltage selected:

230 VAC: FI, F2 = 1/8 Amp.

115 VAC: FI, F2 = 1/4 Amp.

c. Remove the single Phillips-head screw holding the top cover in place, and remove the

top cover.

d. See Figure 3-5 for the location of the IF-Video board and for the locations of the MAN-

AUTO and noise generator ON-OFF switches on the IF-Video board.

e. Make certain that the MAN-AUTO switch is in the AUTO position and the noise

generator ON-OFF switch is in the OFF position.

2-11. INITIAL CHECKOUT

2-12. This operational checkout is a preliminary test and is not intended to validate performance
standards. (For complete Validation Procedure, refer to Chapter V.) Figure 3-1 and Table 3-1
locate and describe the function of the controls, indicators and connectors referenced below.

2-13. The equipment required for initial operational checkout is as follows:

a. Oscilloscope — Tektronix 475 (or equivalent).

b. Signal Generator — Boonton Model 102A (or equivalent).

c. Digital Multimeter — SystonDonner 7004A.

2-14. General

2-15. Perform the procedures detailed under paragraph 2-10. Connect the line cord to the appro
priate AC power source. '

CAUTION

The 7300 System Noise Monitors are low power instruments, but routine

precautions should be observed due to the possibility of contact with the
applied AC line.

2-16. Checkout procedures

a. With the power ON-OFF switch in the OFF position and the instrument in its normal

operating orientation, note the reading of the front panel meter. If it indicates
infinity (°°) proceed to step (b). If it does not indicate infinity, adjust the meter as
follows:

2- 2

1. Locate the zero adjustment screw at the rear of the meter case, between and just
below the terminals.

2. Rotate the screw until the meter reads up-scale (lower noise figures).

3. Continue rotating the screw in the same direction until the needle again indicates
infinity.

b. Set the power ON-OFF switch to the ON position, allow a few minutes for stabiliza

tion, and note that:

1. The red power indicator is illuminated.

2. The green SIGNAL LEVEL indicator is not illuminated.

c. Set the RANGE switch on the front panel to the HIGH position. Note that the meter

still indicates infinity.

d. Connect the output of the signal generator to the IF input. Set the output frequency

to the center frequency of the SNM. Set the output level to rated sensitivity of the
SNM:

-70 dBm for standard units

-100 dBm for units equipped with Option -07, High Sensitivity.

Note that the green SIGNAL LEVEL lamp is illuminated.

e. Locate the MAN-AUTO switch on the IF-Video board and set it to the MAN position.

Note that the green SIGNAL LEVEL lamp extinguishes.

f. Set the front panel RANGE switch to the LOW position. Adjust the signal generator

output level for full-scale indication (0 dB or 60K). Adjust the internal MAN GAIN *
control counterclockwise for a quarter-scale indication (6 dB or 240K).

g. Set the front panel RANGE switch to the HIGH position. Note that the indication

rises to approximately full-scale (± 2 dB).

h. Connect the multimeter, set up to read +28 volts DC, to the BNC connector on the

rear panel marked NOISE SOURCE. Note that the multimeter reads 0 ± 0.5 volts.

i. Set the noise generator ON-OFF^witch on the IF video board to ON. Note that the

multimeter reads +28.00 ±0.05 volts.

j. Disconnect the multimeter. Set the noise generator ON-OFF and MAN-AUTO

switches on the IF-Video board to OFF and AUTO respectively. Connect the oscil
loscope to the NOISE SOURCE BNC connector on the rear panel. Note that the
output is a rectangular, positive pulse, alternating between 0 and +28 volts, at about
a 285 Hz rate).

k. Disconnect the oscilloscope, and replace the top cover.

* These controls are on the front panel of those units equipped with Option 10.

NOTE

If the instrument fails any portion of the checkout procedure, it requires
adjustment or repair. Refer to Chapter V for adjustment and troubleshooting
instructions. If the unit is still under warranty, contact your local AILTECH
representative. .

2- 3 /2 - 4

CHAPTER III

OPERATING INSTRUCTIONS

3-1. GENERAL

3-2. This chapter provides a description of the SNM operating controls, indicators and connectors
and typical SNM operating procedures.

3-3. DESCRIPTION OF OPERATING CONTROLS, INDICATORS AND CONNECTORS.

3-4. The front and rear panel controls, indicators and connectors for SNM Models 7310/7320
are listed in Table 3-1 and illustrated in Figure 3-1. The functions of the controls, indicators and
connectors for Models 7310 and 7320 are identical.

3-5. SET-UP PROCEDURES
3-6. The AILTECH 7300 System Noise Monitors are normally applied to the continuous or peri

odic measurement of a single receiving system, or repeated measurements of similar types o f.
devices (as on a production line test station). Therefore, some care should be exercised in setting
up the measurement system to insure the validity of the indicated results.

3-7. There are three major factors to be considered in setting up the measurement system:

a. Interconnections.

b. Establishment of the correct Excess Noise Ratio (ENR) setting for the front panel

thumbwheel switch on the SNM.

c. Establishment of signal levels within the measurement range of the SNM.

3-8. Interconnections

3-9. In general, there are two types of set-ups for noise parameter measurements. For purposes
of identification these will be referred to as “ bench” and “ operating” noise measurements.

3-10. Most true noise figure measurement are of the bench type. In this case, the setup will be as

indicated in Figure 3-2.

3-11. If the noise source is a typical laboratory noise generator with an excess noise ratio (ENR)
less than 16 dB — such as the AILTECH 7615, 7616, and 7617 Noise Generators — it can be con
nected directly to the input of the unit-under-test (UUT). .

3-12. If the noise source is a high-level unit with an ENR greater than 16 dB — such as most units

in the 7650, 7660 series — a calibrated attenuator sufficient to reduce the ENR to a value between

6 and 15.9 dB must be inserted between the noise source and the input of the UUT (effective ENR

is the noise source ENR less the attenuation in dB).

3-13. Operating measurements are those made with the receiver connected in its normal operating
environment. In most cases, this means the input connected to an antenna. Noise is injected into
the system by means of a directional coupler (see Figure 3-3). This setup usually requires a high
level noise source, such as the AILTECH 7650 or 7660.

3- 1

TABLE 3-1. AILTECH 7310/7320 SYSTEM NOISE MONITORS CONTROLS, INDICATORS

AND CONNECTORS

Key

(Figure 3-1)

1

2

3

4

5

5a

6

7

Reference

Title

ON OFF

SYSTEM ENR (dB)

SIGNAL LEVEL

NOISE FIGURE (dB)

NOISE TEMPERA
TURE—Kelvins

RANGE LOW/HIGH S2

Fuse

Designation

DL1

SI

S3

DL2 Green indicator is illuminated when the

MI Indicates Noise Figure.

MI Alternate meter scale indicates

FI Line fuse.

Function

Red indicator is illuminated when AC
power is applied.

Lever switch controls application of AC
power.

Thumbwheel switch calibrates SNM for
selected excess noise ratio.

input IF level exceeds some arbitrary
minimum.

Operating Noise Temperature.

Rocker switch selects meter range.

10

11

12

13

8

9

Fuse

LINE

AC INPUT

Connector

IF INPUT

NOISE SOURCE J9

F2 Line fuse.

S ll

—.

J1

J8

Slide switch selects primary AC input
line voltage.

Recessed plug for application of
primary AC input.

Multipin connector (Amphenol 57

20240-1, mate supplied) for auxiliary
outputs (see paragraph 1-17).

BNC female connector for application
of IF signal from unit under test.

BNC female connector provides exci
tation for the AILTECH Series 7600
Noise Source.

3-2

11

3-3

RF

NOISE*
GENERATOR

*TYPICAL MODELS - 7615, 7616, 7617

INPUT

]

(a) Set-up for Bench Measurements Using Noise Sources

With ENR’s Between 6.0 and 15.9 dB

DEVICE
UNDER

TEST

IF

OUTPUT

IF

INPUT

(J8-REAR

PANEL)

(J7-REAR

PAN ELI

NOISE
SOURCE

(b) Set-up for Bench Measurements Using High-Level Noise Sources

Figure 3-2. Bench Measurement Set-ups

Figure 3-3. Typical “ Operating” Measurement Set-up

3 -4

3-14. The measurement performed by a setup such as that illustrated in Figure 3-3 is often

called Operating Noise Figure. This is a noise figure measurement in which the cold noise tempera
ture is that of the actual operating termination, but the results are displayed as though the termina
tion was at the standard reference temperature, 290 kelvins. In general, this measurement will yield

lower noise figure readings than a true noise figure measurement (assuming a quality antenna with
an effective noise temperature less than 290K). This type of measurement is quite commonly made
on radar receivers, and is sometimes called radar noise figure.

3-15. If the SNM readout is in noise temperature, then the measured parameter is Operating Noise
Temperature. This parameter is often measured on high-sensitivity, long range receivers, such as
satellite earth stations.

3-16. Other factors to be considered are:

a. Frequency compatibility between the noise source and the RF input of the UUT (a

matter of proper noise source selection).

b. Frequency compatibility between the IF output of the UUT and the System Noise

Monitor. This may require frequency conversion (see paragraph 1-19 for options
which provide this feature).

3-17. Excess Noise Ratio Setting

3-18. The accuracy of the 7300 SNM depends upon accurate setting of the front panel ENR
thumbwheel switch. Any error in this switch setting is translated directly — dB for dB — to the
noise figure indication.

3-19. Laboratory or bench-type noise generators such as the AILTECH 7615, 7616, and 7617 (see
Figure 1-6) have an ENR vs. frequency calibration chart attached or printed on the generator body
and are accompanied by a record of calibration. System noise sources, such as the 7650 and 7660
are also accompanied by calibration records.

3-20. To determine the ENR thumbwheel settings:

a. Locate the two frequencies on the noise source calibration record (or calibration

chart) that straddle the RF input frequency of the UUT (assuming the input frequency
does not coincide with a calibration point).

b. Use straight line interpolation to determine the basic noise source ENR.

c. If the set-up is as shown in Figure 3-2(a), adjust the ENR thumbwheel to the result in

(b) to the nearest 0.1 dB.

d. If the set-up is as shown in Figure 3-2(b), subtract the attenuation (in dB) from the

ENR determined in (b). Adjust the ENR thumbwheel to the resulting difference to
the nearest 0.1 dB.

3-21. Establishing the Correct Signal Levels

3-22. The basic sensitivity (low point of the valid signal level range) of the 7300 System Noise
Monitors is better than -7 0 dBm. This is not the point at which the green Signal Level light comes
on. This light is meant only as a gross indication that some signal is available from the UUT.

3-5

3-23. To determine sensitivity or low end of the signal level range a signal generator to provide
low level signals at the SNM center frequency is required (a typical unit is the Boonton 102A).

a. Make certain the SNM is in the AUTO mode (S101).

b. Connect a signal generator tuned to the center frequency of the SNM to the IF Input.

c. Gradually increase the signal generator output level from about -85 dBm until the

green Signal Level light illuminates. Note the generator output level.

d. Increase the generator output 5 dB above the point where the Signal Level light comes

on. This is the sensitivity or lower end of the valid signal level range. Note that this

level is less than -70 dBm, and record it for future reference.

NOTE

If a continuous indication of signal level is desired, see Paragraph 3-33.

3-24. The upper end of the valid signal level range will be 40 dB above the sensitivity as deter
mined from paragraph 3-23 (d). All signals — both with the noise source on and the noise source
off — must remain within this range. Figure 3-4 illustrates this range using typical levels.

UPPER L IM IT -3 3 dBm*

LU'
>

LU

_ l

_l

<

z

C/3

-40 dBm —

-50 dBm —

-60 dBm

-70 dBm

-80 dBm

Y

FACTOR

SENSITIVITY -73 dBm*

SIGNAL LEVEL LIGHT -78 dBm*

*Typical Values

3- 6

Figure 34. Illustration of Sensitivity and Signal Level Range

3-25. To insure that the UUT output is within the valid range, proceed as follows:

a. Remove the top cover of the SNM and locate the following controls on the IF-Video

board (see Figure 3-5). These controls are on the front panel of those units equipped

with Option 10, Manual Front Panel Controls:

MAN-AUTO switch, S101

MANUAL GAIN control, R140

Noise Generator ON-OFF Switch, S102 .

b. Connect a signal generator tuned to the SNM center frequency and set the output level

as described in paragraph 3-23 (d).

c. Set the following controls as indicated:

1. Front panel RANGE switch to LOW

2. MAN-AUTO switch S101 to MAN

3. Noise Generator switch S102 to OFF

d. Adjust manual GAIN control, R140, for a convenient on-scale reading at the upper

50% of the scale. Record the setting.

e. Without disturbing the preceding settings, disconnect the signal generator and set up

the measurement system in accordance with Figure 3-2 or 3-3 as required.

f. If the noise figure indication with the control settings as above is higher (down-scale)

than (d), additional gain is required between the UUT and the SNM input. Add gain
as required (or see paragraph 1-19 for an option to provide better sensitivity) to bring
the reading lower in noise figure or temperature than (d) and proceed to (h).

. g. If the indication is a lower noise figure than (d), or off-scale to the right, set Noise

Generator switch S I02 to ON.

h. Add attenuation at the SNM input until the indication returns to (d). If the total

attenuation required is greater than 40 dB, there is too much gain in the UUT, and
fixed attenuation must be provided at the SNM input as part of the set-up.

3-26. After establishing the correct input levels, set MAN-AUTO switch S101 to AUTO and Noise

generator switch S102 to OFF. Replace the top cover.

3-27. OPERATION

3-28. Once set-up is accomplished, the ENR switch correctly set, and the correct signal levels
established, the System Noise Monitor will automatically indicate noise figure or noise temperature.
No further operator activity is required other than setting the RANGE switch for optimum resolu
tion as noted below.

3-29. The AILTECH 7310 and 7320 Analog System Noise Monitors have two noise figure ranges
with 0 and 6 dB at full scale. Increasing noise figure causes the meter to read down-scale. If the
UUT noise figure is less than 6 dB, set the front panel RANGE switch to the LOW position and
read noise figure. If the noise figure is greater than 6 dB set the switch to the HIGH position and
read the noise figure.

5101

MAN-AUTO

SWITCH

5102

MANUAL

ON-ÓFF
SWITCH

O' Uif

1 = 3 0 1 = 1

POWER SUPPLY

PC BOARD ASSEMBLY

298021-1

IF-VIDEO PC

BOARD ASSEMBLY

298020

-1 10 TO 40 MHz

-2 40 TO 70 MHz

3- 8

R140

MANUAL

GAIN

m&\p

ENR PC BOARD

ASSEMBLY

298172

S3

ENR SWITCH

Figure 3-5. Location of the Manual-Auto Controls