HP 5305 B Service manual

O P E R A T I N G A N D S E R V I C E M A N U A L
5305 B
1300 MHz COUNTER

CERTIFICATION
Hewlett-Packard Company certifies that this instrument met its published specifications a
t
the time of shipment from the factory. Hewlett-Packard Company further certifies that its
calibration measurements are traceable to the United States National Bureau of Standards,
to the extent allowed by the Bureau's calibration facility, and to the calibration facilities of
other International Standards Organization members.
WARRANTY AND ASSISTANCE
This Hewlett-Packard product is warranted against defects in materials and workmanship for
a period of one year from the date of shipment. Hewlett-Packard will, at its option, repair or
replace products which prove to be defective during the warranty period provided they are
returned to Hewlett-Packard, and provided the preventive maintenance procedures in this
manual are followed. Repairs necessitated by misuse of the product are not covered by this
warranty. NO OTHER WARRANTIES ARE EXPRESSED OR IMPLIED, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE. HEWLETT-PACKARD IS NOT LIABLE FOR CONSEQUENTIAL
DAMAGES.
Service contracts or customer assistance agreements are available for Hewlett-Packard
products.
For any assistance, contact your nearest Hewlett-Packard Sales and Service Office.
Addresses are provided at the back of this manual.

SECTION I XE
1300 MHz COUNTER
5305 B
This section applies directly to Model 5305B 1300 MHz
Counters having Serial Prefix 1616A. This section is
provided in loose-leaf form for incorporation into the 5300
Measurement System Manual. 5305A instruments are
documented in a separate manual.
This section with enclosed "Manual Changes" sheet
applies directly to HP Model 5305B 1300 MHz Counters
havin
g
Serial Prefix numbers above 1616A.
Subsection VII of this document contains information
p
ertinent to all older instruments.
SERIAL PREFIX: 1616A
NEWER INSTRUMENTS
OLDER INSTRUMENTS
Printed: AUG 1976
Copyright HEWLETT-PACKARD COMPANY 1976
5301 STEVENS CREEK BLVD., SANTA CLARA, CALIF. 95050
MANUAL PART NO. 05305-90008
MICROFICHE PART NO. 05305-90009 PRINTED IN U.S.A.
OPERATING AND SERVICE MANUAL
Model 5305B
Table of Contents

Section
Subsection
Model 5305B
Table of Contents
TABLE OF CONTENTS
Pa
g
e
iii
I X E 5305B 1300 MHz Counter
I GENERAL INFORMATION ...................................................................................... 9E-1-1
9E-1-1. Scope of Manual.................................................................................... 9E-1-1
9E-1-3. Description ............................................................................................ 9E-1-1
9E-1-6. Instrument Identification ....................................................................... 9E-1-2
9E-1-8. Equipment Supplied .............................................................................. 9E-1-2
9E-1-10. Accessories Available ........................................................................... 9E-1-2
9E-1-12. 5300A/5300B Compatibility. ... ............................................................ 9E-1-2
9E-1-14. Specifications ........................................................................................ 9E-1-2
9E-1-16. Recommended Test Equipment............................................................. 9E-1-2
II INSTALLATION......................................................................................................... 9E-2-1
9E-2-1. Unpacking and Inspection ..................................................................... 9E-2-1
9E-2-3. Storage and Shipment............................................................................ 9E-2-1
9E-2-6. Installation and Removal of Plug-On .................................................... 9E-2-1
9E-2-8. Portable Operation................................................................................. 9E-2-1
III OPERATION
9E-3-1
9E-3-1. Introduction ........................................................................................... 9E-3-1
9E-3-3. Operating Characteristics ...................................................................... 9E-3-1
9E-3-5. Input Channels.................................................................................... 9E-3-1
9E-3-9. Resolution.............................................................................................. 9E-3-1
9E-3-11. 1300 MHz Channel Input Levels........................................................ 9E-3-2
IV THEORY OF OPERATION ........................................................................................ 9E-4-1
9E-4-1. Introduction ........................................................................................... 9E-4-1
9E-4-3. A1 LogicBoard ...................................................................................... 9E-4-1
9E-4-5. High Impedance Amplifier ................................................................. 9E-4-1
9E-4-12. Counting Circuits................................................................................ 9E-4-1
9E-4-16. Frequency Multiplier .......................................................................... 9E-4-2
9E-4-30. 1300 MHz ÷ Circuit............................................................................ 9E-4-4
9E-4-32. A2 1300 MHz Amplifier Assembly……………………………………9E-4-4
V MAINTENANCE......................................................................................................... 9E-5-1
9E-5-1. Introduction ........................................................................................... 9E-5-1
9E-5-3. Recommended Test Equipment............................................................. 9E-5-1
9E-5-5. In-Cabinet Performance Check ............................................................. 9E-5-1
9E-5-7. Instrument Access ................................................................................. 9E-5-1
9E-5-9. Periodic Maintenance ............................................................................ 9E-5-1
9E-5-11. Maintenance and Repair ........................................................................ 9E-5-1
9E-5-15. Adjustments........................................................................................... 9E-5-5
9E-5-17. Channel A Adjustments......................................................................... 9E-5-5
9E-5-19. Channel B Adjustments......................................................................... 9E-5-6
9E-5-21. Troubleshooting..................................................................................... 9E-5-6
9E-5-25. 100 MHz Channel Troubleshooting ...................................................... 9E-5-6
9E-5-27. 1300 MHz Channel Troubleshooting .................................................... 9E-5-7
9E-5-29. Both Channels Inoperative…………………………………………...9E-5-7
9E-5-34. Frequency Multiplier .......................................................................... 9E-5-7
VI REPLACEABLE PARTS ............................................................................................ 9E-6-1
9E-6-1. Introduction ........................................................................................... 9E-6-1
9E-6-3. Orderin
g
Information............................................................................. 9E-6-1

i
v
Model 5305B
Table of Contents
List of Tables and Fi
g
ures
TABLE OF CONTENTS (Cont'd)
Subsection Page
VII MANUAL CHANGES .…….....................................................................................9E-7-1
9E-7-1. ManualChanges ...................................................................................9E-7-1
9E-7-3. NewerInstruments................................................................................9E-7-1
VIII CIRCUIT DIAGRAMS..............................................................................................9E-8-1
9E-8-1. Introduction..........................................................................................9E-8-1
LIST OF TABLES
Table Page
9E-1-1. Specifications .............................................................................................................9E-1-3
9E-1-2. Recommended Test Equipment..................................................................................9E-1-4
9E-3-1. Resolution vs GateTime .............................................................................................9E-3-1
9E-5-1. In-Cabinet Performance Check ..................................................................................9E-5-3
9E-5-2. Erroneous Displays Caused by U4 .............................................................................9E-5-7
9E-6-1. Replaceable Parts .......................................................................................................9E-6-3
9E-6-2. Manufacturers Code List ............................................................................................9E-6-8
9E-8-1. Counter Signal List.....................................................................................................9E-8-1
LIST OF FIGURES
figure Page
9E-3-1. dBm-to-Voltage Conversions.....................................................................................9E-3-1
9E-3-2. Front Panel Controls, Connectors, and Indicators ......................................................9E-3-2
9E-3-3. Self-Check Measurements..........................................................................................9E-3-3
9E-3-4. 100 MHz Channel Frequency Measurements……………………………………….9E-3-4
9E-3-5. 90 MHz-1300 MHz Channel Frequency Measurements ............................................9E-3-5
9E-4-1. Phase Detector Block Diagram...................................................................................9E-4-2
9E-4-2. VCO Waveforms at about 2MHz ...............................................................................9E-4-3
9E-4-3. VCO Characteristics...................................................................................................9E-4-4
9E-5-1. Separation Procedure..................................................................................................9E-5-2
9E-5-2. Test Setup for 1300MHz Adjustment.........................................................................9E-5-5
9E-6-1. Details of Input Connector J1 and Fuse Mounting………………………………….9E-6-8
9E-8-1. Channel B and Frequency Multiplier Circuits, Schematic Diagram ..........................9E-8-5
9E-8-2. Channel A and Lo
g
ic Board Circuits, Schematic Dia
g
ram………………………….9E-8-9

9E-1-1. SCOPE OF MANUAL
9E-1-2. This manual provides operating and service
information for the Hewlett-Packard Model 5305B 1300
MHz Counter. Information for the mainframes (5300A
or 5300B) is contained in separate manuals. This
manual is divided into eight sections containing the
following information:
SECTION 1 GENERAL INFORMATION covers a
description of the counter, equipment supplied,
accessories, specifications, and recommended test
equipment.
SECTION II INSTALLATION provides instruc-
tions for unpacking, inspection, preparation for use,
shipment, and storage for the counter.
SECTION III OPERATION covers the counter's
operating features including front-panel controls,
input level considerations, and operating and self-
check procedures.
SECTION IV THEORY OF OPERATION
describes the counter's theory of operation.
SECTION V MAINTENANCE contains an in-
cabinet performance check, adjustments, and
troubleshootin
g
information.
SECTION VI REPLACEABLE PARTS provides a
complete list of the counter's replaceable parts and
information for ordering parts.
SECTION VII MANUAL CHANGES provides
information necessary to backdate the manual to cover
earlier instruments.
SECTION VIII SCHEMATIC DIAGRAMS THEORY
contains schematic diagrams, and component locators.
9E-1-3. DESCRIPTION
9E-1-4. The 5305B extends the frequency measuring
capability of the 5300 Measuring System to the UHF range.
The counter features burst or CW measurements to 1300 MHz,
separate channels to cover 90 MHz-1300 MHz and 50 Hz to
100 MHz both with 20 mV rms sensitivity, high resolution
mode for fast tone measurements, automatic gain control for
both channels or manual attenuator control for the high
frequency channel, fuse protected high frequency channel,
and probe power plus accessory preamp for high sensitivity
applications. When operating in the high resolution mode, a
phaselocked multiplier gives 1000 times improvement in the
resolution of audio tone measurements. This feature is
especially useful for servicing equipment using tone
modulation for di
g
ital encodin
g
on the carrier.
9E-1-1
Model 5305B
General Information
SECTION I XE
5305B 1300 MHz COUNTER
SUBSECTION I
GENERAL INFORMATION

Model 5305B General
Information
The 5305B is applicable to mobile communication bands
in addition to VHF and UHF TV transmissions plus
TACAN/DME and ATC radar transponders.
9E-1-5. The 10855A Preamplifier is available to boost
the UHF sensitivit
y
of the counter b
y
a minimum of 22 dB.
9E-1-6. INSTRUMENT IDENTIFICATION
9E-1-7. Hewlett-Packard instruments have a 2-section,
10-character serial number (0000A00000) which is located
on the rear panel. The 4-digit serial prefix identifies
instrument changes. If the serial prefix of your instrument
differs from that listed on the title page of this manual,
there are differences between this manual and your
instrument. Instruments having higher serial prefixes are
covered with a "Manual Changes" sheet included with this
manual. If the change sheet is missing, contact the nearest
Hewlett-Packard Sales and Service Office listed at the
back of this manual. Instruments having a lower serial
prefix than that listed on the title page, are covered in the
backdating Section VII.
9E-1-8. EQUIPMENT SUPPLIED
9E-1-9. The 5305B is supplied with an operating and
service manual.
9E-1-2
9E-1-10. ACCESSORIES AVAILABLE
9E-1-11. For high-sensitivity UHF applications, the
10855A Preamplifier can be used with the 5305B. The
10855A covers the 2 MHz to 1.3 GHz range with a gain of
22 dB minimum. Power requirements are +15 volts at ≈40
mA. The 5305B has a front-panel connector to supply the
required + 15 volts to 10855A.
9E-1-12. 5300A/5300B COMPATIBILITY
9E-1-13. The 5305B is fully compatible with either the
5300A or the 5300B mainframe. Unlike the 5305A, a high-
stability time base is not available for the 5305B, however
a hi
g
h-stabilit
y
time base is available for the 5300B.
9E-1-14. SPECIFICATIONS
9E-1-15. Specifications are listed in Table 9E-1-1.
9E-1-16. RECOMMENDED TEST EQUIPMENT
9E-1-17. Test equipment recommended for testing,
calibration, and repair of the 5305B is listed in Table 1-2.

Model
5305B General
INPUT CHANNEL A (CW OR BURST)
Table 9E-1-1. Specifications
FREQUENCY MEASUREMENT
Range: 90 MHz to 1300 MHz, prescaled by 16
Sensitivity: 20 mV rms
Impedance: 50Ω
Attenuator: Continuously variable to give optimum
noise suppression for si
g
nals up to 3.5V rms.
Overload Protection: 5V rms, maximum. Input cir-
cuitry is fuse protected; fuse is located in BNC
connector and is accessible from the front panel.
Operating Dynamic Range: > 47 dB
INPUT CHANNEL B (NORMAL AND HIGH
RESOLUTION MODE)
Range: 50 Hz to 100 MHz, direct count in normal
mode. 50 Hz to 10 kHz in high resolution mode. In
the high resolution mode, the 5305B uses a phase-
locked multiplier to increase resolution X1000 over
normal measurement resolution.
Sensitivity: 20 mV rms
Impedance: 1 MΩshunted by less than 40 pF.
Overload Protection: 250V rms from 50 Hz to 10
kHz, declining to 10V rms above 10 MHz.
Search Indicator: In high-resolution mode the "S"
annunciator is lit whenever the input is beyond the
proper frequency range, or too weak to measure, or
during the brief acquisition time following signal
interruption.
Automatic Hold: In high-resolution mode, the last
valid reading is held in display when input is
terminated.
RESOLUTION (SELECTABLE):
Normal Mode (50 Hz to 1300 MHz): 0.1 Hz to
10000 Hz in decade steps corresponding to gate times
of 10 sec to 0.0001 sec in decade steps on channel B
and to gate times of 160 s to .0016 s in decade steps on
channel A.
High Resolution Mode (50 Hz to 10 kHz): 0.0001,
0.001, 0.01, 0.1, 1, 10 Hz corresponding to 10, 1, 0.1,
0.01, 0.001, 0.0001 second
g
ate times on channel B.
Accuracy: ±1 digit displayed ± time base accuracy.
Display: Hz, kHz, MHz with positioned decimal point.
GENERAL
Check: Counts internal 10 MHz reference frequency
to check counting circuits.
Operating Temperature: 0° to 50°C.
Power Requirements: Nominally 12 watts including
mainframe.
Weight: Net 1.0 kg (2-1/4 lbs.); Shipping 1.8 kg (4 lbs.)
Dimensions: With mainframe, 89 mm H (3-1/2")x 160
mm W (6-1/4") x 248 mm L (9-3/4").
Compatible Mainframes: 5300A (6 digits) or 5300B
(8 digits). 5300B is recommended.
Accessories: 10855A Preamp (22 dB gain).
9E-1-3

Model 5305B General
Information
Table 9E-1-2. Recommended Test Equipment
Instrument Required Characteristics Recommended Type
Oscilloscope 50 MHz Bandwidth HP 180A
Vertical Plug-In 50 mV/div Sensitivity HP 1801A
Time Base Plug-In 50 MHz Bandwidth HP 1821A
Sampling Plug-In 1000 MHz HP 1810A
Optical Sampling Plug-In If desired to measure up to 1300 MHz HP 1811A/1432A
Synthesized Signal Generator 1300 MHz HP 8660B/86602A
Power Meter -30 dBm to + 10 dBm HP 435A
Power Sensor 90 MHz to 1300 MHz HP 8481A
Test Oscillator 50 Hz to 10 MHz 3V rms HP 651B
Mainframe HP 5300B
Digital Voltmeter -5V to +20 V dc HP 5306A
Power Splitter 50 ohms 90 MHz to 1300 MHz HP 11667A
Scope Probe 10:1 1 MegΩHP 10004D
9E-1-4

Model 5305B
Installation
SECTION IX E
5305B 1300 MHz COUNTER
SUBSECTION II
INSTALLATION
9E-2-1. UNPACKING AND INSPECTION top and bottom molded frame of polystyrene (HP Part No.
9220-1545). Also included with the instrument is a plastic
dust-protection cover (HP Part No. 9220-1762).
9E-2-5. ENVIRONMENT. Conditions during storage
and shipment should be normall
y
limited as follows:
a. Maximum altitude: 25,000 ft.
b. Minimum temperature: -40°F( -40°C).
c. Maximum temperature: +167°F(+75°C).
9E-2-2. If the shipping carton is damaged, ask that the
carrier's agent be present when the instrument is unpacked.
Inspect the instruments for damage, such as scratches,
dents, broken knobs, etc. If the instrument is damaged or
fails to meet performance tests when used with the 5300B
Measuring System, notify the carrier and the nearest
Hewlett-Packard Sales and Service Office immediately.
Performance check procedures are located in Section IX E-
5, and Sales and Service Offices are listed in Section VI of
the 5300B portion of the manual. Retain the shipping
carton and the padding material for the carrier's inspection.
The Sales and Service Office will arrange for the repair or
replacement of the instrument without waiting for the
claim a
g
ainst the carrier to be settled.
9E-2-3. STORAGE AND SHIPMENT
9E-2-4. PACKAGING. To protect valuable electronic
equipment during storage and shipment, always use the
best packaging methods available. Your Hewlett-
Packard Sales and Service Office can provide packaging
material, such as that used for original factory packaging.
Contract packaging companies in many cities can provide
dependable custom packaging on short notice. Here is one
recommended packa
g
in
g
method:
a. The original container is a corrugated cardboard
box with 200 lbs. burst test (HP Part No. 9211-1620). The
instrument is secured and protected, while in the box, by a
9E-2-7. The 5305B 1300 MHz Counter must be used
with a mating 5300A or B Measuring System, before any
measurements can be made. To mate the 5305B 1300 MHz
Counter with a 5300 Measuring System, see Figure 2-1
and Para
g
raph 2-11 in the 5300 portion of the manual.
9E-2-8 PORTABLE OPERATION.
9E-2-9. The use of the HP Model 5310A Battery Pac
k
enables the 5300 Measuring System and 5305B 1300 MHz
Counter to be used in areas removed from ac power
sources. The 5310A Battery Pack typically provides 5
hours of portable operating time before recharging. Tables
1-2 and 1-4 in 5300 portion of the manual lists the HP
5310A Battery Pack as an available accessory.
Documentation on the 5310A is also included in Section
IV through VIII of the 5300 portion of the manual. To
prepare the 5300/5305B for portable operation, refer to
Paragraph 2-13 and Figure 2-2 in the 5300 portion of the
manual.
9E-2-1
9E-2-6. INSTALLATION AND REMOVAL OF
PLUG-ON

Model 5305B
Operation
SECTION IX E
5305B 1300 MHz COUNTER
SUBSECTION III
OPERATION
9E-3-8. The frequency range of Channel B depends on the
mode of operation - normal or high resolution. In the
normal mode, Channel B covers 50 Hz to 100 MHz. With
high-resolution selected, Channel B covers 50 Hz to 10
kHz. The high resolution mode uses a phase-locked
multiplier to increase resolution by a factor of 1000. Input
impedance is 1 Megohm shunted by less than 40 pF. A 10
to 1 divider probe can be used to increase the input
impedance to 10 Me
g
ohms.
9E-3-1. INTRODUCTION
9E-3-2. This section covers operating information for the
5305B including a description of controls, indicators, and
connectors, resolution, input levels, and operating
p
rocedures for frequenc
y
measurements and self check.
9E-3-3. OPERATING CHARACTERISTICS
9E-3-9. RESOLUTION
9E-3-4. The 5305B Counter performs frequency mea-
surements by means of two separate input channels. These
channels provide a combination of low frequency
measurements and high-sensitivity, high frequency
measurements. Measurement capability is applicable to all
frequencies in the VHF and mobile communication bands in
addition to a significant portion of the UHF band. The
10855A Preamplifier can be used to boost the UHF inpu
t
sensitivit
y
b
y
22 dB.
9E-3-10. The 5305B has a RESOLUTION switch which
determines the least-significant digit (LSD) dis
p
layed. Fo
r
example, with an input of 123,456 Hz, setting the
RESOLUTION switch to 1 kHz places the "3" in the LSD.
Setting the switch to 10 Hz, places the "5" in the LSD.
Resolution can be expressed in terms of the counter's gate
time, as shown in Table 9E-3-1.
9E-3-5. Input channels Table 9E-3-1. Resolution vs Gate time
Figure 9E-3-1. dBm-to-Voltage Conversions
9E-3-6. Two input channels are provided, Channel A - 90
MHz to 1300 MHz and Channel B - 50 Hz to 100 MHz.
Both channels have 20 mV rms sensitivit
y
.
9E-3-7. Channel A prescales the input frequency by 16 and
can be used to measure CW or burst signals. Input coupling
is ac. An AGC circuit is included to give a dynamic range
of >47 dB. An internal fuse, located inside the input jack,
p
rotects circuitry from overloads greater than 5V rms. Note
that a blown fuse may not prevent the counter from
measuring high-frequency inputs. In this instance, the
counter’s circuitry is no longer protected,ie.,as it would be
at lower frequencies by a good open circuit. If the fuse
blows, a replacement fuse is supplied with the instrument.
RESOLUTION GATE TIME
80 MHz 1100 MHz
.1 Hz 10 s 160 s
1 Hz 1 s 16 s
10 Hz .1 s 1.6 s
100Hz .01s .16s
1 kHz 1 ms 16 ms
10 kHz .1 ms 1.6 ms
9E-3-1

Model 5305B
Operation
9E-3-11. 1300 MHz Channel Input Levels voltage, power, and dBm. This scale applies to a 50-ohm
system and is not applicable to the 100 MHz channel. The
shaded area represents the specified operating range of the
1300 MHz channel.
9E-3-12. The 1300 MHz channel is a 50-ohm system with a
maximum input of 5V rms. Figure 9E-3-1 provides a
conversion scale for determinin
g
respective levels of
Figure 9E-3-2. Front Panel Controls, Connectors, and Indicators
N
OTE
The "S" annunciator on the 5300 lights during the high-resolution mode wheneve
r
the input is beyond the proper frequency range, or too weak to measure, or during
ac
q
uisition followin
g
si
g
nal interru
p
tion.
1. 90 MHz - 1300 MHz Input Jack. With RANGE
switch set to A, accepts input frequencies from 90
MHz to 1300 MHz. Input sensitivity is 20mV. 50
ohm input impedance and ac coupled. Maximu
m
input is 5V rms. Fuse is located inside jack. Use
a
BNC connector as a wrench to remove and tighten
the fuse jack. Replacement HP part number for fuse
is 2110-0301.
accepts input frequencies from 50 Hz to 100 MHz.
With RANGE set to B HIGH RESOLUTION,
accepts frequencies up to 10 kHz. Input sensitivity
is 20 mV rms. Input impedance is 1 Megohm
shunted b
y
less than 40 pF. Channel is ac coupled.
5. RANGE switch. Allows selection of either of the
two input channels or the self-check mode. In the
CHK position, allows system to count the internal
10 MHz clock signal. Measurement is not affecte
d
by
si
g
nals connected to the input
j
acks.
2. ATTENUATOR Control. Provides manual control
of input attenuator circuit for 1300 MHz channel.
MIN position provides minimum signal attenuation.
MAX position provides maximum attenuation.
AGC circuit
g
ives >47 dB d
y
namic ran
g
e. 6. RESOLUTION Switch. The counter's leas
t
-
significant digit displays the measured resolution o
f
the input signal that is selected with the switch. Fo
r
example, 10 Hz selected with 6,789 Hz inpu
t
frequenc
y
: counter displa
y
s 6.78 kHz.
3. PREAMP POWER. Supplies + 15V @ ≈40 mA to
p
ower 10855A Preamplifier.
4. 100 MHz Input Jack. When RANGE is set to B,
9E-3-2

Model 5305B
Operation
Figure 9E-3-3. Self-Check Measurements
●Indicates overflow light is on.
9E-3-3
5300A Self Check 5300B Self Check
Resolution
Selector Display Annunciator Display Annunciator
10 kHz 0010.00 M, Hz 000010.00±1M,Hz
1 kHz 010.000 M, Hz 00010.000±1M,Hz
100 Hz 10.0000 M, Hz, C 0010.0000±1M,Hz,C
10 Hz 0.00000 M, Hz, C 010.00000±1M,Hz,C
1 Hz ●000.000 K, Hz, C 10000.000±1K,Hz,C
.1 Hz ●00.0000 K, Hz, C 0000.0000±1K,Hz,C
1. Apply input power to 5300 ac receptacle.
2. Turn counter on with 5300 SAMPLE RATE control.
Adjust SAMPLE RATE for minimum display time
(full ccw).
3. Set RANGE switch to CHK position. Display is a
function of RESOLUTION switch.

Model 5305B
Operation
Figure 9E-3-4. 100 MHz Channel Frequency Measurements
1. Apply power to 5300 ac receptacle.
2. Turn counter on with 5300 SAMPLE RATE control.
3. Set RANGE switch to B position.
4. Connect input signal to 100 MHz jack.
5. Set RESOLUTION switch for number of digits desired
in display.
6. Adjust SAMPLE RATE control for convenient interval
between measurements.
7. For high resolution, set RANGE switch to B 10 kHz
MAX - HIGH RESOLUTION X1000. This limits the
input frequency to 10 kHz but gives resolution up to 4
decimal places.
9E-3-4

Model 5305B
Operation
Figure 9E-3-5. 90 MHz -1300 MHz Channel Frequency Measurements
1. Apply input power to ac receptacle.
2. Turn counter on with 5300 SAMPLE RATE control.
3. Set RANGE switch to A position.
4. Set RESOLUTION switch to 10K.
5. Set ATTENUATOR control to MIN position.
CAUTION
Input level must not exceed 5V rms.
6. Connect input signal to 90 MHz -1300 MHz jack.
7. Adjust ATTENUATOR control until counter
stops displaying, then back again until counter
gives a stable display of the proper frequency.
9E-3-5

Model 5305B
Theor
y
of Operation
9E-4-12. Countin
g
Circuits
SECTION IX E
5305B 1300 MHz COUNTER
SUBSECTION IV
THEORY OF OPERATION
9E-4-1 INTRODUCTION.
9E-4-2. The 5305B consists of two assemblies, Logic
Board A1 and 1300 MHz amplifier A2. Two input chan-
nels for frequency measurements are provided, Channel A
accepts signals from 90 MHz to 1300 MHz and Channel B
is used for signal inputs up to 100 MHz. Channel B signals
are connected directly to the A1 Logic Board. Channel A
signal inputs are routed to the 1300 MHz Amplifier A2.
The followin
g
theor
y
describes the two assemblies.
9E-4-3. A1 LOGIC BOARD
9E-4-4. A1 consists of the following major circuits;
High-Impedance Amplifier, Counting, Frequency
Multiplier, and 1300 MHz. Paragraphs 9E-4-5 through
9E-4-30 describe the theor
y
of operation for these circuits.
9E-4-3 High Impedance Amplifier
9E-4-6. The high-impedance amplifier consists o
f
three main stages: (1) An input buffer (Q1, Q2) that
provides high input impedance at unity gain. (2) An AGC
(automatic gain control) amplifier (U6B and C) to generate
the required gain to maintain a relatively constant output
with a wide range of inputs. This assures that the counter
will read the proper frequency in the presence of noisy
input signals. (3) A Schmitttrigger U6A and driver U16 to
convert noisy, slowchanging signals to "clean" square
waves with fast rise times to drive the countin
g
circuits.
9E-4-7. INPUT CIRCUIT OPERATION. The signal
enters the amplifier through dc blocking capacitor C4,
which, along with C7, R10, R7, CR4, and CR2, protects
against large ac peaks at low frequencies. At high
frequencies, R7 and CR4 and CR2 provide the input
protection for the unity-gain boot-strapped sourcefollower
circuit Q1 and Q2.
9E-4-8. AGC OPERATION. For small signal levels
(below ≈10 mV rms), the output of U8 pin 1 is <.6V (with
no input signal, the voltage is about -3.5V). This causes
Q5 and Q4 to turn off which results in Q3 turnin
g
on.
The low source-to-drain impedance (50Ω) shunts resistor
R12. The signal passes unattenuated through Q3 to amplifier
U6C. The output at U6B(6) feeds the signal through R33 and
C25. The signal is converted to dc by CR9, C24 and R35. As
the input signal level increases, the AGC voltage at U8(1)
increases above .6 volts to a maximum of ≈+2 volts. Both
CR5 and CR7 begin to conduct and their resistance drops
rapidly to a few ohms, shunting most of the signal to ground.
At the same time, Q5 begins to conduct and causes Q4 to
conduct.
9E-4-9. When Q4 is full on, it generates more than -5 volts
gate-to-source voltage on Q3. This tends to "pinch off" Q3,
thereby raising its resistance. With R6 as the main signal
path, only a small portion (10 to 20 mV p-p) of a large input
signal (10V p-p) drives amplifier U6C. This prevents
saturation of U6, and prevents the degradation in signal-to-
noise ratio that saturation would cause. Thus Schmitt trigger
U6A is triggered only by the largest signal at the input and
not noise.
9E-4-10. DC FEEDBACK AND DUTY CYCLE CON-
TROL. The first two amplifier stages of U6 have a fixed
voltage gain of typically 30 to 40 with a bandwidth of 100
MHz. U8 monitors the output of U6B and regulates the dc
level at about 1.3V, regardless of temperature and device
differences.
9E-4-11. SCHMITT TRIGGER AND OUTPUT. The
third stage of U6 is used as a Schmitt trigger.This circuit
shapes the .6V p-p sine wave at its input into a .8V p-p
square wave. It will respond to signals less than 0.3V p-p in
amplitude and thus rejects noise on the input signal. U16
amplifies the square wave and converts it to TTL levels to
drive U22.
9E-4-13. The following paragraphs describe the counting
circuits that are common to all input modes. The RANGE
switch enables one of four NOR gates to pass its respective
signal to the Main Gate U13A and to the arm flip-flop,
U17B. The signals are (1) Channel A divided by 16, U12C;
(2) Channel B, U12A; (3) Channel B times 1000(PLO),
U12B; and (4) 10 MHz clock (check), U13B.
9E-4-1

Model 5305B
Theor
y
of Operation
9E-4-14. In the Channel B mode, for example, the
operation is as follows. Once the sample rate runs down
and the INHIBIT line returns high, the next signal pulse
from U12A sets U17B. The High output from U16D(13)
arms the counter by allowing the CLOSE line to go
High. The arm signal also passes the 10 MHz clock
signal to the mainframe through U10A and U10B. The
mainframe responds by clocking U17A with a LOG 0
pulse, which sets the Q output Low and opens the Main
Gate. The signal now passes to the decade counter, U14,
where it is divided by 10. The data output of U14 feeds
U13C, which provides a 60/40 duty cycle of the divided
signal to level translators Q9 and Q10. The signal then
enters the main frame's countin
g
assembl
y
on the F1 line.
N
OTE
U6, 12. 13, 14, 17, and 25 are ECL devices
that are connected to the +5V supply. They set
the logic states to ≈4.3V for a High and ≈
3.2V for a Low.
9E-4-15. The measurement ends when the count in the
mainframe's Time Base decade reaches its capacity.
The decade then outputs a TB OUT pulse. The LOG
pulse immediately following sets the MGFF and
disables the Main Gate, U13A. During the mea-
surement, the three-state data latch, U5, does not accept
any new input data. Its output, however, is enabled
periodically by the Low pulse from U4(15). Because of
the counting decade in the 5305B, U4 alters the Digital
Address codes so the digits are correctly placed in the
display. Therefore, the Σ4 output goes Low for one
count out of eight and switches the latch from its high
impedance state to the low impedance (active) state.
This occurs for each scan of the display. When the
measurement ends, the XFER line enables U4 and new data
enters the latch with the next clock pulse from U11(4).
9E-4-17. The Frequency Multiplier circuit contains a PLO
(Phase-Locked Oscillator) that is used when the RANGE
switch is set to the B 10 kHz MAX position. The PLO
multiplies the Channel B input frequency by 1000. which
means the display's count will be 1000 times higher than
normal. Thus, for a 51.234 Hz input and a 1 sec gate time,
the counter's display would be 00.051 kHz without the PLO
and 51.234 Hz with the PLO. The readout is corrected by
changing the annunciator from MHz to kHz or kHz to Hz.
The phase detector block diagram is shown in Figure 9E-
4-1.
9E-4-18. PHASE DETECTOR. The signal to be mea-
sured passes through the channel B amplifier and is applied
to pin 1 of U22, a phase/frequency detector. The other input
to U22 is the voltage-controlled oscillator's signal, which
has been divided by 1000 in U19, 20, and 21. U22 is a TTL
device with negative edge-triggered inputs and active low
outputs. Under normal, phase-locked operation, the negative
edges at the inputs occur at the same moment, and the two
outputs are hi
g
h.
9E-4-19. Under these conditions, the two diodes following
the detector (also part of U22) are back-biased and pass no
current. Thus, no current enters the integrator amplifier,
U23, and its output volta
g
e remains fixed.
Figure 9E-4-1. Phase Detector Block Diagram
9E-4-2
9E-4-16. Frequency Multiplier

9E-4-20. Assume, however, the channel B frequency
increases. This causes the negative pulses at U22(1) to
arrive a little earlier than before, arriving ahead of the
edges at pin 3. When an edge arrives at pin 1, the UP
output goes active low and stays low until the edge at pin 3
arrives. The UP output, then, begins generating active low
pulses. They are inverted into positive pulses that forward
bias CRB Current flows through CRB and RBI into the
integrator amplifier U23, causing the tuning voltage to
integrate downward, this increases the PLO's output and
increases the feedback frequency at U22 pin 3. This
process continues until the signals at U22 pins 1 and 3 are
again matched in frequency and phase. The phase detector
outputs are inactive hi
g
h, and the loop is at reset.
9E-4-21. THE VCO. The phase detector's corrections are
integrated and saved by the loop amplifier, an integrating
amplifier (refer to A1 schematic). This makes a tuning
voltage that sets the frequency of the VCO (voltage-
controlled oscillator). The oscillator is a sawtooth
generator driving a Schmitt trigger. The voltage-controlled
current source (Q16) charges capacitor C42 in a linear
ramp until the ramp reaches about +2.4 volts. This goes
through an emitter follower (Q17) and appears at U24C(9)
at + 1.8 volts. This is the upper trigger point on the
Schmitt gate. The output of U24C snaps low and
discharges C42 through CR21 to about +0.6 volts. This is
below the negative threshold, so the Schmitt output snaps
high and the sawtooth starts again. The negative pulse
train at U24C(8) is used as the PLO output, and it is this
frequency that is counted by the decade counter. The
waveforms would appear as follows in Fi
g
ure 9E-4-2.
Fi
g
ure 9E-4-2. VCO Waveforms at about 2 MHz
9E-4-22. When the VCO is running at much less than 10
MHz, it becomes very difficult to see the narrow pulses at
U24C(8) on a scope. It is easier to see the sawtooth or a
squarewave at half the VCO frequenc
y
at U21(9).
Model 5305B
Theor
y
of Operation
It is important to remember that the frequency/tuning
voltage (U23 pin 6) is a negative relationship. That is, the
lower the tunin
g
volta
g
e, the hi
g
her the frequenc
y
.
9E-4-23. SEARCH INDICATOR CIRCUIT. The VCO
runs continuously whether the loop is locked (normal
operation) or not. In the high resolution range, there is
always a signal from the VCO to the 5305B counting
circuitry, whether or not there is a signal at the Channel B
input. As a result, the counter is always armed and tries to
count the VCO frequency (typically 25 kHz) even without
an input. This is prevented by the search indicator circuit,
U16A, U18C, U24A, Q19.
9E-4-24. When the detector's inputs are in phase, the U22
output pins (2 and 13) are always TTL high. If the loop is
not locked, one or the other will be low much of the time.
Whenever either is low, U24B(6) is high, signaling an
error in the loop. These error pulses are averaged by R77,
R78, and C36. If the errors are large enough, the LOST
line from comparator U16A will snap low in about 50
msec. In the high resolution range, LOST passes through
gate U18C and becomes STOP (active high). STOP lights
the SEARCH lamp (S annunciator) through Q14 and gates
off the 10 MHz clock at U10A. This prevents the counter
from continuing with more measurements or display
updates and saves the last valid reading in the display.
LOST enables gates U18 Band D, which pass the phase
correction signals through resistor R76 (5.1KΩ). R76 is in
parallel with R81 (82KΩ, so R81 is effectively reduced
from 82K ohm to about 5K ohm. This greatly increases
loop bandwidth and allows for rapid searches and short
acquisition times.
9E-4-25. When an in-range input signal is restored to
Channel B, the loop will lock. The phase corrections stop,
U24B(6) (the error signal) stays low, and C36 discharges
through R77 (100K ohm). As the average error signal
drops through +1 volt, the lower threshold, U16A(1) snaps
high, and STOP goes low. U24A(3) inverts this negative
edge into a positive edge and Q19 is switched on for about
0.1 seconds. This clears all the counters and the time base,
so a new measurement is begun, making the first reading
correct. Meanwhile the SEARCH light is switched off,
and the loop bandwidth is reduced to a low value to allow
p
roper stabilit
y
for accurate measurements.
9E-4-26. NON-LINEAR VCO CHARACTERISTIC.
When no signal is available at the PLO input, the VCO is
tuned to its lowest frequency (about 25 kHz). If a high
frequency (e.g., 10 kHz) is applied, the VCO must be
slewed all the way to 10,000 kHz to achieve lock. This
would take a loop that is stable at 50 Hz almost two
minutes to achieve lock. Therefore, gates U18 Band D,
were added, and the VCO characteristic has a bend in it.
See Fi
g
ure 9E-4-3.
9E-4-3

Model 5305B
Theor
y
of O
p
eration
9E-4-27. This puts a step in the loop bandwidth at about
300 Hz input, increasing loop bandwidth drastically above
300 Hz. (Higher loop bandwidth is allowable at higher input
frequencies.) This greatly reduces acquisition time for a 10
kHz input.
9E-4-28. This "bend" in the VCO curve is accomplished by
CR24 and R90. The corrected tuning voltage is the voltage
between Q16's emitter and the +12 volt supply. The current
is set by the resistance between those points. For corrected
tuning voltages less than about 2 volts (actual tuning voltage
above +9.4 vots), the tri-diode CR24 is off and out of the
circuit. The effective resistance is R90 plus R83, or about
6500 ohms. For larger corrected tuning voltages (higher
frequencies), the tri-diode is on and shorts R90, removing it
from the circuit. Now the effective resistance is R83, or 270
ohms.
9E-4-29. MISCELLANEOUS A1 CIRCUITS. R84 (330K
ohm) sets the lowest VCO frequency at about 25 kHz,
corresponding to a 25 Hz input. Otherwise, the VCO could
actually go to 0 Hz, and the phase detector outputs would go
high because the VCO would appear to be locked to a 0 Hz
input (no input). This would turn off the search indicator.
C47 (100 pF) sets the width of the narrow low-going pulse
at the VCO output, U24C(8). Diode CR17 prevents the
tuning voltage from going too low when the loop tries to
acquire an excessive high input signal (above 11 kHz). Pin 3
of the loop amplifier is biased at + 1.5 volts. This forces pin
2 to also be at + 1.5V which is a good bias point to allow
p
roper operation of the diode switches.
9E-4-4
9E-4-30. 1300 MHz ÷Circuit
9E-4-31. The A2 board amplifies the Channel A signal and
then divides it by four before sending it to A1 via J2(9). U26
divides the EECL signal by two before Q18 converts the
signal to ECL. Another divide-by-two stage is provided by
U25. Differential amplifier Q12 and Q13 converts the signal
to a positive driven ECL (H = 4.3V, L = 3.2V). Q11
p
rovides a low impedance to U12's input.
9E-4-33. The 1300 MHz Amplifier assembly (A2) consists
of circuitry to amplify, prescale, and detect signals up to
1300 MHz. Input signals are routed through a protective fuse
F1 to the 1.3 GHz limiter circuitry. The limiters consist of
CR2, 7, 1, 4 and limit the input to approximately 5V rms. A
voltage controlled attenuator made up of pin diodes CR5, 6,
8, and 9 provides variable attenuation as determined by an
AGC circuit.
9E-4-34. The attenuator output connects to U2 which
provides 20-24 dB gain. U3 divides the signal by 2 and
routes it to U4 where it is divided by 2 again. Since U3 has
no Schmitt trigger, U3 is set for maximum sensitivity.
Operating at maximum sensitivity gives U3 a tendency to
oscillate when no input signal is applied. To maintain high
sensitivity and prevent oscillations, R22 is adjusted to
desensitize U3 when the ARM line is high and produce high
sensitivity when the ARM line is low. This allows the
counter readings to "snap on" from no input signal to the
exact reading when a signal is applied. The amount of "snap
on" feedback is controlled by A1R71. The greater the "snap
on" feedback, the less the possibility of partial counts, but
also the lower the sensitivit
y
.
9E-4-35. As the input level increases, the level into A2U1
increases. A bridge circuit comprised of CR11, CR12 and
associated resistors including R13 which balances the
bridge. As the input level to the bridge increases, the
rectified bridge output drives the input to U1 to cause the
output of U1 to go low. This reduces the amount of current
through A1R9, R1 (sen. pot), L4, L1, CR6, CR8, and R11.
As the current through this path decreases, the resistance of
the PIN diodes (CR6, 8) increases to offer more attenuation
to the input signal. Similarly, the current increases through
CR9, R10, R1, R3, R6, R7, CR5 and R2, which decreases
the resistance of CR5 and CR9 to shunt more of the signal to
g
round throu
g
h C5 and C9.
Figure 9E-4-3. VCO Characteristics
9E-4-32. A2 1300 MHZ AMPLIFIER ASSEMBLY

Model 5305B
Maintenance
SECTION IX E
5305B 1300 MHz COUNTER
SUBSECTION V
MAINTENANCE
9E-5-1 INTRODUCTION
9E-5-2. This subsection contains maintenance information
for Model 5300/5305B 1300 MHz Counter. Performance
checks, adjustment procedures, and tests to isolate defective
components are included.
9E-5-3. RECOMMENDED TEST EQUIPMENT
9E-5-4. Test equipment recommended for performance
checking and servicing the 5300B/5305B 1300 MHz Counter
is listed in Table 9E-1-1 and in Table 5-1 in the 5300B
portion of the manual. Test equipment with equivalent
characteristics ma
y
be substituted for listed equipment.
9E-5-5. IN-CABINET PERFORMANCE CHECK
9E-5-6. Use the performance check in Table 9E-5-1 and
the test card at the back of this subsection to verify proper
operation of all circuits in the counter and all circuits in the
5300 that are used with the counter plug-on. The performance
check ma
y
be used:
a. As part of an incoming inspection check of instrument
specifications.
b. Periodically, for instruments used in systems where
maximum reliability is important.
c. As part of a procedure to locate defective circuits.
d. After any repairs of adjustments, before returning
instrument to re
g
ular service.
9E-5-7. INSTRUMENT ACCESS
9E-5-8. For access to the plug-on assembly, separate the
5300 from the 5305B as follows:
a. Turn ac power OFF and disconnect power cord.
b. Pull the two side casting latches fully rearward ( it is
necessary to press the latch handles gently away from
the center of the instrument to unlock them).
c. When latches are fully extended rearward, the 5300
and 5305B cast housings should be separated by
about 1/8-inch.
d. Lift the 5300 gently away from the 5305B.
e. Separate 5305B Board Assembly from the cast
housing as follows (refer to Figure 9E-5-1):
(1) Press rear, plastic-nylon retaining clips on each
side of 5305B casting and lift the rear of the
5305B Assembly to release it from the casting.
(2) Press front plastic-nylon retaining clips on each
side of 5305B casting and lift the front of the
Board Assembly to release it from the casting.
(3) Lift Board Assembly from the casting.
f. Mate the 5305B Board Assembly to the 5300 and apply
ac power.
g. To reinstall the Board Assembly into the casting,
reverse procedure of steps d throu
g
h f.
9E-5-9. PERIODIC MAINTENANCE
9E-5-10. To determine if the 5300B/5305B is operating
properly, perform the In-Cabinet Performance Checks
listed in Table 9E-5-1.
9E-5-11. MAINTENANCE AND REPAIR
9E-5-12. BOARD REMOVAL. When removing the
printed circuit board for replacement, repair, or servicing,
always remove ac power and separate the board from the
castin
g
accordin
g
to Para
g
raph 9E-5-8, steps a to e.
9E-5-13. COMPONENT REPLACEMENT. When re-
placing a circuit board component, use a low heat soldering
iron. Heat may be used sparingly as damage to the circuit
foil may result. Mounting holes may be cleaned out with a
toothpick while heat is applied. Connection should be
cleaned with a cleaning solution after component removal
and replacement.
9E-5-1