HP 5326A Service manual

5326A/5327A
TIMER/COUNTER
OPERATING AND SERVICE MANUAL
SERIAL PREFIX:
5326A — 1136 A
5327A — 1120 A
This manual applies to HP Model 5326A having serial
prefix 1136A and HP Model 5327A having serial
prefix 1120A.
SERIAL PREFIXES NOT LISTED
For serial prefixes above 1136A (5326A) and 1120A
(5327A), a “Manual Supplement” sheet is included
with this manual. For serial prefixes below 1136A and
1120A, refer to Section VII of this manual.
Copyright HEWLETT-PACKARD COMPANY 1972
5301 STEVENS CREEK BLVD., SANTA CLARA, CALIF. 95050
Printed: MAR 1972
THIS MANUAL PRINTED ON 100% RECYCLED PAPER
HEWLETT M PACKARD

Model 5326/27A
General Information
Figure 1-1. HP Model 5326A/5327A Timer/Counter

Model 5326/27A
General Information
SECTION I
GENERAL INFORMATION
1-1. DESCRIPTION
1-2. The Hewlett-Packard Models 5326A/5327A are
frequency counters that have a variety of functions.
The basic difference between the two models is the
addition of the prescaler assembly in the 5327A. This
assembly increases the upper frequency limit from
50 MHz to 550 MHz. The 5326A uses a high-
sensitivity, 50-ohm input amplifier in place of the
prescaler.
1-3. The instruments measure frequency, period,
period average, time interval, time interval average,
and ratio. Features include a 7-digit display (8-digits
optional), 1M ohm and 50-ohm inputs, display
storage, and blanking for insignificant digits in the
display. Decimal point and unit readouts are dis¬
played automatically with each operating selection.
Two independent input channels are provided for
time interval measurements. Each input channel has
an attenuator, trigger slope selector, level control,
ac-dc coupling, and an oscilloscope marker output.
Table 1-1 lists the electrical and mechanical
specifications.
1-4. IDENTIFICATION
1-5. Hewlett-Packard uses a two-section serial num¬
ber mounted on the rear panel. Earlier instruments
use an 8-digit serial number (000-00000). The first
three digits are a serial prefix number; the last five
digits refer to the specific instrument. Later instru¬
ments use a 9-digit serial number (0000A00000). The
first four digits are the serial prefix and the last five
digits refer to the specific instrument. 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. Lower
serial prefixes are documented in Section VII, and
higher serial prefixes are covered with manual change
sheets included with the manual. If the change sheet
is missing, contact the nearest Hewlett-Packard Sales
and Service Office listed on the inside rear cover of
this manual.
1-6. APPLICATIONS
1-7. The 5326A/5327A Counters are particularly
adaptable to timing measurements such as pulse
width, pulse repetition frequency, and propagation
delay. The time interval average mode measures time
interval on repetitive signals with resolution better
than one nanosecond. When used with microwave
test systems, group delay, phase, and level measure¬
ments can be performed.
1-8. OPTIONS
1-9. The instrument can be ordered with the following
options: Option 001, 8-digit display; Option 002, re¬
mote programming; Option 003, digital recorder out¬
puts; and Option 004, remote programming for all
signal input conditions.
Table 1-1. Equipment Supplied
Description
HP Part. No.
Detachable Power Cord, l l A 8120-1348
ft. (231 cm) long
Rack Mounting Kit 05326-60029
Table 1-2. Accessories Available
Description
HP Part No.
Digital Recorders
5050B, 5055A
Interconnect Cable, Digital
Recorder, 6 ft. (183 cm)
562A-16C
50-ohm BNC to BNC Coaxial
Cable, 4 ft. (122 cm)
10503-6001
Circuit Board Extender,
15-pin (two required)
5060-0049
Input Amplifier Circuit Board
Extender
10532-60001
Circuit Board Extender,
18-pin
5060-2041
Extender Board Kit; includes
two 5060-0049, and one each
5060-2041, and 10532-60001
10532A
1-1

Model 5326/27A
General Information
Table 1-3.
INPUT CHANNELS A AND B
Range:
dc coupled: 0-50 MHz
ac coupled: 20 Hz - 50 MHz
Sensitivity:
0.1 V rms sine wave
0.3 V p-p pulse
8 ns minimum pulse width
Sensitivity can be decreased by 10 or 100
times, using the ATTENUATOR switch.
Impedance: 1 MO shunted by less than 25 pF
Dynamic Input Voltage Range:
0.1 to 3 V rms ac times attenuator setting
±5 Vdc times attenuator setting.
Trigger Level:
PRESET to center triggering about 0 V or
variable over the range of -3 V to +3 V times
attenuator setting. Trigger threshold band
<1.0 mV, referred to input at maximum
frequency.
Overload Protection:
250 V rms on all attenuator settings, except
25 V rms on XI above 50 kHz.
Slope:
Independent selection of positive or negative
slope.
Channel Inputs: Common or separate lines.
Marker Outputs:
Rear panel BNC’s DTL pulse, low for
approximately 2 ps after trigger point for A
and B channels.
INPUT CHANNEL C
5327A
Range:
direct: 1 kHz - 50 MHz, ac coupled
prescaled: 0-550 MHz, dc coupled
Sensitivity:
direct: 5 mV rms
prescaled: 100 mV rms
Impedance: 500 nominal
Maximum input: 5 volts rms; 7.5 volts peak
Trigger Level: 0 volts
5326A
Range: 0 to 50 MHz, dc coupled
Sensitivity:
5 mV rms
Specifications
Impedance: 500 nominal
Maximum Input: 5 volts rms; 7.5 volts peak
Trigger Level: 0 volts
CAUTION
Do not exceed voltage specification
or damage will occur.
START (Totalizing and Scaling)
Range: 0 - 10 MHz
Factor: 1 -10* selectable in decade steps
Output: Rear panel TIME BASE BNC
Display:
Channel A input divided by scaling factor
FREQUENCY
Range:
0 - 50 MHz (5326A)
0 - 550 MHz (5327A)
Input:
Channel A; channel C for direct and for
prescaled (switchable). Channel A provides
triggered frequency measurement
Gate Times: 0.1 ps to 10 s in decade steps
Accuracy:
Direct: ±1 count ± time base accuracy.
Prescaled: ±10 counts* ± time base accuracy
Display:
kHz, MHz, or GHz with positioned decimal
point
TIME INTERVAL
Range: 0.1 ps to 10 9 seconds
Input:
Channels A and B; can be common or
separate
Frequency Counted:
10 MHz to 0.1 Hz in decade steps
Accuracy:
±1 count ± time base accuracy ± trigger
error.**
Display:
ps, ms, seconds or 10’s of seconds with
positioned decimal point
TIME INTERVAL AVERAGE
Range: 0.15 ns to 10 s
Intervals Averaged:
1 -10 8 selectable in decade steps
*±10 counts of input frequency (±1 count displayed).

Model ,5326/27A
General Information
Table 1-3. Specifications (Continued)
Input:
Channels A and B; can be common or separate
Frequency Counted: 10 MHz
Minimum Time Stop to Start: 150 ns
Accuracy: ± time base accuracy ± 2 ns
(trigger error** -el00 ns)
Display: ns, /as with positioned decimal point
PERIOD
Range: 0-10 MHz
Input: Channel A
Frequency Counted:
10 MHz to 0.1 Hz in decade steps
Accuracy:
±1 count ± time base accuracy ± trigger
error.***
Display:
/as, ms, seconds or 10’s of seconds with
positioned decimal point
PERIOD AVERAGE
Range: 0 -10 MHz
Periods Averaged: 1 -10 8 selectable in
decade steps.
Input: Channel A
Frequency Counted: 10 MHz
Accuracy:
± time base accuracy ± 1 count ± trigger
error***
Display: ns, ms, with positioned decimal
point
RATIO
Display:
F A /F e xt or F C /F ex t times MULTIPLIER (M).
M = 1 to 10*, selectable in decade steps
Range:
Fa (Channel A or Channel C) 0 - 50 MHz
F ex t (External Oscillator Input) 100 Hz to
10 MHz
Mode:
Operating mode will be either FREQUENCY
A or FREQUENCY C
Accuracy:
± 1 count of F A ± trigger error of F ex t
TIME BASE
Crystal Frequency: 10 MHz
Stability:
Aging Rate: <3 parts in lOVmo.
Temperature: <±2.5 parts in I0 fi , 0° to 50°C.
Line Voltage: <±1 part in 10 T for 10% line
variation.
Short-term Fluctuation: Typically <5 parts
in 10 9 , one-second average (at con¬
stant temperature)
Oscillator Output:
10 MHz, TTL type output levels, 50Q series
impedance at rear panel BNC
External Input: 100 Hz -10 MHz; 1 V rms into IkO
Time Base Output:
Negative pulses, ±3 V to 0 V (open circuit),
typically 100 ns wide. In START, output is
10 MHz divided by TIME BASE/MULTIPLIER
switch setting. Available at rear panel BNC.
Gate Output:
TTL level pulses; low while gate open, high
while gate closed. Available at rear panel
BNC.
GENERAL
Display: 7 digits (8 optional)
Blanking:
Suppresses display of unwanted zeros left of the
most significant digit
Display Storage:
Holds reading between samples. Rear panel
switch overrides storage
♦♦ For any waveshape, trigger error is less than
00025
Signal Slope (V/ms)
***Trigger error is less than ±0.3% of one period
* periods averaged for signals with 40 dB or
better signal-to-noise ratio and 100 mV rms
amplitude.
intervals averaged
1 -

Mode) 5326/27A
General Information
Table 1-3. Specifications (Continued)
Sample Rate:
FAST position: Continuously variable from less
than 100 pts to approximately 20 ms. NORM
position: Continuously variable from less than
20 ms to approximately 5 seconds. HOLD
position: Display can be held indefinitely.
Overt low:
Neon indicates when display range is exceeded.
Operating Temperature: 0° to 50°C
Power Requirements:
115 or 230 volts ±10%, 50 to 60 Hz, 70 watts
maximum
Weight:
Net, 16 lb.(7,4 kg). Shipping, 18 lb. 16 oz(8,7 kg)
Accessories Furnished:
Power Cord, 7% ft. Rack Mount Kit.
Dl^EMSIONS
ACCESSORIES AVAILABLE
HP 10503A, 50Q BNC Cable, 4 ft (122 cm)
HP 10532A, Extender Board Kit containing 2 ea.
15-pin extender 5060-0049, 1 ea. 18-pin
extender 5060-2041, and 1 ea. Amplifier
Extender, 10532-60001
IIP10542A, Remote Programming Interface
enables interfacing between the 5326/5327
Series counter with Option 004 and 40-bit
Output Register. Includes two (2) 7-bit
Digital-to-Analog Converters for level controls
and decoding for time base and function
selector.
HP Cable 562A-16C, 6 ft. (183 cm) to connect
5326/5327 Series with Option 003 to HP 5050B
or 5055A Digital Recorder
Option 001 : 8-digit display
Option 002: Remote programming
Controls:
All front panel controls are single line program¬
mable except:
SEP-COM (separate-common) switch; the check
function is programmable
FAST/NORM Mode
Input Attenuators
AC/DC Input Signal Coupling
Control Signal:
Single line control using either contact closure to
ground or DTL drive on all lines except trigger
levels which are analog programmed (±3 Vdc)
Connector
Rear panel connector: HP 1251-0085; Amphenol
57-40300-375. (36-pin blue ribbon).
Mating connector: HP 1251-0084; Amphenol
57-30360-375
Option 003: Digital output (for numerals and
polarity only)
Code:
4-line 1-2-4-8 BCD, “1” state high. “0” state
+0.25 V at -1 tnA; “1” state: +5 V open circuit,
2.5 kQ source impedance nominal
Print Command:
+5 V to 0 V, dc coupled: occurs at end of gate.
Storage:
Buffer storage is provided so BCD output is
constant while next measurement is being
made
Inhibit Input:
Inhibits gate when instrument’s cycle time is
less than the time required for external
equipment to interrogate BCD outputs.
Positive inhibit +5 Vdc
Connector:
Rear panel connector: HP 1251-0087;
Amphenol 57-40500-375 (50-pin blue ribbon).
Mating connector: HP 1251-0086; Amphenol
57-30500-375
Option 0G4: Remote Programming including
all signal input conditions.
Controls:
All front panel controls are programmable
except FAST/NORM Mode.
Control Signal:
Single line control using either contact
closure to ground or DTL drive on all lines
except trigger levels which are analog
programmable (±3 Vdc).
Connector:
Rear panel connector: HP 1251-0087;
Amphenol 57-40500-375 (50-pin blue ribbon)
Mating Connector: HP 1251-0086; Amphenol
57-30500-375

Model 5326/27A
Installation
2-1. INTRODUCTION
2-2. This section contains information for unpacking,
inspection, repacking, storage, and installation. The
instructions for remote programming are also given
in this section.
2-3. UNPACKING AND INSPECTION
2-4. If the shipping carton is damaged, ask that the
carrier’s agent be present when the instrument is un¬
packed. Inspect the instrument for damage (scratches,
dents, broken knobs, etc.). If the instrument is
damaged or fails to self-check (Self-Check Procedures,
Table 3-1), notify the carrier and nearest Hewlett-
Packard Sales and Service Office immediately (offices
are listed at the back of this manual). Retain the
shipping carton and padding material for the carrier’s
inspection. The sales and service office will arrange
for the repair or replacement of your instrument with¬
out waiting for the claim against the carrier to be
settled.
2-5. STORAGE AND SHIPMENT
2-6. PACKAGING. To protect valuable electronic
equipment during storage or shipment always use the
best packaging methods available. Your Hewlett-
Packard Sales and Service Office can provide packing
material such as that used for original factory pack¬
aging. Contract packaging companies in many cities
can provide dependable custom packaging on short
notice. Here are two recommended packaging-
methods:
a. RUBBERIZED HAIR. Cover painted surfaces
of instrument with protective wrapping paper. Pack
instrument securely in strong corrugated container
(350 lb/sq. in. bursting test) with 2-inch rubberized
hair pads placed along all surfaces of the instrument.
Insert fillers between pads and container to ensure a
snug fit.
b. EXCEI^SIOR. Cover painted surfaces of in¬
instrument with protective wrapping paper. Pack
instrument in strong corrugated container (350 lb/sq.
in. bursting test) with a layer of excelsior about six
inches thick packed firmly against all surfaces of the
instrument.
2-7. ENVIRONMENT. Conditions during storage and
shipment should normally be limited as follows:
a. Maximum altitude: 25,000 feet.
b. Minimum temperature: -40°F (-40°C).
c. Maximum temperature: +167°F(+75°C).
2-8. RACK INSTALLATION
2-9. The counter is ready for bench operation as
shipped from the factory. Additional parts necessary
for rack mounting are packaged with the instrument.
To convert to rack installation, proceed as follows:
a. Remove tilt stand.
b. Remove feet (press the foot-release button,
slide foot toward center of instrument, and lift off).
c. Remove adhesive-backed trim strips at front
end of sides.
d. Attach filler strip along bottom edge of front
panel using two screws on outer edges of filler strip.
Omit the center screw.
e. Attach flanges to front end of sides (larger
comer notch toward bottom of instrument). Instrument
is now ready to mount in standard rack.
CAUTION
Ambient temperature in rack during
operation should not exceed 122°F
(50''C). Be sure instrument position in
rack permits adequate air circulation
and that nearby equipment does not dis¬
charge hot air directly on the instrument.
2-10. POWER CONNECTION
2-11. LINE VOLTAGE. The counter may be operated
from either 115 or 230 volt (±10%) power lines with
frequencies from 50 to 60 Hz. A slide switch on the
rear panel permits quick conversion for operation
from either voltage. Insert a narrow-blade screw¬
driver in the switch slot and slide the switch to the
right for 230 volt operation (“230” marking exposed)
or to the left for 115 volt operation (“115” marking
exposed). The counter is supplied with a 115 volt
fuse; be sure to change this fuse for 230 volt operation,
see Table 2-1.
CAUTION
Before plugging instrument to ac power
line be sure slide switch is properly
positioned.
2-1

Model 5326/27A
Installation
Table 2-1. 115/230 Volt Conversion
Line Voltage
Conversion
115 Volt 230 Volt
Slide Switch Left (1.15) Right (230)
AC line Fuse 1.50 Ampere
(Slow-Blow)
(HP 2110-0304)
0.8 Ampere
(Slow-Blow)
(HP 2110-0020)
2-12. POWER CABLE. The counter is equipped with
a detachable 3-wire power cable. Proceed as follows
for installation.
a. Connect plug (3-socket connector) to ac line
jack at rear of instrument.
b. Connect plug (2-blade with round grounding
pin) to 3-wire (grounded) power outlet. Exposed
portions of instrument are grounded through the
round pin on the plug for safety; when only 2-blade
outlet is available, use connector adapter (HP Part
No. 1251-0048), then connect short wire from side of
adapter to ground.
2-13. REMOTE PROGRAMMING, OPTION 002
2-14. The following paragraphs describe remote pro¬
gramming requirements for the counter with Option
002. See Paragraph 2-33 for Option 004 programming.
2-15. Front Panel Controls
2-16. The following front-panel controls are program¬
mable:
a. FUNCTION
b. TIME BASE/MULTIPLIER
c. CHECK function
d. SLOPE
e. SAMPLE RATE and HOLD
f. LEVEL controls
g. INPUT C switch (5327A only)
h. RESET
2-17. The following front-panel controls are NOT
programmable:
a. AC/DC
b. SEP-COM
c. FAST/NORM
d. ATTEN
2-18. The trigger level controls may be remotely pro¬
grammed or the front-panel LEVEL controls may be
used. It is possible to program the LEVEL controls
without programming the remainder of the front-
panel controls. When remote programming is used,
the LEVEL controls must be set to PRESET. Display
time may be remotely programmed and/or the front-
panel controls may be used.
2-19. Remote Programming Requirements
2-20. All lines may be controlled by TTL or DTL
signals or contact closure to ground when the unit is
being remotely programmed: except the trigger levels
which are programmed by an analog level (if pro¬
grammed) and the display time line (Hold), J10 pin
35, which should NOT be pulled up to +5 V by less
than 200Q while programming.
2-21. When the unit is NOT being programmed (Ext
line high), all the lines should be left open or pulled up
to +5 V by not less than 5kO, except the trigger levels,
which should be open circuited.
2-22. Remote Programming Procedure
2-23. In order to remotely program the counter, the
following must be done:
a. Set FUNCTION switch to any function but
START or STOP.
b. Ground the EXT line at rear-panel REMOTE
PROGRAM connector J 10(17). This disables the
front panel switches. Ground is available at J 10(36).
c. Select the desired function.
d. Select the desired time base.
e. Select the slope ( + or -) for CHANNEL A and
B. This is accomplished by grounding the Slope line
for (-) and leaving it open for (+). Slope A line is
J10(28). Slope B line is J 10(29).
f. Select the trigger level for input signal.
g. Adjust the display time.
h. Manual reset is available by grounding (<.7 V)
pin 34. Check is available by grounding pin 14.
2-2

Model 5326/27A
Installation
2-24. Function Selection Programming
2-25. To program the desired function, ground (<.7 V)
the proper line at J10 as follows:
STOP
Pin 32
START
Pins 1 and 32
PERIOD AVERAGE Pin 2
T.I. AVG.
Pin 3
T.I. A to B Pin 4
PERIOD
Pin 5
FREQ. A Pin 6
FREQ. C DIRECT Pin 7
FREQ. C + 10
Pins 7 and 18
2-26. Time Base Selection Programming
2-27. To program the Time Base, ground (<.7 V) the
proper line at J10 as follows:
.1 p s/1
Pin 19
1 ps/10
Pin 20
10 ps/10 2
Pin 21
.1 ms/l0 :J
Pin 22
1 ms/'10 4
Pin 23
10 ms/10 5
Pin 24
.1 s/10 6
Pin 25
1 s/10 7
Pin 26
10 s/10 8
Pin 27
2-28. Trigger Level Programming
2-29. To program the trigger level, the LEVEL con¬
trols must be set to PRESET. Select the trigger level
by placing a dc voltage between -3.0 and +3.0 volts on
the level input line (Level A = JIO pin 30, Level B = JiO
pin 31). This voltage, times the attenuator setting, is
the trigger level. Preset is programmed by leaving the
pin open on contact closure to ground. Grounding
is preferable if noise exists on the remote program¬
ming line.
2-30. The front-panel LEVEL controls may be used
manually if programming of the trigger levels is un¬
desirable. Also, note the AC/DC and ATTEN switches
on the front-panel must be set manually, as they are
NOT programmable.
2-31. Sample Rate Adjustment
2-32. Adjusting the display time can be accomplished
in several ways:
a. Manually adjust the display time by using the
front-panel SAMPLE RATE controls.
b. Set the SAMPLE RATE control cw and the
FAST/NORM/HOLD switch to NORM and connect a
1 megohm pot in series with a 1.5k ohm resistor from
+5 V to pin 35. This will give a display time range of
about 10 ms to 5 sec. If a shorter time is desired, set the
FAST/NORM/HOLI) switch to FAST, which gives a
range of about 50 ps to 10 ms.
c. Set the SAMPLE RATE control cw in FAST
and hold the Hold line (pin 35) to ground for the desired
display time. The display will continue for about 100
ps after the ground is released.
2-33. REMOTE PROGRAMMING, OPTION 004
2-34. The following paragraphs describe remote pro¬
gramming requirements for the counter with Option
004.
2-35. Front Panel Controls
2-36. All front-panel controls are programmable, ex¬
cept the FAST/NORM/HOLD switch. The trigger
level controls may be remotely programmed, or the
front-panel LEVEL controls may be used. It is pos¬
sible to program the front-panel LEVEL controls with¬
out programming the remainder of the front-panel
controls. When remote programming the trigger
levels, the LEVEL controls must be set to PRESET.
The display time may be remotely programmed and/
or the front-panel controls may be used.
2-37. Remote Programming Requirements
2-38. All lines may be controlled by TTL or DTL
signals or contact closure to ground when the unit is
being remotely programmed: except the trigger levels
which are programmed by an analog level (if pro¬
grammed) and the display time line (Hold), J10 pin 16,
which should NOT be pulled up to +5 V by less than
200H while programming.
2-39. When the unit is NOT being programmed (EXT
line high), all the lines should be left open or pulled
up to +5 V by not less than 5kQ, except the trigger
levels, which should be open circuited.
2-3

Model 5326/27A
Installation
2-40. Remote Programming Procedure
2-41. In order to remotely program the counter, the
following must be done:
a. Set FUNCTION switch to any position but
START or STOP.
b. Ground the EXT line at rear-panel REMOTE
PROGRAM connector J 10(34). This disables the
front panel switches. Ground is available at J10(36).
c. Select the desired function.
d. Select the desired time base.
e. Select the signal conditioning.
f. Select the trigger level for input signal.
g. Adjust the display time.
h. Manual reset is available by ground (<.7 V)
pin 17. Check is available by grounding pin 37.
2-42. Function Selection Programming
2-43. To program the desired function, ground (<.7 V)
the proper line at J10 as follows:
STOP Pin 19
START
Pins 46, 19
PERIOD AVERAGE Pin 47
T.I. AVG.
Pin 45
T.I. A to B Pin 44
PERIOD
Pin 43
FREQ. A Pin 42
FREQ. C DIRECT Pin 41
FREQ C + 10
(5327A only)
Pin 33
2-44. Time Base Selection Programming
2-45. To program the time base, ground (<.7 V) the
proper line at J10 as follows:
.1 jis/1
Pin 28
1 /u,s/10
Pin 29
10 ms/10 2 Pin 27
.1 ms/10 3 Pin 26
1 ms/10 4
Pin 25
10 ms/10 5 Pin 24
.1 s/10 6 Pin 30
1 s/10 7
Pin 31
10 s/10 8 Pin 32
2-46. Signal Conditioning Programming
2-47. Program the input conditions by grounding the
proper line as follows:
CONDITION
LINE
J10
INPUT
AC/DC A
11 AC=H DC=L
SLOPE A
23 + = H * = L
ATTENUATOR A
13,14 13-H, 14 - H = XI
13-L, 14- H=X10
13-H, 14 - L= X100
AC/DC B
7
AC = H DC = L
SLOPE B
22
+ = H - = L
ATTENUATOR B
9, 10
9 - H, 10 - H = XI
9 - L, 10 -H = X10
9- H, 10 - L = X100
SEP/COM
6 COM = L, SEP = H
CHECK
37
CHK = L
2-48. Trigger Level Programming
2-49. To program the trigger level, the LEVEL con¬
trols must be set to PRESET. Select the trigger level
by placing a dc voltage between -3.0 and +3.0 volts
on the level input line (Level A = J10 pin 21, Level B
= J10 pin 20). This voltage, times the attenuator
setting, is the trigger level. Preset is programmed by
leaving the pin open or contact closure to ground.
Grounding is preferable if noise exists on the remote
programming line.
2-50. The front-panel LEVEL controls may be used
manually if programming of the trigger levels is
undesirable.
2-51. Sample Rate Adjustment
2-52. Adjusting the display time can be accomplished
in several ways:
a. Manually adjust the display time by using the
front-panel SAMPLE RATE controls.
2-4

Model 5326/27A
Installation
b. Set the SAMPLE RATE control cw and the
FAST/NORM/HOLD switch'to NORM and connect a
1 megohm pot in series with a 1.5k ohm resistor from
+5 V to pin 16. This will give a display time range of
about 10 ms to 5 sec. If a shorter time is desired, set
the FAST/NORM/HOLD switch to FAST, which gives
a range of about 50 /as to 10 ms.
c. Set the SAMPLE RATE control cw in FAST
and hold the Hold line (pin 16) to ground for the
desired display time. The display will continue for
about 100 /as after the ground is released.
2-53. BLANKING DEFEAT
2-54. This counter is designed to blank insignificant
zeros (zeros to left of data). When blanking occurs,
the digital recorder output for the blanked columns is
BCD 15 (HHHH). To use this instrument with a
digital-analog converter, it is necessary to defeat the
blanking feature by repositioning the 1 two jumpers on
the A9 Display board. Move the jumpers to position 2,
as shown in A9 Component locator (Section VIII).
This connects pin 10 of A9U7 and A9U8 to +5 V. Also,
lift the pin 1 lead of A8U2 and connect pin 1 to ground
(available at U2 pin 7).
2-5

Model 5326/27A
Operation
SECTION IS
3-1. INTRODUCTION
3-2. Section III contains the operating information
required to obtain the most effective performance
from the instrument. This includes a general descrip¬
tion of the operating modes, the function of ail con¬
trols and indicators, a self-check procedure, and setup
procedures for making basic measurements.
3-3. OPERATING MODES
3-4. The following paragraphs describe the operating
modes of totalize, frequency, period, time interval,
and ratio.
3-5. Totalize Mode
3-6. START and STOP positions on the FUNCTION
selector allow manual opening and closing of the
counter’s main gate. When the switch is in the START
position, the counter does not measure frequency, but
instead, counts the number of times the signal passes
through the trigger point. The input signal, connected
to the front-panel CHANNEL A jack, is divided by the
MULTIPLIER switch setting prior to counting. For
example, when the MULTIPLIER switch is set to the
1 position, every pulse is counted. When the switch is
set to 10 ;i , the counter registers every thousandth
pulse. When the FUNCTION switch is set to STOP,
the counter stops totalizing and holds the displayed
count until the RESET switch is pressed or the
MULTIPLIER switch setting is changed. If the
FUNCTION switch is again set to START before a
reset is generated, the count continues to totalize
from the previously displayed value. With the FUNC¬
TION switch set to START, the scaled input signal
is available at the rear-panel TIME BASE OUTPUT
jack. The unit indicators and decimal points are
blanked during the totalize mode. The C light is
on (in START), indicating counting is taking place.
3-7. Frequency Modes
3-8. Three frequency modes are available in the
5327A: Frequency A, Frequency C prescaled, and Fre¬
quency C direct, (The prescale operation is not in¬
cluded in the 5326A.) In the Frequency A mode, the
input signal connects to the high impedance
CHANNEL A input jack and can be conditioned with
the LEVEL, SLOPE, and ATTEN controls. In the Fre¬
quency C modes, the input signal is connected to the
INPUT C jack (50 ohm). The signal is not conditioned
by any front-panel controls but may be counted either
directly (50 MHz) or by prescaling (550 MHz),
depending on the setting of the INPUT C switch.
The G channel of the 5326A model counts the signal
directly.
3-9. Period Modes
3-10. The period and period average modes allow
single period measurements or multiple period
averages to be made with input frequencies into
CHANNEL A of up to 10 MHz. These modes are use¬
ful for making low frequency measurements where
maximum resolution is desired.
3-11. For single period measurements, the MULTI¬
PLIER switch scales the time base frequency and
selects the placement of the decimal point and deter¬
mines the resolution of the measurement.
3-12. The period average mode is used for increased
resolution and reduced inaccuracies. For example, if
10 2 period averaging is selected, the counter will dis¬
play the average of 100 periods with the proper decimal
point. In this example, trigger error is 100 times less
than in a single period measurement.
3-13. Time Interval Modes
3-14. Two modes of time interval measurements can
be selected: time interval and time interval average.
The time interval modes measure the time between
points on a single waveform or between separate in¬
put signals; thus, pulse width and phase differences
can be measured. Separate slope and level controls
allow variable triggering levels on either the + or -
slope. Marker A and B outputs are available at
the rear panel to intensity-modulate an HP I BOA
oscilloscope. The markers indicate the trigger point
of the counter’s input circuits and provide a visual
means of adjusting the trigger points to measure
the time interval between any two points and are
useful to about 100 kHz.
3-15. In time interval measurements, Channel A
opens the main gate and Channel B closes the main
gate. While the main gate is open, the internal oscil¬
lator, divided by the setting of the MULTIPLIER
switch, is totalized by the counter and readout on the
display. The less the division factor, the more pulses
of the internal oscillator there are to count and, there¬
fore, the better the resolution and accuracy.
3-16. With time interval average, the main gate is
open for the number of time intervals selected by the
MULTIPLIER switch. The internal oscillator pulses
(not divided) are totalized only during the individual
time intervals. Once Channel B triggers, there must
3-1

Model 5326/27A
Operation
be a time lapse of 150 ns before Channel A can trigger.
Averaging of time intervals results in increased re¬
solutions and reduced inaccuracies. For a further
explanation of theory, refer to Paragraph 4-27.
3-17. Retio
3-1,8. The counter may be used to measure the ratio
of two signals in either the frequency or period mode.
By setting the rear-panel CSC I NT EXT switch to EXT,
the counter will accept an external signal (F ex t) for
use as the internal oscillator. This frequency should
be 100 Hz to 10 MHz at 1 V rms minimum to 5 V peak
maximum. A second signal (Fa), applied to either
INPUT A or C jack, is used as the comparator signal.
The MULTIPLIER switch controls the resolution of
the display. For a ratio of frequencies, the Ratio =
f A _ DISPLAYED NUMBER
F ex t MULTIPLIER SETTING'
(P), the Ratio =
For a ratio of periods
F A _ ?xt _ DISPLAYED NUMBER
P , F a MULTIPLIER SETTING
ext A
3-19. Disregard the unite and decimal point; also,
ignore any zeros to the left of the most significant
digit. It makes no difference which signal is higher
in frequency, as long as the two frequencies are with¬
in the specifications of their respective channels.
3-20. MARKER OUTPUTS
3-21. Two marker output jacks are mounted on the
counter’s rear panel. These outputs provide a
negative-going 2 ps pulse (approx.) at DTL levels each
time the input signal passes through the trigger point
of Channel A or B. The pulses may be used to trigger
other circuits or may be applied to the Z axis of an
HP 180 Oscilloscope. When using the pulses to
intensity modulate an oscilloscope, note that the
actual trigger point is the leading edge of the pulse.
The marker’s pulse width determines the upper fre¬
quency limit of the input signal. The pulses overlap
on the oscilloscope trace when the period of the signal
is less than the pulse width.
3-22. HYSTERESIS
3-23. Each input channel has a small amount of
hysteresis (about 100 mV). If the SLOPE switch is set
to “+,” the trigger pulse occurs at the top of the
hysteresis “window.” If the SLOPE switch is set to
the pulse occurs on the bottom line of the window.
In other words, the signal must pass through the entire
hysteresis window before a trigger pulse is generated.
3-2
3-24. When measuring frequency or period, the
counter positions the hysteresis band around zero (see
Figure 3-1). This assumes a waveform with no de
component and the counter's LEVEL control is in the
PRESET position. The input amplifier then yields
maximum input sensitivity for both positions of the
SLOPE switch. The offset introduces no measure¬
ment error, since the trigger point is repetitive from
cycle to cycle. The trigger point is point A for +
slope and point B for - slope.
Figure 3-1. Hysteresis Offset
3-26. In the time interval modes only, both input
amplifiers have an automatic compensation network
that keeps the trigger level at the same potential when
switching from positive to negative slope (see Figure
3-2). In this example, the window shifts upward to
accomplish this. There is the possibility, therefore,
that if Point A is near the top of the signal, switching
to negative slope will place a portion of the window
outside the signal (C). In such case, there would be no
triggering. When switching from time interval to
frequency, or vice versa, the trigger point shifts by
half the hysteresis band.
Figure 3-2. Hysteresis Compensation
3-27. ACCURACY
3-28. FREQUENCY MEASUREMENTS. The basic
counter accuracy is determined by two factors. One
factor is the aging rate of the 10 MHz crystal standard
in the time base (less than 3 parts in 10 7 per month).
A second factor is the inherent error of ± 1 count of the

display’s least significant digit, which is present in all
electronic counters. This error is due to phasing be¬
tween the timing pulse that operates the electronic
gate and the pulses that pass through the gate to the
counting assembly. The chart in Figure 3-3 shows the
error possible for frequency and period measurements.
3-29. The formula for determining the actual fre¬
quency is given as follows:
error = ± (-i-) ± E
fj x gate length (sec)
The expression j
^ X gate length (sec)
equals the ± 1 count ambiguity, where f| equals meas¬
ured frequency (Hz) and gate length equals the
selected gate time in seconds. E equals the time base
accuracy (monthly drift rate of the individual time
base times the number of months since calibration,
frequency change due to ambient temperature
change, absolute off-set at standardization, and line
voltage effects).
3-30. An example of frequency error calculation is as
follows:
f x = 3 MHz (3 X 10 6 Hz)
gate length = .1 sec (1 X 10' 1 )
E = 3 parts in 10 7 per month times 2 months
= 6 parts in 10 7
error =-*-
(3 X 10 6 ) (1 X 10- 1 ) 10 7
= 3.3 X 10- 6 ± 6 X lO" 7 = 3.9 X 10~ 6
or 3.9 parts in 10 c
Model 5326/27A
Operation
3-31. PERIOD MEASUREMENTS. There are three
factors contributing to the accuracy of period average
measurements:
a. T he aging rate of the 10 MHz crystal standard.
b. The ± 1 count ambiguity.
c. The trigger error for one period.
Assuming a signal-to-noise ratio of 40 dR, the
trigger error is less than 0.3% at rate sensi¬
tivity. A general formula for finding the per¬
centage error to be expected under various
conditions is as follows:
f
A =100 (± 2_± —§—± E)
nf n
A = Accuracy in percent
f^ = Time base frequency counted
fg = Frequency of input signal (Hz)
n = Number of periods averaged
e = 3 x 10 3 (trigger error for one period,
40 dB S/N at rated sensitivity.)
E = time base accuracy (monthy drift
rate of individual time base times the
number of months since calibration,
absolute value of off-set at standard¬
ization, frequency change due to
ambient temperature change, and
line voltage effects). A plot of the
above formula is shown in Figure 3-3.
3-3

Model 5326/27A
Operation
ERROR IN MEASUREMENT FREQUENCY MEASUREMENT
±1 COUNT
TIME BASE ACCURACY
PERCENTAGE 10' *
I
FRACTION
1
f
t
▼
±1/10°
10% 1X10 -1
±1/10
1% X o
1
w
± i/io 2
0.1% 1X10 -3
±1/10 3
0.01% 1X10" 4
±1/10 4
0.001%
1X10~ 5
±1/1G S
0.0001%
1X10" 6 ±1/10 6
0.00001%
1X10" 7
±1/10 7
0.000001%
00
1 o X
±1/10 8
0.0000001%
1X10" 9
±1/10 9
0.00000001%
1X10' 10 ±1/10 10
0.000000001%
1X10'"
± 1 / 10 "
< i 3 PARTS IN 10 , ASSUMED)
10 100 IK 10K 100K 1M 10M 100M 1C
PERIOD AVERAGE MEASUREMENT
±1 COUNT
- TIME BASE ACCURACY
1TRIGGER ERROR = 0.3%/PERIOD
COUNTED FREQ. IS 10MHz
550MHz
ASSUMED TIME BASE
ACCURACY {< ±3X10 7 1
ACCURACY WHEN USING
INTERNAL OSCILLATOR
ACCURACY POSSIBLE WITH
EXTERNAL OSCILLATOR
(CESIUM BEAM STANDARD)
10 100 IK 10K 100K 1M 10M 100M 1G
MEASURED FREQUENCY(Hz)
NOTE
FOR 550MHZ INPUT (-MO) USE LINE TO RIGHT OF ACTUAL GATE
LENGTH TO DETERMINE ACCURACY OF MEASUREMENT. SINCE
± 1 COUNT ERROR REPRESENTS ±10 COUNTS OF INPUT SIGNAL
WHEN PRESCALING BY 10.

Model 5326/27A
Operation
1. SAMPLE RATE control. Applies primary
power. Works in conjunction with FAST/
NORM/HOLT) switch to control interval be¬
tween measurements.
a. FAST - Varies display time from <100
H s to >20 ms. STORAGE switch (rear
panel) must be ON to use this mode.
b. NORM - Varies display time from <
20 ms to >5 seconds.
c. HOLD - Holds display indefinitely.
2. RESET Switch. Resets display and internal
count to zero and starts new measurement.
3. INPUT C (5327A). 50-ohm input for 0 to 550
MHz frequency measurements. Has dc cou¬
pling (with INPUT C switch in + 10 position)
and sensitivity of 100 mV rms sine wave (300
mV peak-to-peak pulse). Maximum input is
±5 volts referenced to ground (DO NOT EX¬
CEED). Trigger level is zero volts. The input
is ac coupled with the INPUT C switch in
DIRECT position. The frequency range is 1
kHz to 50 MHz with a sensitivity of 5 mV.
INPUT C (5326A). 50-ohm input for 0 to 50
MHz frequency measurements. Has dc cou¬
pling and sensitivity of 5 mV rms sine wave.
Trigger level is zero volts. Maximum input is
±5 volts referenced to ground (DO NOT
EXCEED).
4. FUNCTION selector. Selects mode of oper¬
ation. Blue lettering matches corresponding
blue lettering on TIME BASE/MULTIPLIER
switch.
a. S TOP, START - Used for totalize
mode to manually open and close counter’s
main gate and to turn scaled output on and
off. Frequency input range is 0 to 10 MHz.
b. PERIOD AVG A - Sets counter to
measure period of signal applied to
CHANNEL A input. Use MULTIPLIER
switch to select number of periods to be
averaged. Input frequency range is 0 to
10 MHz.
c. T.l. AVG A to B - Sets counter to
measure average time interval, A to B.
Channel A starts interval and Channel B
stops the interval. Use MULTIPLIER
selector to set number of time intervals to be
averaged. Time interval input range is 150 ps
to 10 sec; there must be a 150 ns deadtime
between intervals.
d. T.L A to B - Sets counter to measure
time interval A to B. Channel A starts meas¬
urement and Channel B stops the measure¬
ment. T.l. input range is 0.1 ps to 10 9 sec.
The internal time base frequency is divided
by the setting of the MULTIPLIER switch and
totalized for subsequent display. The more
cycles of the oscillator frequency that are
counted during A to B time, the better the
resolution. There must be 150 ns deadtime
between Channel B and Channel A trigger
points.
e. PERIOD A - Sets counter to measure
a single period of the signal applied to
CHANNEL A input. Use MUTLIPLIER
switch to set counted internal oscillator fre¬
quency and therefore the desire resolution.
Frequency input range is 0 to 10 MHz.
f. F REQ A - Sets counter to measure
frequency applied to CHANNEL A input.
Use TIME BASE switch to set gate time and
resolution. Frequency input range is 0 to 50
MHz.

Model 5326/27A
Operation
Figure 3-4. Front Panel Controls and Indicators (Continued)
g. FREQ C - Similar to FREQ A, except
sets counter to measure frequency applied to
INPUT C jack. 50-ohm input impedance.
5 V rms/7.5 V peak maximum input. Fre¬
quency range is 0 to 550 MHz prescaled or
1 kHz to 50 kHz direct. For the 5326B, the
frequency range is 0 to 50 MHz. See
INPUT C.
5. T IME BASE ‘'MULTIPLIER switch. The
function of the switch changes with each
mode of operation:
a. TOTALIZE - Determines scaling
factor for input signal prior to counting.
b. PERIOD AVG A - Selects number of
periods to be averaged.
c. T.I. AVG A to B - Selects number of
time intervals to be averaged.
d. T.I. A to B - Selects scaling factor for
internal oscillator signal.
e. PERIOD A - Selects scaling factor for
internal oscillator signal.
f. FREQ A and FREQ C - Sets gate time.
6. S LOPE switch. Permits triggering on positive
or negative slope of input signal.
7. A C-DC switch. Selects direct or capacitor
coupling for input signal. Minimum input
frequency on AC setting is 20 Hz.
8. A TTEN switch. Selects attenuation for input
signal. Used in conjunction with LEVEL
control to set input triggering point. Maxi¬
mum input: 250 V rms on all ranges except
25 V rms on XI range above 50 kHz. Recom¬
mended input is 0.1 V rms to 2 V rms times
ATTEN setting.
9. L EVEL control. Used in conjunction with
ATTEN switch to determine voltage at which
triggering occurs. With XI attenuator
setting, level is variable ±3 V; on X10, ±30 V;
and X100, ±300 V.
10. I nput jacks. Input jacks to Channels A and B.
Input impedance is l MR shunted by less than
25 pF. By using a 10 to 1 divider probe, input
impedance can be increased to 10 MG.
11. T rigger lamps adjacent to input jacks indicate
when amplifier triggering occurs.
12. C HK-SEP-COM-switch. (Check-separate-
common)
a. CHK - Connects internal 10 MHz time
base to Channels A and B circuitry to check
that unit is functioning. No indication in T.I.
or T.I. Avg; ignore displayed digits in period
average.
b. COM-SEP - Connects A and B inputs
in parallel when set to COM position. When
applying two separate inputs, set switch to
SEP. When set to COM, input impedance is
500 kQ shunted with less than 50 pF.
13. C (count) light. Lights when counter’s main
gate is open. For short-duration gate times,
the annunciator circuits include a 50 ms one-
shot MV to allow a visible flash of the C light.
14. * (asterisk). Indicates that proper units are
not displayed with combination of function/
time base selection. To interpret display, add
a zero to the right of least significant digit
displayed on the counter.