Wavetek 801 Service manual

Page 1

INSTRUCTION MANUAL

MODEL 801 50

MHz PULSE

THIS DOCUMENT CONTAINS INFORMATION PROPRIETARY TO WAVETEK. THE INFORMATION IN THIS DOCUMENT IS NOTTOBE USED FOR DUPLICATED

IN ANY MANNER WITHOUT THE PRIOR APPROVAL IN WRITING OF WAVETEK.

SAN DIEGO

9045Balboa Ave., P. 0.Box 651, SanDiego, California 92112 Tel 7

14/279-2200

San Diego,

Calif.

92123

TWX 9 1 o-335-2007

REV C .

Page 2

SECTION

GENERAL DESCRIPTION

1.1 THE MODEL 801

The Model 801 is a 50 MHz general purpose laboratory pulse generator. The instrument gives you full control in primary pulse triggering and shaping plus simultaneous TTL, ECL,

and sync pulses. The primary pulse output has controllability in offset and independent rise/fall durations, as well as pulse width, pulse delay and a choice of positive, negative or complementary outputs. The TTL, ECL and fixed levels and rise times that are standard for use with compatible devices. The primary pulse has minimum rise and fall times of 7 ns and a maximum of 250 ms.

The output is provides levels are fully adjustable through

External triggering can be set to any point of the rising or trailing edge of the trigger signal. Single pulses or pulse pairs may be triggered; pulse width may be trigger controlled;

continuous pulses may be gated and a precise number of pulses may be triggered for a ‘burst’ output. Manual and external triggering is indicated by an LED on the front panel for rapid visual set of trigger level.

volts with

volts into a

source impedance which

load. Upper and lower pulse

volts.

are of

double pulse controlled by delay control. Double pulse at all outputs except sync.

External Width: External signal at trigger input and trigger level control determine output pulse width and period as shown.

TRIGGER LEVEL WINDOW

TRIGGER LE

Trigger Burst:

time) for pulse burst (1 to 100 pulse range) as shown.

External trigger starts internal gate (delay

TRIGGER LEVEL

TRIGGER

1.2 SPECIFICATIONS

1.2.1 Five Simultaneous Pulse Outputs

Fixed level ECL,

with variable amplitude available over a 5 Hz to to 20 ns periods).

Operational Modes

Continuous: Generator frequency.

Triggered: Generator quiescent until triggered by external

signal or front control, then generates one pulse.

Gated: As triggered mode, except generator oscillates for the duration of the external signal.

Double

except

Versatility

TTL and sync pulses and a pulse

and variable rise/fall times. Pulses 50 MHz frequency range (200 ms

oscillates continuously at selected

Pulse: Continuous, trigger and gate, as above,

two pulses for

each period. Space between pulses of

‘DELAY TIME’ GATE

PULSE

BURST OUTPUT

1.2.2

Variable Amplitude Pulse

Upper and lower pulse levels are independently adjustable. Pulse dynamic range

mum. Into a maximum pulse 1OV p-p, minimum pulse

Overshoot and ringing is less than +100

Preshoot is less than

into

Pulse Outputs

termination, dynamic range is

mV) into 5Oa load.

into an open circuit from the

p-p mini-

0.5V

p-p.

of amplitude setting

+100

mV)

l-l

Page 3

Fixed (ECL, ECL, TTL) Pulses

Pulse levels for

ECL

ECL, ECL Transition Time: < 6 ns.

TTL

TTL Transition Time: < 10 ns.

loading as shown:

Sync Pulse

Sync pulse is 0 to at least

+1V

from a

-0.9V

source.

Delay

Pulse occurrence can be delayed from less than 10 ns to

100 ms with respect to the sync pulse. Maximum duty cycle is 70% for periods to 200 ns, decreasing to 30% for 20 ns periods.

Delay jitter is less than 0.1% plus 50 picoseconds.

Fixed delay is as shown:

TRIGGER LEVEL

TRIGGER INPUT

FIXED

Normal/Complement Control

Normal pulse or its complement is selected. The normally quiescent and active levels are reversed in complement format. This control affects all outputs except sync pulse.

1.2.3

Period range is from less than 20 ns to greater than 200 ms in 7 overlapping ranges.

Period jitter is less than 0.1% plus 50 picoseconds.

Time Domain

Width

Width range is from less than 10 ns to 100 ms in 7 overlapping ranges. Maximum duty cycle is 70% for periods to 200 ns, decreasing to 50% for 20 ns periods. Range switch also has a square wave detent

duty cycle is 50

50 +15% at 20 ns period.

Width jitter is less than 0.1% plus 50 picoseconds.

(

period changing to

1.2.4

SYNC PULSE

FIXED DELAY

VARIABLE AMPLITUDE

PULSE

Input Characteristics

~20

External Trigger

The external signal required to trigger the generator has a minimum amplitude of to mum amplitude of

Triggering is selected to occur at either rising or falling edge of trigger signal; triggering level is adjustable to be between

external and manual trigger occurrence accepted.

mV p-p to 50 MHz (from

Input impedance is approximately

22 pF

An LED lights for approximately 100 ms for each

1.2.5

General

mV p-p to 5 MHz increasing

source) and a maxi-

with a minimum width of 10 ns.

in parallel with

Sync pulse duty cycle is 50 period, changing to 50 trigger and external width modes, in which case it is determined by the trigger signal.

5% at 20 ns period except in

Transition Time

For variable amplitude pulse only. Independently adjustable leading and trailing edges from less than 7 ns (5 ns typical) to 250 ms in 7 overlapping decade ranges (measured from 10 to 90% points). Verniers give ranges except 5 ns, which gives 25: 1.

Linearity: 10 to 90% points on pulse.

l-2

For transition greater than 10 ns

50:1

adjustment on all

Environmental

Specifications apply at 25°C

Instrument will operate from 0°C to 50°C.

after 1 hour warm-up.

Dimensions

28.8

cm (11.4 in.) wide; 17.3 cm (6.8 in.) high; 29 cm

(11.4

in.) deep.

Weight

5.4

kg (12 lb) net; 7.3 kg (16 lb) shipping.

Power 90

to1 10V,108 to

50to400 Hz;

132V,

60 watts nominal.

to220Vor216

180

to250V;

Page 4

OPERATION

3.1

CONTROLS

The generator controls and connections are shown in figure 3-1 and keyed to the following descriptions.

MODE Switch

modes.

CONT - Continuous pulses at all output connectors.

TRIG

ger appears (see pulses occur,depending on mode and control settings.

GATE

trigger edge appears (see

occur until the trigger signal transverses the generator

trigger level again.

AND CONNECTORS

Selects one of the following eight

DC level at all outputs until a suitable trig-

, );

DC level at all outputs until a suitable

then one or more

, );

then pulses

EXT WIDTH suitable trigger appears (see pulse occurs which has the duration of the trigger signal.

TRIG BURST suitable trigger appears (see gate time as determined by

CONT DBL - As for CONT except two pulses occur

for each pulse period. Time to second pulse is set by

TRIG DBL - As for TRIG except two pulses occur

in the one pulse period. Time to second pulse is set”

DC level at all outputs until a

, );

DC level at all outputs until a

, )

;

then a fixed number of pulses occur

and

then a

to trigger a

Figure 3-l . Controls and Connections

3-I

Page 5

SYNC PULSE

50% DUTY TIME

WHEN TRIGGERING

IS INTERNAL

UPPER

LEVEL

NORMAL

COMPLEMENT

PULSE AT

NORMAL

DOUBLE PULSE

PULSE

OUT

DELAY

LEADING EDGE

TRANSITION TIME

WIDTH

TRAILING EDGE

TRANSITION TIME

LOWER

-LEVEL

LOWER

-LEVEL UPPER LEVE&

TE:

Underline indicates a front panel con trolled parameter.

Figure 3-2. Pulse Parameters

3-2

Page 6

GATE DBL - As for GATE except two pulses occur

for each pulse period. Time to second pulse is set by

TRIGGER Switch- Selects one of three trigger

methods: manual, an external trigger signal’s rising edge or an external trigger signal’s falling edge. The

external trigger signal is applied at

ECL Connector-An output

logic level pulse whose occurence and duration are controllable. Levels are active.

OUTPUT Switch- Selects a normal pulse or its

complement which swaps the active and quiescent levels. Affects all outputs, except SYNC,

with an

-1.8V

emitter-coupled-

quiescent,

-0.9V

___ 0 4

LEVEL Control- Inner knob sets acceptance thresh-

old for trigger signal at

MAN TRIG Switch

tion that equals the time the switch is held down.

Output depends on the mode selected (see

TRIG Indicator

mately 100 ms for each trigger signal accepted.

PERIOD/RATE Switch- Selects one of seven ranges

of pulse period. Calibrated in seconds and hertz.

VARIABLE Control - Varies the pulse period within

the range selected by the outer knob. Clockwise increases the pulse period and decreases frequency.

DELAY Switch

pulse delay, time to second pulse of double pulses or length of burst, depending on mode setting. OFF position ensures minimum delay.

VARIABLE Control

the range selected by the outer knob. Clockwise increases the delay.

WIDTH

width or an approximate 50% duty cycle.

VARIABLE Control

the range selected by the outer knob except

Switch -

Supplies a trigger with a dura-

An LED which lights approxi-

Selects one of seven ranges of

Varies the delay time within

Selects one of seven ranges of pulse

Varies the pulse width within

ECL Connector- An output like the ECL out-

put reversed.

TTL Connector

sistor-logic level pulse whose occurence and duration

are controllable. Level is <

active into a 5Ost termination.

TRAILING EDGE Control - Varies the duration of

the set by 1 time. Full cw exceed upper value of the selected range. Trailing edge time is not part of WIDTH time.

4 SYNC

> 0.5V

when the generator is in a continuous mode (see

1 ). In other modes, width is determined by the

time between initial transition of the trigger signal through the trigger level to the trailing transition.

LEADING EDGE Control - Same as013 but

varies the duration of the leading edge of the

OUT pulse. Leading edge time is part of WIDTH time.

TRIG INPUT Connector - Accepts an external

signal to trigger the generator. Triggers on rising or

falling edge of input as determined by paragraph 1.2.3 for input specifications.

except active and quiescent levels are

An output with a transistor-tran-

0.4V

quiescent, >

OUT pulse trailing edge. Duration range is

Clockwise rotation increases edge

Connector- An output with a pulse of OV

into

termination and a square wave

2.4V

. See

LOWER LEVEL Control - Outer knob sets the

lower level of the varied from-20 to or -10 to mum pulse height is 20 volts open circuit.

UPPER LEVEL Control

level of the

identical to that stated for the lower level.

erator. Pulses from this output may be controlled in

level and transition time as well as frequency and width.

OUT

+10

volts into a 5052 termination. Maxi-

Connector

OUT pulse, which may be

+20

volts into an open circuit

Inner knob sets the upper

The main output of the gen-

TRANSITION TIME Switch - Selects one of seven

ranges for Actual durations within a range are set by and

POWER Switch -Pulse generator on/off switch.

NOTES ON OPERATION

3.2

Operational modes are described in paragraph 3.1 under the mode switch. The pulse itself may be shaped in width, leading and trailing edge transition times, upper level, lower level, frequency of occurrence (period) and delay with

OUT pulse rise and fall durations.

3-3

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respect to its sync pulse. These pulse parameters are shown in figure 3-2. Specific setups for each mode are given in paragraph 3.3.

3.2.1

White Marks

3.2.4

Only RG58U to the circuit under test. A

Output Terminations

cable should be used to connect the 801

2W load should be used at

the circuit end of the cable for maximum pulse fidelity.

When first becoming familiar with the 801, the white mark settings are handy. The white mark settings for the front panel switches will always give a 5k to 50

kHz

sync signal when power is on. The same settings will give 50% duty time, TTL, ECL, ECL and

OUT pulses; the LOWER LEVEL/UPPER LEVEL control may need adjusting to observe the

OUT on an oscilloscope. Once the output is observed, each control can be adjusted and observed until the desired result is obtained.

3.2.2

Pulse Width, Transition and Delay

Narrow duty cycle pulses require the NORMAL OUTPUT while greater than 70% duty cycle pulses require the COMP OUTPUT setting. Pulse width plus trailing edge time plus delay time settings should not exceed the period time. (See figure 3-2.) The sum of width, trailing edge and delay actually must be somewhat less than period time by an amount

that depends upon the period time selected. Therefore, when the sum of the desired width, trailing edge and delay time exceeds 70% of the period time, the pulse should be observed to make sure it is as desired.

The 50% duty time width setting

(

)

is meant to be used

in continuous mode. Other modes result in the following default conditions.

The and TTL outputs and

Thevenin loads should be used

on the ECL outputs.

3.2.5

Nonlinear and Reactive Loads

Both nonlinear and reactive loads will cause pulse distortion. Reactive loads driven with fast transitions cause voltage spikes that can damage the 801 output amplifier. If it is necessary to drive reactive loads directly, the instrument must be protected against these voltage spikes.

3.2.6

Duty Cycle

Always use the lowest range possible for both delay and width functions. This will reduce the recovery time of the one-shots and extend the maximum duty cycle of the 801 to its fullest capability.

3.2.7

Output Mixing

The outputs of two 801’s may be mixed using the following network.

MIXED OUTPUT

Mode Selected

TRIG CONT TRIG GATE

3.2.3

ECL

Figure 3-3 shows a

output

A triggered 10 ns pulse A continuous output of paired 10 ns pulses A triggered output of paired 10 ns pulses A gated output of paired 10 ns pulses

Termination

5.2/0volt

voltage arrangements.

801

ECL

3 FT RG58U COAX

Figure 3-3. ECL Termination

3-4

ECL termination. Similar

-5.2V

ECL CIRCUIT

OR EQUIVALENT

FROM

FIRST 801

OUTPUT

FROM

SECOND 801

OUTPUT

Maximum output from either generator is limited to 6 volts.

3.2.8

Precise Output Levels

Many times when testing a circuit it is desirable to lock the output of the generator at either the high or low level. A precise measurement of this level may then be obtained using a DVM.

The external width MODE to EXT WIDTH, TRIGGER to

mode is useful for this purpose.

and TRIGGER

Set the

LEVEL maximum cw. The output will now be locked to the

lower

level. Switching the trigger to

will lock it to

the upper level.

Page 8

The OUTPUT NORM/COMP switch could also be used to reverse the upper and lower levels as the trigger edge does, but some error could be introduced by the X-Y multiplier.

Control

Operation

MODE CONT

3.2.9

Rise Time Measurements

When measuring rise time in a linear device under test, the error induced by the rise time of the testing system must be considered. on an oscill

For exam

oscope,

‘801 =

pie, when 1 rise time

observed

observed scope

rving the 801 rise time

obse

scope

801

That is, the observed rise time must be corrected for by the

inherent oscilloscope rise time to determine the actual 801 rise time. Extending the method to include a circuit under test will determine circuit under test rise time:

observed

3.3

OPERATION

801

scope

c.u.t.

In the following descriptions of operation, observe the pulse on an oscilloscope. When the

desired, disregard leading and trailing edge adjustments.

(See figure 3-2 for pulse parameters.)

3.3.1

Continuous Pulses

Set the controls as follows for continuous pulse output.

Control

MODE

Operation

CONT

OUTPUT

COMP

PERIOD/RATE Set as desired. and Level Controls

WIDTH Set to desired lower level time (see

figure 3-4). The > 70% pulse will start

WIDTH time after SYNC leading edge

with DELAY OFF.

COMPLEMENT

Figure

Control

SYNC

3-4.

>70%

DUTY CYCLE

Greater Than 70% Duty Cycle Pulse

Operation

PULSE

Edge Controls Set as desired.

and DELAY

3.3.3

Triggered Pulses

Set up as in paragraph 3.3.1. If triggering with an external

signal, connect the trigger source to TRIG INPUT. Ensure

that the trigger rate is slower than the pulse rate.

Control

MODE

Operation

TRIG

TRIGGER Set as desired. (Observe TRIG indicator

to ensure triggering occurs.)

OUTPUT

NORM (or COMP if inverted pulse is

desired)

All Other Controls

Set as desired. DELAY is constrained to be less than PERIOD-(WIDTH

+TRAIL-

ING EDGE). If a large pulse WIDTH is desired but cannot be obtained, refer to paragraph 3.3.2.

3.3.2

Continuous Wide Duty Cycle Pulses

Follow this setup for pulses greater than those that can be obtained in paragraph 3.3.1. The “pulse” that appears to be positive going is referred to as the > 70% pulse.

3.3.4

Set up as in paragraph 3.3.1. If gating with an external

Gated Pulses

sig-

nal, connect the gate source to TRIG INPUT. Set the gate pulse width to allow the number of pulses desired. Reset the controls as follows.

Control Operation

MODE

GATE

TRIGGER Set as desired. (Observe TRIG indicator

to ensure triggering occurs.)

3-5

Page 9

3.3.5

Pulses With Width Controlled Externally

Control

Operation

Connect the trigger source to TRIG INPUT and set the controls as follows.

Control

MODE

TRIGGER

Operation

EXT WIDTH

Set as desired. (Observe TRIG indicator

to ensure triggering occurs.)

Edge Controls

Set as desired. and Output Controls

3.3.6

Triggered Burst of Pulses

In triggered burst mode, the trigger initiates a gate pulse, controlled by the DELAY control, which gates the output pulses. Set the controls as

Control

MODE

Operation

TRIG BURST

follows.

MODE

OUTPUT

CONT DBL

NORM

(or

COMP if inverted

pulse

desired)

WIDTH

DELAY

Set as desired.

Set for desired width between double pulses.

PERIOD/RATE

Set for sum of WIDTH +

DELAY +

time

desired between successive double pulses.

Edge Controls

Set as desired. and Level Controls

3.3.8

Triggered Double Pulses

Set up as in paragraph 3.3.7. If trigqering with an external signal, connect the trigger source to TRIG INPUT. Reset the controls as follows.

Control

Operation

TRIGGER

Set as desired. (Observe TRIG indicator to ensure triggering occurs.)

PERIOD,

Set as desired.

WIDTH, Edge

Controls and Output Controls

DELAY

Set to the total period time of the number of pulses desired in the burst.

TRIG INPUT

Set input trigger period to greater than the DELAY time.

NOTE

Trigger Period > Delay Time > Pulse Period

3.3.7

Continuous Double Pulses

For continuous double pulses, set the controls as follows.

MODE

Control

TRIGGER

TRIG DBL

Operation

Set as desired. (Observe TRIG

indicator

to ensure triggering occurs.)

3.3.9

Setup as in paragraph

Gated Double Pulses

3.3.7.

If gated with an external signal, connect the gate source to TRIG INPUT. Set the gate pulse width to allow the number of pulses desired. Reset the controls as follows.

Control

MODE

TRIGGER

Operation

GATE DBL

Set as desired. (Observe TRIG indicator to ensure triggering occurs.)

3-6