HP bench briefs 1979 schematic
*'
*I
:I
'
Group
Dan
Bmun
Hewktt-Paekard,
As
a
microwave technician involved
in the repair and calibration of
Hewlett-Packard's microwave
equipment, there have been many
occasions when customers touring
Ws
repair center have asked me,
ures
IF
flatnew power, and group
delay." We
3710A
Analyzer System.
But this article
MLA,
MLA and that's measure group
delay. And what
synonymous with envelope delay,
phase delay, or differential phase.
Basically, they
thing. Same may argue that there
or 3790A Microwave Link
it's
about one finction of the
noes,
Delay
Mtn.
are
talking about an
is
not about the
is
group delay?
all
mean the same
but they
neering
lot of mathemat-
IEEE
tw
tive
of radian phase with respect
radian frequency, dcpldw.
to
the
phase delay for an ideal nondispersive delay device, but may differ greatly in actual devices where
is
there
quency characteristic."
The Telecommunication Transmis-
sion Handbook by Roger L. Freeman
defines group delay
delay distortion and goes on
that
phase ChaTaCteristics with respect
radian frequency characteristics.
And, since group delay
the incremental change in phase
caused by an incremental change in
*
angular frequency, where the increment approaches zero in both
cases, group delay
ripple
it's
GD
in
the phase vs. fre-
the derivative
is
d4
=
-
df
View
are
mini-
texts
refer
Dictionary
"the deriva-
It
is
equal
as
envelope
to
of
radian
is
defined
expressed
SERVICE
test
HP
It
is
to
to
say
to
as
as
INFORMATION
where d indicates the derivative
4
is
the angular phase
and f is
(radians/sec.).
and
d+
drb
which means that
phase) and
zero)
Actually, group delay
cal concept and in practice cannot
measured
measured, referring back
IEEE definition,
dian) phase and differential (radian)
frequency which, if measured correctly, can
mate
tions in delay
cies that causes the problems and
referred
What
Electromagnetic waves travel
186,000
space. Electrical signals, however,
do not travel this fast through communications channels. In fact, sig-
nals may travel over certain types of
circuits
second, and
the angular frequency
df
can
be
further defined
limit
A4
(change in frequency)
for
it
to
be
group delay.
at
all. What
be
assumed
group delay.
at
to
as
group delay distortion.
is
Delay Distortion?
miles per second in free
as
slowly
&.HPARWI~FCOM
will
rarely travel
c
newkn-p
as
(radians),
A+
(change in
is
a
is
is
differential
to
It
is
the varia-
different frequen-
15,000
miles
of;
as
theoreti-
be
actually
to
the
(ra-
approxi-
per
faster
FROM
is
HEWLETT-PACM~
MAYJULY
than about
A
telephone line
pass filter, particularly if
loading
tion. Multiplex systems uBe very
sharp
from
in a &io receiver serve the
The
dowing
passage through a communications
channel
Delay becomes a problem only when
it
interferes with the
receiver
In the
tion causes little inte
the ear
phase variations. Facsimile,
graph, and data signals, however,
are quite vulnerable to delay
distortion.
Usually, only relative delay
maximum range or difference in
delay values in
portance, since only the delay
ence
causes distortion in the received
signal.
delay experienced by signal elements
except where signals, or parh of
signal,
point to another over different
routes and must arrive
time.
100
behavet3
is
used
to
reduce attenua-
filters
another, and the tuned
to
separate one channel
lters and
uce delay.
down of a signal in
is
of little importance.
to
understand
case
of speech,
is
relatively
a
Absolute delay - the
-
is
usually not important
are
transmitted
i
channel
at
like
in
circuib
-
is
from
the
lam
a
same
filter-
tele-
-
of
differ-
total
one
same
its
the
im-
a
For example,
if
two tones, such
as
1200 and 2200 cycles per second, are
used to transmit binary data (shifting from one frequency to the other),
it
is
important that these two tones
experience approximately the same
transmission delay in going from
one end of the circuit to the other. If
the data is being transmitted
1000
bits per second, each bit will be
at
one millisecond long. If these trans-
1's
missions consist of alternate
O's,
the signal will be alternately
and
shifting between 1200 and 2200 cps.
The transmission propagation time
for those two tones between the two
a
ends of
siderably. For example,
given circuit can vary con-
60
miles of
loaded telephone cable may intro-
a
duce
6.1
delay to the 2200 cycle tone of
milliseconds
as
compared to
5.1
milliseconds for the 1200 cycle tone,
a
difference of 1 millisecond. If the
2200 cycle tone is transmitted
first
followed by the 1200 cycle tone (each
transmitted for
millisecond),
it
can
1
be seen that they will both be re-
at
ceived
one following the other. In
the same time, rather than
120
miles, they would be received in the
reverse order!
Delay Distortion At Higher
Frequencies
In high speed data transmission, the
problem of delay distortion becomes
as
more serious and troublesome
the
transmission rate increases. Data
bits usually originate
as
rectangular-shaped pulses which are
used to modulate
carrier
at
a
par-
a
ticular keying rate for transmission
a
over
communications circuit. The
pulses resulting from this modulation process are composed of many
frequencies whose amplitudes and
a
phases have
fixed relationship in
time. The energy of the fundamental
and harmonic frequencies are vectorially added together to form the envelope of the composite signal. If the
pulses are processed through circuit
components such
as
band-pass filters
or amplifiers, which because of reactive (imaginary) components within
the circuitry do not offer equal
transit time to all frequencies, the
is
signal shape (envelope)
distorted. As shown in Figure 2,
seriously
if
the third harmonic is delayed by
one-half cycle relative
to
the fundamental, the pulse shape is severely
distorted.
To demonstrate the effect shown in
Figure 2, try the following experiment:
-Connect two audio oscillators (e.g.,
HP
Model 3325A's) to the A and
B
inputs of an oscilloscope.
-Set
for x frequency
at
y
A
amplitude (the exact frequency
and amplitude are unimportant).
Set oscillator
B
for
3
times the frequency and one-third the
amplitude.
so
-Set up the oscillators
that they
are phase locked together with
zero phase shift between them
(Figure 2A).
-Now shift the third harmonic
cillator
one-half cycle
-If
Figure 2B were fed into
so
that it is delayed by
(180
degrees).
the two composites shown in
a
os-
speaker,
you would note a drastic difference
in sound even though the frequencies haven't changed.
Phase Shift
The phase and frequency
of
a
signal
are, by definition, inseparable. In
a
fact,
good definition of frequency
the rate of change
of
phase with re-
is
spect to time, or dgdt, where + is the
7~
phase shift (usually in radians;
180",
dians equal
one cycle) and
WWW.HPARCHIVE.COM
2 n radians equal
t
is time in seconds.
ra-
Thus,
phase of
through
required for
it
follows that the more the
a
signal is shifted in passing
a
channel, the more time is
it
to get through the
channel. Where phase shift
known, the phase delay of a single
frequency
is
delay (time) = phase shift (radians)
frequency (radians
per sec.)
This
is
usually expressed
6
t
=-
w
It
is
important to note that in practical systems, phase delay,
expressed above, is applicable
single, steady-state frequencies.
as
as
only to
In an ideal system, phase shift would
be linear and all signals passing
a
through such
system would be delayed equal amounts, regardless of
their frequency. Unfortunately,
a
phase shift in
is
channel
never linear. In a high
communication
quality system, the overall phase
shift characteristic may look like
that shown in Figure
3.
Measuring Group and Envelope
Delay
Whenever a complex signal (such
a
modulated or keyed carrier fre-
is
quency)
transmitted, the relation-
as
ship between frequency and phase
shift described above no longer holds
true unless the system is perfectly
distortion-free. Since phase shift is
always non-linear in actual systems,
some of the component frequencies
undergo more phase shift than other
frequency components.
is
d
phw
velorpe delay will
a,
result.
%he
more
en-
wdd
placement of
spgat
to
dent delay of the rnrzdulation envelope or envel-
me
frequency with re-
the other and m indepen-
d*.
Group
The method used in the
Microwave Link Analyzer
be
no
db
Delay
HP
(MLA)
require a band
succeseful transmission, both en-
velope
of delay
tance. Hewlett-Packard
relative delay (and ocher
ters) in microwave
tions with the HP
Mimwme Link
Audio data line
and
of
and
to the PLL
nal.
A41
of
frequencies for
group
delay
are
the forms
greatest
general impor-
measures
pm-
rdio
3710
to
CCITT
by
the
the
as
the reference sig-
internai voltage con-
StandanES
3770AK3770B
Phase
Figure
4.
371ON3790A MLA perform-
ing a group delay measurement.
MLA
uses
a
The
technique where the present frequency increment is measured and
compared to the previous
increment.
Lock
detector is a special
filter designed to
quencies
lw&r
sweep frequency
Loop
pass
than
low
pass
only fre-
10
Ht.
If
t
erence. In the
in
And since the phase and fre-
quency
distortion.
As
figure, the swept signal
of
shown
case
phase
a
signal are,
in
the
of the
per frequency.
accompanying
by
defini-
is
applied
MU,
CRT.
SWEPT
The key
-L
s
WWW.
to
the group delay
LPF
H
7-
PARCHIVE.COM
-
c
PHASE
SENSITIVE
DETECTOR
tion
'
-
at
all.
*
LOW
PASS
FILTER
DELAY
SIGNAL
I
Figure
used in making envelope delay
measurements with the 3770A/B
Analyzers. The transmitter part of
the instrument generates
signal that
with a reference signal and then
test
starts
fkequency range the instrument
capable of transmitting and steps up
to
ence signals are switch-selectable.
For example, 300
could
the reference. Delay is measured by
comparing the delay of the envelopes
recovered
frequencies
ence signal.
5
shows the basic principal
is
signal. The
out
at
the high end
be
the test range, and
at
each
to
a
carrier
alternately modulated
a
test
signal
the lowest end of the
start,
frequency
stop and refer-
Hz
to
3.4
kHz
is
lkHz
of
the various
the delay of the refer-
test
rapid attenuation of all frequencies
outside the desired band. Unfortunately, such rapid change in the
tenuation characteristic
also
accompanied by rapid changes
in the phase shift.
case
In the
delay, a network which would correct the phase shift characteristics of
the communications channel might
very well neutralize the desired attenuation of the filters responsible
for the delay. Special delay equalizers called elliptical all-pass filters
are
required
lem. Without getting into filter
theory, it will suffice
these filters are complex and their
component values are usually calcu-
by
lated
cations, these filter networks
generally contain several adjustable
components
response can be adjusted for flatness
of excessive relative
to
overcome this prob-
computer. In typical appli-
so
that the group delay
of
to
a
at-
filter
is
say that
while being observed on the CRT of
group delay detector.
Summary
In conclusion, there are several im-
to
portant points
delay
is
a
transit time phenomena.
Group delay distortion causes audio
distortion in communication links.
This cannot be eliminated, but it can
be compensated for by special filters.
Relative group delay can
ured by
phase lock loop and displayed
graphically on
distortion
urement, but
ment. The actual transit time of
signal through a communication
link
changes or fluctuations in the
transit
another expressed
distortion that
a
unique application of
is
is
not important.
time from one frequency
remember. Group
be
meas-
a
CRT. Group delay
not an absolute meas-
a
relative measure-
It
is
the
to
as
group delay
is
important.
a
a
a
0
Delay
Where amplitude response of
cuit
to
loss
the desired performance. In
system, the channel bandpass filters
which isolate individual channels
from each other are the principal
sources of delay distortion. These filters should have uniform amplitude
response within
frequencies, but must exhibit
Compensation Networks
a
cir-
is
unsatisfactory, a filter
introduce a controlled amount of
at
certain frequencies
a
desired band of
is
to
obtain
a
carrier
a
used
very
Dan Braun, who
technician at the
probably tell from the nature of the article, Dan's primary responsibilities are the repair
and calibration
Born and raised in the San Francisco Bay Area, Dan attended College of San Mate0
where he obtained his
school while serving 6 years in the Navy. Dan and his wifi, Frieda, live in San Jose,
California.
WWW.HPARCHIVE.COM
has
been with Hewlett-Packard 5 years, is an instrument service
HP
Customer Service Center in Mt. View, California. As you can
of
HP's
microwave test equipment.
AA
degree. He furthered his electronic background in Class
A
IS
b
A
Quick
Guide to Batteries
BATTERIES
.I
.-
(Editor‘s Note:
appeared in the Electronic Buyers’
News and
mission
of
The
following article
is
reproduced with per-
CMP
Publications Inc.)
Discharge rate
is
expressed in
ampere-hours or milliampere-hours.
is
This
the product of current measured in amperes or milliamperes and
the number of hours that the cell or
battery can supply or discharge that
and
water.
The negative electrode
the zinc case. The voltage per cell
1.5V.
Cell sizes range from
D and the lowest cost battery
9-V rectangular case
torized products.
amount of current. The abbrevia-
Even though the electrochemical
tions are
fabrication of the most commonly
used batteries has been known for
a
more than
century, new and im-
proved batteries are providing users
of
an even widening choice
characteristics for meeting different (Leclanche) dry cell used for
requirements. general-purpose applicatione such
operating
primary
until recently the choice of battery
power
flashlights and portable radio@.
Ahr
and
mAhr.
~~ed~~
was
limited
to
the carbon-zinc
as
Carbon-Zinc (Zinc-Chloride).
zinc-chloride or heavy-duty version
of the basic system provides about
50%
more life for the same
as
the Leclanche version. Construc-
is
tion
chloride
lyte. Cell voltage
similar except the ammonium
is
omitted from the electro-
is
Then the zinc-chloride versions of
this
COnSeqUently,
to define and explain many
day’s batteries and their differing while the alkaline-manganese so-called alkaline cell
characteristics.
The term battery applies
of products classed
secondary. Because their active materials are irreversibly consumed
during periods of usage, primary
batteries can’t
article attempts the cgI.bon-zinc sy-m
Of
to-
ficantly improved energy density,
dioxide system Provided
improvement,
to
a
as
primary and
range
-
for
torized
silver oxide met the need for com-
.
efflcient powering of transis-
circuitry. Mercuric oxide and
pact button cells for hearing aids,
calculators, cameras, and other spe-
be
recharged. How-
cial needs.
the latter being suited system, using the same mitive and
ever, recharging secondary batteries
reconstitutes their active materials
to
be
and permits them
reused many
times.
Strictly speaking,
sembly of
two
a
battery
is
an
as-
or more cells. The
cells, each made up of two dissimilar
Carbon-Zinc
ONE PIECE COVER
Tin
Plated Steel Polyelhylane coaled
ELECTRODE - Carbon Paperboard
VENT WASHER
Paprboard
ASPHALT SEAL Acetale CoaMd Label
WAX RING SEAL
Flashlight
(+)
-
electrodes, are in contact with an
electrolyte within a closed container.
is
The voltage output of the cell
a
function of the electrochemical properties of the electrodes and the electrolyte. For systems in common use
to
today, this ranges from 1.2
3.0
volts.
Carbon-Zinc (Leclanche).
cell
Every
portant
discharge
the
cell voltage are obtained by con-
necting cells in series
and battery has two im-
characteristics: voltage and
rate.
Voltage higher than
so
that their
voltages combine. For example,
12-volt battery would consist of
2-volt
cells
or eight 1.5-volt cells. In
six
the early days of tube-type radio,
a
there was
45-
and 90-volt batteries, each requir-
ing
a
large number
constant demand for
of
cells.
most common and lowest cost primary system for general purposes,
from toys and flashlights
torized radios and recorders,
carbon-zinc batteries and cells
at
account for
a
mary battery sales.
least half
The cell consists of
electrode and an electrolyte com-
of
posed
manganese dioxide, am-
monium chloride and zinc chloride
WWW.HPARCHIVE.COM
&e&
SUPPORT WASHER
JACKET
MIX
PASTE -Flour. Starch
CAN -Zinc
CUP
STAR
BOTTOM
si@-
a
further finement
Battery
-
Polyethylane coated
Kran
h
C.llulose
-
Manganese
Dioxide. etc
Arnrnonlurn Chloride.
Zinc Clorlde
-
Kran Paper
BOTTOM
Paperboard
(-)
Tin
Plated
SIW
Still the
to
transis-
of
the pri-
a
positive carbon
Allr&e Manganese DiolEide.
of
the basic carbon-zinc
negative electrodes.
potassium hydroxide
of zinc-chloride. Reportedly, these
cells and batteries offer
improvement in energy density over
the carbon-zinc system for about
twice the price.
This
adapted for use where reliability and
length of service offset the increased
cost. Case sizes are similar and cell
is
voltage
the same.
Mercuric Oxide Cells.
curic oxide cell has
cal capacity for
its
carbon-zinc or alkaline cells, provid-
1.35
volts
per
-
ing
mercuric oxide, the anode
the electrolyte
or
roxide
sodium hydroxide. This
cell.
is
system provides effective button-size
cells for watches and hearing aids,
to
be
but seems
losing ground
more effective silver-oxide systems.
Silver-Oxide Cells.
provide more
of
carbon zinc cells of an equivalent
than
twice the energy
size and offer more energy per unit
volume than mercuric oxide cells.
Available in two types, high drain
and low drain, the silver oxide
are
cathodes
paired
and the electrolytes
is
is
AAA
to
is
the
size
for transis-
The
case
size
1.5V.
alkaline
in place
a
twofold
is
better
The
is
a
further re-
Highly
is
US&
system
The mer-
a
higher
size than
The
electri-
either
cathode
is
zinc and
is
potassium hyd-
to
the
Silver oxide cells
to
ZiDC
anodes;
ara3
potassium
Silver-Oxide Watch Battery
anode
cap
L-
-
Calhode
Cell
Anode material
--:,;
material
enclosure
L
(
(2”)
Separator
(AgpO)
hydroxide or sodium hydroxide.
1.55
These button-sized
cells are in
wide demand for watches and hear-
ing aids.
Magnesium Cells
are primarily
used in military applications due to
their
ability to withstand extremes
in temperature and humidity and to
provide energy after years of stor-
age. A magnesium alloy
is
used for
the anode; magnesium bromide for
the electrolyte. Magnesium cells
1.8
provide
Zinc-Air
volts per cell.
Cells
are high-energy primary systems available commercially today for hearing aid and
as
watch use. They use oxygen
positive electrode, zinc
tive electrode and feature
as
an
the
the nega-
electrolyte of potassium hydroxide. Shelf
life is excellent because they are
only activated by removing the tape
a
from
The zinc
tiny hole, which admits air.
air
cell provides
1.5
volts
per cell.
Lithium Cells.
cell or battery applies to
The term lithium
a
number of
different electrochemical systems
1
as
to
the
capable of producing from
volts per cell, Lithium
is
used
negative electrode in all of them, but
the voltage and operating characteristics are determined by the
choice of cathode and electrolyte. All
of the systems employ highly reactive alkali metals prepared without
so
the use of water,
as
non-aqueous.
they are classed
At present, lithium systems in use or
under investigation are also classed
as
either solid or liquid. In the solid
4
Hermetic Seal
Glass
Seal
Terminal
Collector
Cathode
Lithium
,
Cell
systems, the cathode is a metal
halide, sulfide or oxide, and the electrolytes are lithium salts in organic
solvent. The liquid systems have
soluble reactants with catalytic materials (sulfur dioxide or thionyl
chloride). The electrolytes in the liquid units can be organic or inorganic.
Case
Lithium
Anode
Separator
a
The Type Used
in
HP
Calculators
Rechargeable Nicads
Nickel-cadmium
blamed for ear& failure when
batteries
are
often
in
fact, you have been abusing the
poor
things
ing
it.
your devica
need it
the charger with you; or you
&I
And true
will
the
most
&wig without matis-
to
go
Murphy’s
dead
law,
when you
and do not have
do
have the charger, but there’s no AC
power available.
To
demonstrate proper nicad use,
let‘s
look at
Hewlett-Packard calculators.
cells,
the
nicad
cek
USBd
by
These
aqrding to their manufac-
turer, should average approxi-
500
rnately
cles.
Sometimes your treatment of
these batteries may
pear to shorten
chargeldischarge cy-
their
shorten
useful life.
or
ap-
Of
course,
sive temperatures
shotten
uw
bateties can also affect their
performance.
TM
as follows:
ni-
the
CIJlator on
l@ml
fully on rechWW.
sults in imximum battery perfor-
mance. Actually most
use their calculators in this manner,
but rather in
between
subjecting
their life. But
the
calculatar
chargeldidarge cycle is
1)
on
the
h-r
battety
indm
two
extremes. Those
nicads
will
to exces-
guarantee to
the
way you
and
charge
fully charge the
recharger;
and
OWAJrs;
2)
Opeate
Until a low
3)
This
method
remove
the
Mame
people
the
broad spectrum
the
cab
re-
do not
two
extremes are excessively deep discharging and continual recharger
use.
Continual
Continual recharger
harm
the
c&uktor
of
if
different
discharge
If,
however, a battery is subjected
a
to
over a
Reuharger
the
calculator
recharger
the
battery
level
cyde,
is
USBd
aurd
Uae
use
does
or
batteries.
in a combina-
battery power,
is Cffmharged
each chargel
no
harm is done.
not
to
repetitive depth of discharge
period
of many months, a
phenomenon known as memory
may result. Memory is an apparent
tempomy
loss
of capacity.
To
il-
lustrate, suppose a calculator is
kept
on
the recharger continually,
except
day when it is used
power. Over
the
for a 5-minute period each
on
a
long
period
nickel-cadmium batteries
battery
of
thne,
begin
to “remember” the capacity they
If
a
WWW.
H
PARCHIVE.COM
Though lithium systems cost
-
than silver oxide -materials, their
manufacturing costs are higher.
They can replace mercury and silver
based systems where their voltages
are about equal, but the higher
lithium voltages may call for circuit
or. product redesign.
Lithium battery systems can present
potential safety hazards because of
their higher energy content, higher
reactivity and the unusual nature of
the materials involved. Most often,
as
they are seen
supplementing
rather than replacing silver oxide
systems. But lithium cells have the
highest watt hours per cubic inch
(Whr/in3) and their hermetically
a
sealed cells afford
of
cess
five years.
shelf life in ex-
Secondary Batteries
Lead-Acid Cell.
Storage batteries
made of multiple lead-acid cells are
the most widely used rechargeable
c
batteries.
less
The positive electrodes of lead-acid
cells are made of lead peroxide and
the negative electrodes are made of
sponge lead paste. The groups of
positive and negative plates are interleaved and spaced by separators.
The complete assembly is places in
an electrolyte of diluted sulfuric
is
acid. A storage battery
made up of
separate compartments or cells, each
its
with
own filler and vent plug.
The voltage of each cell is approxi-
2
mately
batteries use cells of
combinations of
volts. Actually, automobile
2.1
volts
so
the
6
cells provides
12.6
volts.
An interesting sidelight can be
shown when you compare high cost
vs low cost automobile batteries
within the same group (i.e. group
a
being
as
standard size of battery such
24F).
In general, the low cost bat-
tery will have fewer plates (less lead,
a
hence lower cost), and have
lower
ampere-hour rating than the high
cost battery. Once quick way to ver-
ify this is to weigh the two batteries.
Obviously, the battery with more
plates has more lead and therefore
weighs more.
It
also lasts longer
when you inadvertently leave your
lights on.
cranking power
starts.
It
also can provide more
for
cold morning
Of more interest to the electronics
industry for the continous power of
remote instrumentation sensors, TV
sets, medical instruments and truly
portable tools is the true sealed
lead-acid battery.
vented and
all
No
acid or vapor
is
evolved oxygen gas is
recombined with the plate mate-
rials. These batteries and cells
are
presently limited to lower watt-hour
ratings than the maintenance-free
batteries. Although some of the
cases are flashlight cell size, these
sealed lead-acid cells are not interchangeable with either carbon zinc
and alkaline cells.
There are
proprietary methods for making
a
number of different
sea-
led lead-acid cells. Some makers are
c
are expected to deliver each day,
and they then will deliver no more
than that amount. Memory is com-
pletely reversible by a few complete
charge/discharge cycles (from full
charge down to low level
indication).
Deep Discharge
The other extreme encountered is
excessive deep discharging of
batteries. This is potentially the
most damaging to nicad cells. In
most cases, the cause
when a battery is too deeply dis-
charged is an internal short. Nor-
mally a charged or partially-
charged cell has enough internal
energy to vaporize a short. How-
ever, when a cell has been
eply discharged, the cell does not
have enough internal energy to
clear or prevent a potential short.
The result is that with a number of
of
failure
too
de-
deep discharge cycles, the chances
of shorting increase. There are two
varieties of shorts possible
low-impedance and a highimpedance short. A low-impedance
shorted cell will not respond to any
level of recharging current.
high-impedance shorted cell can
recover under high charging cur-
rents
(2A
to 4A). However, the shelf
life of this cell is very short as it
actually discharges itself through its
own internal short. Consequently,
both low-impedance and highimpedance shorted cells are considered permanent failures. Another
type of failure associated with deep
discharge is called cell reversal. In
a multi-cell battery, deep discharge
will cause one cell to become
exhausted first, since cells cannot
be precisely matched in capacity.
The cell with remaining capacity
drives the exhausted cell into a reverse state of charge which is cell
-
a
A
reversal. This is a permanent failure, and the battery pack must be
replaced.
The problem of discharging your
battery too deeply does not always
disappear even when you have
been made aware of the situation.
A malfunctioning low-level detect
system could be the guilty culprit.
We won't discuss catastrophic cell
failure in the form of venting since it
is an easily recognizable problem
requiring battery replacement. Ex-
cessive temperature, excessive
overcharge, cell reversal, and mis-
use or abuse of nicads are all
causes of venting.
So
remember, to get an average of
500
charge/discharge cycles out of
your
HP
calculator Nicads, give it a
full charge, use it until all the decimal points light up, then give it
another full charge.
WWW.HPARCHIVE.COM
SPARE PARTS
KIT
.
L
using very thin, spirally wound positive apd negative plates, with the
liquid electrolyte contained in
separator. Other makers are using
gelled sulfuric acid electrolyte. All of
these cells, however, have safety
vents, usually resealable membranes, to prevent the cell from
exploding in the event of accidental
overcharge.
Nickel-Cadmium Cell.
cadmium cell can
many times and has almost constant
voltage during discharge. These
cells operate well
can
tures and
led.
be hermetically sea-
The nickel-
be
recharged
at
low tempera-
a
Recommended Spare
Lead-Acid Automobile Battery
Inter-wII
a
Connector
In the charged condition, the positive electrode
and the negative electrode
lic cadmium. The electrolyte
For
Vent Plug
\
\
HP
,-/
post
is
nickel hydroxide
Products
Negative
Strap
Partition
Separator
Negative
Plate
is
metal-
solution of potassium hydroxide. The
average operating voltage
1.2 volts.
Nickel-cadmium power sources are
divided into the low watt-hour units
suitable for calculators, walkietalkie portable radios and portable
tools, not
with higher ratings which are
widely used in aircraft ignition systems. Sealed nickel-cadmium cells
are made in button
range of flashlight
Rechargers are supplied with the
consumer product
is
a
cord transformer-rectifier assembly.
Parts
is
to
mention vented versions
sizes
through the
“D”
as
part of a line-
Kit
0
about
cells.
Spare
f
last issue
Th
showed you
dering parts directly from
for Mail Order Parts)
avoid the $20 minimum charge.
Now,
here
replenishing spare parts kits.
SPARES is the name of
program used by HP to generate recommended spare parts lists for most
HP products. After purchasing the
recommended spare parts kit, if your
instrument should ever need repair,
is
there
the part available. Probability
even higher if spares are replenished
as
they are used.
a
simple system for
is
a
way to put it
a 90% probability of having
Bench Briefs
or-
HP
(MOP
so
you could
to
use
-
a
computer
is
SPARES
Parts
Multiple Lists
Recommendations can
single product
quantity of identical products (96
each 5245L), or
for various quantities of different
products (6 each 412A, 27 each
1707A, and
mendations can be made for
parts inventory
nine years.
-
Anticipated Requirements
Evaluation System
be
made for
(1
each 5245L),
a
combination list
9
each 5245L). Recom-
a
spare
of
one year up to
Long-Term Packaging
Long-term and military-standard
a
a
packaging
used for long-term packaging
increases the kit’s shelf life because
each part
and marked. This provides easy
identification and protection against
destructive effects of weather and
atmospheric conditions while in
storage.
For more information about
SPARES, contact your local HP
Sales and Service office. Reference
the HP Corporate Parts Center
Policies and Procedures Manual,
Section
is
optional. The process
is
individually packaged
3080.
WWW.HPARCHIVE.COM
INTEGRATED CIRCUIT CROSS REFERENCE
Replacement Part
When selecting replacement parts
for your HP products, you may
notice that many manuals list only
an HP part number for the part,
it
even though
is
manufactured by one of the large
appears that
semiconductor manufacturers.
ice personnel often ask why only
this
part
Serv-
HP
part numbers are listed.
is
recommended that
It
ment parts
the
original
duct
will
parts
identical
chased
be
performance
be obtained. While some
used
in HP instruments are
to
that
at
a
used
which can
local electronics dis-
Hp
replace-
to
ensure that
of
the pro-
be
pur-
tributor, many times parts will be
selected for certain characteristics,
as
such
Numbu
gain, bandwidth, capaci-
Ymuhctum
tance, etc. There may also
mechanical differences, such
shaping or length of leads. In some
cases special quality checks are
employed
bility parts
and
Therefore, we suggest obtaining re-
placement parts from
tain the quality that you have paid
for
be
situations however where
placement parts
substituting parts
return the product
mediately.
worthwhile
will
HP
stalled
Cross
to
ensure
are
at
HP
field
in
your instrument.
In
these cases
to
see
used
offices.
are
Reference
be
slight
as
the
that
high relia-
at
the factory
HP
to
main-
There
not in stock and
will
allow you
to
service im-
if
a
substitute part
it
HP
may
may
re-
work in the circuit. Perhaps an
part could be ordered and in-
at
some later date.
Numkr
To
help you in these situations,
a
here’s
cross-reference of HP integrated circuit part numbers
ufacturers -generic
type”
bers (whom in most cases
originator
of
the part). Even though
the cross-reference only
manufacturer, there may actually
several approved sources for
part. While every attempt was made
to
ensure
is
advisable
the
accuracy of the
to
compare
tion of the device being replaced
with the description of the substi-
to
tuted part. For example,
be
ice manual describes the device
as
a
being replaced
flop”, check
this
“dual
against the descrip-
tion of the replacement part.
to
man-
part num-
is
lists
an
list,
the
descrip-
if
the
serv-
J-K
flip-
the
one
be
HP
it
OOO39
00350
00575
01590
01
698
01795
01876
01921
01 973
01991
02023
02037
02180
02237
02290
02569
02598
02634
02713
02763
02838
02882
02883
0291
03183
03285
Nippon Electric
Exar Integrated
westem
Digital
plessey
-
Texas
In&.
tnc.
synertek
HP
Div.
02
RCA
GE
Transitron Electronic
Illinois
Motorola Semiconductor Products
Precision
Fairchild Semiconductor
Raytheon
Cfystalonics,
Unitrode
sprague
General
Teledyne Semiconductor
Dynamic
Ze&x
siliconix
0
%-
HP
Analog
Santa Clara
Corp.
sdkl
Co.
Semiconductor
Tool
Works
MonoUthics
Co.
Corp.
Elect.
In&.
Measurements
Inc.
Sub.
Corp.
Div.
22
Data
Devices
Semiconductor Div. HQ
Div.
Corp.
Co.
Systms
Cup.
Co.
Inc.
Semioond.
State
Teledyne
of
Systems
Inc.
Cmpnt.
ICs
Div.
Prod. Dept.
Cup.
Inc.
Liwn
Inc.
Dw.
Semlcondudor
Semicon. Prod. GP
Corp.
Redcor
Corp.
86
Div.
Div.
Div.
Tokyo,
JP
Sunnyvale,
Newport
santaAna,CA
Dallas,
santa
santa
somenrib,
AM, NY
Wakefield,
Chicago,
Phoenix,
Santa Clara. CA
Mountain
Mountain
Cambridge, MA
watertown,
concord,
HrcksvHle, NY
Mountain
Wind\ester,
Cod,
Santa
Sunnyvale, CA
Cupertino, CA
Nonrvood,
CA
ha&,
TX
Clara
CA
Clara, CA
NJ
MA
IL
AZ
View,
VI.
MA
NH
View,
MA
CA
Clara, CA
MA
CA
CA
CA
CA
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Harris Semicon. Div. Hams-Intertype
Intel
Cop.
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Nltron
Sprague
Burr
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SGS
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Siemens
Data Delay Devices
Zilog
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Texas Instruments France
Hytek
Corp.
Semiconductor
philbridc
Inc.
Micro
Systems
Inc.
Systems
hays,
Cup.
Inc.
Inc.
Devices
Inc.
Corp.
Memories
Div. McDonnell
Electric
Co.
Co.
Elemonics
Corp.
Components
Microsystems
Semicon.
Corp.
Nexus
Inc.
Douglas
Corp.
Inc.
Inc.
Inc.
81
MC Div
Corp.
Group
SlatersviUe,
Santa Clara,
Dedham.
Colmar,
santn
CupetWl~, CA
Burlington,
Mountain
Santa
Sunnyvale, CA
Franldin Park,
Melbourne,
Mountain
carrollton,
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Tucson,
Milan,
Melville,
scowdale,
Clifton,
Cupertino, CA
Nice,
FR
San Diego. CA
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