Hameg HM 5005 User manual

HMrAritEta
Instruments
MANUAL
Spectrum Analyzer
HM 5005 / 5006

Table of contents
sath
teenical
details
Spectrum
Analyzer
HM
5005
/
5006
Operating Instructions
General Information .........cccccccceesesseeeeeeenteneeeeenaes M 1
Use of tilt handle 0.0... ccceeceeeesnreeeeeeennes M 1
S31 2] 0 re M 1
Operating CONCITIONS ...... cee eceeeeeeeestteeeeeennes M 2
WAITAMY 0.2... cceccececsecccceeceeseeeceesenentnesereneeeenens M 2
Maintenance 0.0... cccccccccccsseeeceecsneeeeeesstteeeeesenaaes M 2
Switching over the mains / line voltage ............. M2
INtOCUCTION 0... cece cccecsncteeeceeeeeeeeeeseeecnteeetereeeeeeres M 3
Operating INStruCtiONns ........ccceeeeeeceeeeeeeteeeeees M 3
Elements of Operation ............:c:cceeeeeeeeeeereeeeeeees M 3
Vertical Calibration ...........ccccccccccceeeesenesceeseeeteees M5
Horizontal Calibration ..........cccccecceseeeeeeeeseteeeeeeenes M6
introduction to spectrum analySIS 0.00... eee M 6
Types of Spectrum AnalyZers ........ccccceeeeeeees M 7
Spectrum Analyzer Requirements
Frequency Measurements ............:.::::ceeeerrreereees M 7
RESOIUTION ......c ec ceceeeeeceeeceeesenrececeessneeeeeeetneeeeenenes M 8
SONSITIVILY oo... cccccccceeesesteceeescneeeeeesnaeeeeenenes M 8
Video Filtering ......... cc ceeeecceceeesseeeeesseeeeeseesenees M8
Spectrum Analyzer Sensitivity .........0::cccceeeeeeeeene M 8
Frequency Re@Sponse .............eecccceeeeseeeeeeeeeeeeees M9
Tracking Generators... ceceeceeeseesenteeeeeeeeeees M9
EMI applications using the Spectrum Analyzer .. M10
Front Panel Elements
Folder with Front View ...........cccccssssssesesessenees M11
Block Diagram ......2...::cccccccessessseseceeneceeseseneeneesssceees B 1
Subject to change without notice 2.95 - 5005/5006

Specifications
Frequency range: 0.5MHz to 500MHz (-3dB)
Center frequency display accuracy: +100kHz
Marker accuracy: +(0.1% span + 100kHz)
Frequency display resolution: 100kHz
(4 digit LED)
Frequency scanwidth: 50kHz/div. to 5OMHz/div. —
in 1-2-5 steps and OHz/div. (Zero Scan)
Frequency scanwidth accuracy: +10%
Frequency stability: Drift: <150kHz / hour
IF Bandwidth (—3dB):
Resolution: 250kHz and 12.5kHz
Video-Filter on: 4kHz
Sweep rate: 43Hz
Amplitude range: —-100dBm to +10dBm
Screen display range: 80dB (10dB / div.)
Reference level: -27dBm to +13dBm
(in 10dB steps)
Reference level accuracy: +2dB
Average noise level: -99dBm (12.5kHz RBW)
Second and third harmonic: <—75dBc Spectru m Ana lyzer H M5005 / H M5006
Third order intermod.: —70dBc
(two signals >3MHz apart) Frequency Range 0.5MHz - 500MHz.
Log scale fidelity: +2dB (without attn.) 250MHz 4 Digit Display (Center & Marker Frequency, 0.1MHz resolution)
mete 00S eleenent Tange ~100 to +13dBm Amplitude Range, 12.5kHz, 250kHz and Video-Filter
Bal) aes Mee Ane etal Tracking-Generator (HM5006 only):
Input
impedance:
50Q
Frequency
range:
0.1MHz
-
500MHz.
Input connector: BNC Output Voltage: +1dBm to —50dBm (50Q).
Input attenuator: 0 to 40 dB (4 x 10dB steps)
Input
attenuator
accuracy:
+1dB
The
HM5005/HM5006
Spectrum
Analyzer
is
the
ideal
instrument
for
Maximum input level: +10dBm, +25V,,. analyzing any kind of signal within the frequency range of 0.5 to 500MHz. Both
(with OdB attenuation) — models include a Scanwidth Selector that can adjust the frequency display
baectcieht width from 50kHz to 50 MHz per division. Narrow-band signals are easily
(with 40dB attenuation)
analyzed by this high resolution feature.
The analyzer can measure low amplitude signals and has a measurement
range of over 110dB. Including switchable attenuators, a range of -100dBm
to +13dBm can be measured with 80dB being displayed on the screen at 10dB/
Output level range: -50dBm to +1dBm division. In "Zero Scan Mode’ selective amplitude level measurements can be
| Sheen enon performed, while tuned to fixed frequency.
Output attenuator: 0 to 40dB (4 x 10dB steps) é eitie 4 .
Gein attenuator accuracy: +1dB Both models include a 4 digit numeric LED readout that can selectively
Output
impedance:
50Q
(BNC)
display
either
the
Center
or
Marker
Frequency.
Frequency
measurement
is
Frequency
range:
0.1MHz
to
500MHz
accomplished
by
adjusting
a
needle-like
cursor
to
the
point
of interest
on
the
Frequency
response:
+1.5dB
display
and
reading
the
4
digit
Marker
Frequency
value.
Hahn Fresendy Interference (Fn: <20dh6 The model HM5006 also includes a Tracking Generator that permits a four
terminal measurement that is useful in network and filter passband analysis.
The Tracking Generator is a frequency synchronous signal source with a range
Operating
temperature:
10°
to
50°C
of
100kHz
to
500MHz
that
is
controlled
by
the
frequency
of
the
spectrum
Display:
CRT.
6
inch,
8
x
10
div.
internal
graticule
analyzer.
The
output
level
is
adjustable
from
—50dBm
to
+1dBm
in
four
10dB
Trace
rotation:
Adjustable
on
front
panel
switchable
steps
in
addition
to
an
11dB
rotary
variable
attenuator
control.
mopped
Ralls
meee
50/60Hz
The
HM5005/5006
Spectrum
Analyzer
is
extremely
low-priced,
but
still
Protective
sytem:
Safety
Class
|
(IEC
1010-1)
|
quipped
to
meet
the
RF
measurement
needs
of
education
and
industry.
With
Weight:
approx.
7kg
this
user
friendly
instrument
HAMEG
out-performs
and
out-prices
its
Dimensions:
competitors
125mm (4.9°)H x 285mm (11.2°)W x 380mm (15")D
Lockable tilt handle
(19" rackmount optional}
Subject to change without notice

Symbols
J\ ATTENTION - refer to manual
A Danger - High voltage
pe Protective ground (earth) terminal
General Information
This spectrum analyzer is easy to operate. The logical
arrangement of the controls allows anyone to quickly
become familiar with the operation of the instrument,
however, experienced users are also advised to read
through these instructions so that all functions are
understood.
Immediately after unpacking, the instrument should be
checked for mechanical damage and loose parts in the
interior. If there is transport damage, the supplier must be
informed immediately. The instrument must then not be
put into operation.
Use of tilt handle
To view the screen from the best angle, there are three
different positions (C, D, E) for setting up the instrument. If
the instrument is set down on the floor after being carried,
the handle automaticaily remains in the upright carrying
position (A).
In order to place the instrument onto a horizontal surface,
the handle should be turned to the upper side of the
oscilloscope (C). For the D position (10° inclination), the
handle should be turned to the opposite direction of the
carrying position until it locks in place automatically
underneath the instrument. For the E position (20° inclination),
the handle should be pulled to release it from the D position
and swing backwards until it locks once more.
The handle may also be set to a position for horizontal
carrying by turning it to the upper side to lock in the B
position. At the same time, the instrument must be lifted,
because otherwise the handle will jump back.
A
o°
aa
ch
Safety
This instrument has been designed and tested in accor-
dance with JEC Publication 1010-1, Safety require-
ments for electrical equipment for measurement,
control, and laboratory use. The CENELEC regulations
EN 61010-1 correspond to this standard. It has left the
factory inasafe condition. This instruction manual contains
important information and warnings which have to be
followed by the user to ensure safe operation and to retain
the oscilloscope in a safe condition. The case, chassis and
all measuring terminals are connected to the protective
earth contact of the appliance inlet. The instrument
operates according to Safety Class I (three-conductor
power cord with protective earthing conductor and a plug
with earthing contact). The mains/line plug shall only be
inserted ina socket outlet provided with a protective earth
contact. The protective action must not be negated by the
use of an extension cord without a protective conductor.
The mains/line plug should be inserted before connections
are made to measuring circuits.
The grounded accessible metal parts (case, sockets,
jacks) and the mains/line supply contacts (line/live, neu-
tral) of the instrument have been tested against insulation
breakdown with 2200V DC.
Under certain conditions, 50Hz or GOHz hum voltages can
occur in the measuring circuit due to the interconnection
with other mains/line powered equipment or instruments.
This can be avoided by using an Isolation transformer
(Safety Class II) between the mains/line outlet and the
power plug of the device being investigated.
Most cathode-ray tubes develop X-rays. However, the
dose equivalent rate falls far below the maximum
permissible value of 36pA/kg (0.5mR/h).
Whenever it is likely that protection has been impaired,
the instrument shall be made inoperative and be secured
against any unintended operation. The protection is likely
to be impaired if, for example, the instrument
— shows visible damage,
— fails to perform the intended measurements,
~ has been subjected to prolonged storage under
unfavourable conditions (e.g. in the open or in moist
environments),
— has been subject to severe transport stress (e.g. in poor
packaging).
Subject to change without notice
M1 5005/5006

Operating conditions
The instrument has been designed for indoor use. The
permissible ambient temperature range during operation
is +10°C (+50°F) ... +40°C (+104°F). It may occasionally
be subjected to temperatures between +10°C (+50°F)
and -10°C (+14°F) without degrading its safety. The
permissible ambient temperature range for storage or
transportation is -40°C (-40°F) ... +70°C (+158°F).
The maximum operating altitude is up to 2200m (non-
operating 15000m). The maximum relative humidity is up
to 80%.
If condensed water exists in the instrument it should be
acclimatized before switching on. In some cases (e.g.
extremely cold spectrum analyzer) two hours should be
allowed before the instrument is put into operation. The
instrument should be kept in a clean and dry room and
must not be operated in explosive, corrosive, dusty, or
moist environments. The spectrum analyzer can be
operated in any position, but the convection cooling must
not be impaired. For continuous operation the instrument
should be used in the horizontal position, preferably tilted
upwards, resting on the tilt handle.
The specifications stating tolerances are only valid if
the instrument has warmed up for 30 minutes at an
ambient temperature between +15°C (+59°F) and
+30°C (+86°F). Values without tolerances are typical
for an average instrument.
Warranty
HAMEG warrants to its Customers that the products it
manufactures and sells will be free from defects in
materials and workmaship for a period of 2 years. This
warranty shall not apply to any defect, failure or damage
caused by improper use or inadequate maintenance and
care. HAMEG shall not obliged to provide service under
this warranty to repair damage resulting from attempts by
personnel other than HAMEG represantatives to install,
repair, service or modify these products.
In order to obtain service under this warranty, Customers
must contact and notify the distributor who has sold the
product.
Each instrument is subjected to a quality test with 10 hour
burn-in before leaving the production. Practically all early
failures are detected by this method. In the case of
shipments by post, rail or carrier it is recommended that
the original packing is carefully preserved. Transport
damages and damage due to gross negligence are not
covered by the guarantee.
In the case of a complaint, a label should be attached to
the housing of the instrument which describes briefly the
faults observed. If atthe same time the name and telephone
number (dialing code and telephone or direct number or
department designation) is stated for possible queries,
this helps towards speeding up the processing of guarantee
claims.
Maintenance
Various important properties of the spectrum analyzer
should be carefully checked at certain intervals. Only in
this way is it largely certain that all signals are displayed
with the accuracy on which the technical data are based..
The exterior of the instrument should be cleaned regularly
with a dusting brush. Dirt which is difficult to remove on
the casing and handle, the plastic and aluminium parts,
can be removed with a moistened cloth (99% water +1%
mild detergent). Spirit or washing benzine (petroleum
ether) can be used to remove greasy dirt. The screen may
be cleaned with water or washing benzine (but not with
spirit (alcohol) or solvents), it must then be wiped with a
dry clean lint-free cloth. Under no circumstances may the
cleaning fluid get into the instrument. The use of other
cleaning agents can attack the plastic and paint surfaces.
Switching over the mains / line voltage
The spectrum analyzer operates on mains/line voltages of
115V AC and 230V AC. The voltage selection switch is
located on the rear of the instrument and displays the
selected voltage. The correct voltage can be selected
using a small screwdriver.
Remove the power cable from the power connector prior
to making any changes to the voltage setting. The fuses
must also be replaced with the appropriate value (see
table below) prior to connecting the power cable. Both
fuses are externally accessible by removing the fuse
cover located above the 3-pole power connector.
The fuseholder can be released by pressing its plastic
retainers with the aid of asmall screwdriver. The retainers
are located on the right and left side of the holder and must
be pressed towards the center. The fuse(s) can then be
replaced and pressed in until locked on both sides.
Use of patched fuses or short-circuiting of the fuseholder
isnotpermissible; HAMEG assumes no liability whatsoever
for any damage caused as a result, and all warranty claims
become null and void.
Fuse type:
Size 5 x 20 mm; 250-Volt AC;
must meet IEC specification 127,
Sheet III (or DIN 41 662 or
DIN 41 571, sheet 3).
Time characteristic: time-lag
T315mA
Line voltage 230V~ +10%: Fuserating: T160mA
Line voltage 115V~ +10%: Fuse rating:
Subject to change without notice
M2 5005/5006

Introduction
Both instruments HM5005 and HM5006 are spectrum
analyzers. The HM5006 also contains a tracking generator.
The basic functionality of these two instruments is detailed
below.
The spectrum analyzer permits the detection of spectrum
components of electrical signals in the frequency range of
0.5 to 500MHz. The detected signal and its content(s)
have to be repetitive. In contrast to an oscilloscope
operated in Yt mode, where the amplitudes are displayed
onthe time axis, the spectrum analyzer displays amplitudes
on the frequency axis (Yf). The individual spectrum
components of “a signal” become visible on a spectrum
analyzer. The oscilloscope would display that signal as
one resulting waveform.
The spectrum analyzer works according to the triple
superhet receiver principle. The signal to be measured
(f,, = 0.5MHz to 500MhHz) is applied to the 1st mixer where
it is mixed with the signal of a variable voltage controlled
oscillator (f,, 610MHz- 1110MHz). This oscillator is called
the 1st LO (local oscillator). The difference between the
oscillator and the input frequency (f,, — f,, = 1st IF) is the
first intermediate frequency, which passes through a
waveband filter tuned to a center frequency of 609.5MHz.
It then enters an amplifier, and this is followed by two
additional mixing stages, oscillators and amplifiers. The
second IF is 29.5MHz and the third is 2.9MHz. In the third
IF stage, the signal can be selectively transferred through
a filter with 250kHz or 12.5kHz bandwidth before arriving
at an AM demodulator. The logarithmic output (video
signal) is transferred directly, or via a low pass filter to
another amplifier. This amplifier output is connected to
the Y deflection plates of the CRT.
The X deflection is performed with a ramp generator
voltage. This voltage can also be superimposed on a dc
voltage which allows for the control of 1*LO. The spectrum
analyzer scans a frequency range depending on the ramp
height. This span is determined by the scanwidth setting.
In ZERO SCAN made only the direct voltage controls the
1* LO.
The HM5006 also includes a tracking generator. This
generator generates sine wave voltages within the
frequency range of 0.1 to 500Mlz. The tracking generator
frequency is determined by the first oscillator (1st LO) of
the spectrum analyzer section. Spectrum analyzer and
tracking generator are frequency synchronized.
Operating Instructions
It is very important to read the paragraph “Safety”
including the instructions prior to operating the HM5005/
HM5006.
No special knowledge is necessary for the operation of
the HM5005/HM5006. The straightforward front panel
layout and the limitation to basic functions guarantee
efficient operation directly from switch on. Never theless,
to ensure the optimum operation of the instrument, some
basic instructions need to be followed.
The most sensitive component of the HM5005/HM5006
is the input section of the spectrum analyzer. It consists
of the signal attenuator and the fist mixer. Without input
attenuation, the voltage at the input must not exceed
+10dBm (0.7Vrms) AC or +25 volt DC. With a maximum
input attenuation of 40dB the AC voltage must not exceed
+20dBm. These limiting values must not be exceeded
or the input attenuator and/or the first mixer will be
destroyed.
Prior to examining unidentified signals, the presence of
unacceptable high voltages has to be checked. It is also
recommended to start measuring with the highest possible
attenuation and a maximum frequency range (500MHz).
The user should also consider the possibility of excessively
high signal amplitudes outside the covered frequency
range, although not displayed (e.g. GOOMHz).
The frequency range of OHz to 500kHz is not covered by
the HM5005/HM5006 spectrum analyzer. Spectrai lines
within this range would be displayed with incorrect
amplitude.
A particularly high intensity adjustment is not necessary
as “hidden” signals may be masked, the phosphor on the
CRT being loaded more where the noise is always
displayed. On the contrary, such signals will be harder to
detect due to the increasing beam width, even with
optimized focus setting. The way signals are displayed on
the spectrum analyzer typically allows for any signal to be
recognized easily, even with low intensity.
Due to the frequency conversion principle, a spectral line
is visible at OHz. This line appears when the 1% LO
frequency passes the IF amplifiers and filters. The level of
this spectral line is different in each instrument. A deviation
from the full screen does not indicate a malfunctioning
instrument.
Elements of Operation
The fold-out picture of the instrument's front plate after
these instructions, contains numbers referred to below:
The front plate is subdivided into three fields. Following
are detailed descriptions of the control functions located
on the top right next to the screen.
(1) POWER:
The power button with ON and OFF symbols.If power is
switched to ON position, noise will be visible on the
screen after approximately 10 seconds.
Subject to change without notice
M3 5005/5006

(2) INTENS:
This knob is used to adjust the intensity of the signal.
(3) FOCUS:
This control is for optimum sharpness adjustment.
(4) TR (Trace Rotation):
In spite of Mumetal-shielding of the CRT, effects of the
earth's magnetic field on the horizontal trace position
cannotbe completely avoided. Apotentiometer accessible
through an opening can be used for correction. Unimportant
pincushion distortions are unavoidable and cannot be
corrected.
(5) CF (CENTER FREQUENCY):
This LED is lit when the digital display shows the center
frequency. The center frequency is the frequency which
is displayed in the center (25) of the CRT X-axis.
(6) MK:
This LED is lit when the Marker pushbutton is in the ON
position. The digital display then shows the marker
frequency. The frequency of spectral lines not displayed
on a vertical graticule line can be determined by this
function.
(7) MARKER - ON/OFF:
If the MARKER pushbutton is set to the OFF position, the
CF indicator is lit and the display shows the center
frequency. When the switch is in the ON position, MK is
lit and the display shows the marker frequency. The
marker is shown on the screen as a vertical needle. The
marker frequency is adjustable with the MARKER knob
and can be aligned with a spectral line. Before any LEVEL
reading can be obtained, the marker must be switched
OFF.
(8) CENTER FREQ. - FINE:
Both rotary knobs are used for center frequency
determination.
The FINE adjustment function is self explanatory. The
center frequency is displayed at the horizontal center (25)
of the screen.
(9) UNCAL.:
The blinking of this LED signifies incorrectly displayed
amplitude values. This may occur when the scanned
frequency range (SCANWIDTH) is too large when
compared to the IF bandwidth (12.5kHz), and/or the video
filter bandwidth (4kHz). Measurements can then either be
taken without a filter (bandwidth, video), or the scanwidth
has to be decreased (scanwidth). The UNCAL. indicator
will also blink when the IF GAIN knob is not in the CAL.
position.
(10) BANDWIDTH:
Selects between 250kHz and 12.5kHz IF bandwidth. If a
bandwidth of 12.5kHzis selected, the noise level decreases
and the selectivity is improved. Spectral lines which are
relatively close together can be distinguished. As the
smail signal transient response requires a longer time this
causes incorrect amplitude values if the scanwidth is set
at too wide a frequency span. The UNCAL. indicator will
signify this condition.
(11} VIDEO FILTER:
The video filter may be used for noise reduction. It enables
smail level spectral lines to become visible which normally
would be within or just above the medium noise level. The
filter bandwidth is 4kHz. Again it has to be noted that
incorrect amplitude values will be displayed if the scanwidth
setting is too high and the video filter active (ON). Such
conditions are indicated by the UNCAL. LED.
Front plate bottom right section.
(12) INPUT:
The BNC 50Q input of the spectrum analyzer. Without
input attenuation the maximum permissible input voltages
of +25V DC and +10dBm AC must not be exceeded. With
the maximum input attenuation of 40dB the maximum
input voltage is +20dBm.
The maximum dynamic range of the instrument is 70cB.
Higher input voltages exceeding the reference leve! cause
signal compression and intermodulation. Those effects
will lead to erroneous displays. If the input level exceeds
the reference level, the input level attenuation must be
increased.
(13) ATTN.:
The Input Attenuator consists of four equal 10dB
attenuators, reducing the signa! height before entering
the 1°* mixer. Each attenuator is active if the push button
is depressed.
The correlation of selected attenuation, reference level
and baseline level (noise level) is demonstrated on the
following chart:
The reference level is represented by the highest horizon-
tal graticule line (26). The lowest horizontal graticule line
indicates the baseline (24). The vertical graticule is
subdivided in 10dB steps.
As previously pointed out, the maximum permissible
input voltages may not be exceeded. This is extremely
important because itis possible that the spectrum analyzer
Subject to change without notice
M4 5005/5006

will only show a partial spectrum of currently applied
signals. Consequently, input signals might be applied with
excessive levels outside the displayed frequency range
leading to the destruction of the input attenuator and/or
the 1st mixing stage. Also refer to INPUT.
The highest attenuation (4 x 10dB) and the highest usable
frequency range (scanwidth setting 5S0MHz/DIV.) should be
selected prior to connecting any signal to the HM5005/
HM5006 input. This permits the detection of any spectral
lines which are within the maximum measurable and
displayable frequency range, if the center frequency is set
to 250MHz. If the baseline tends to move upwards when
the attenuation is decreased, it may indicate spectral lines
outside the maximum displayable frequency range (i.e.
600MHz) with excessive amplitude.
(14) IF-GAIN:
This knob allows for the continuous adjustment if the
intermediate frequency amplification (IF-GAIN). The
amplification is calibrated at full left position. it increases
to approx. 10dB when rotated to the right, however,
without being calibrated.
(15) SCANWIDTH:
The SCANWIDTH field contains indicators which highlight
the appropriate frequency range per graticule division. The
range can be increased in steps with the right hand button,
and decreased with the left. Switching is accomplished in
1-2-5 steps from 50kHz/div. to 5S0MHz/div.
The width of the scan range is displayed in MHz/div. and
refers to each horizontal division on the graticule. The
center frequency is indicated by the vertical graticule
line at the horizontal. If the center frequency and the
scanwidth setting are correct, the X axis has alength of
10 divisions. With scanwidth settings below 50MHz,
only a part of the total frequency range ts displayed in
expanded mode.
When the SCANWIDTH is set to 50MHz/div, if the center
frequency is set to 250MHz, the frequency extends to the
right by 50MHz per division, ending at 50OMHz
(250MHz+(5x50MHz)). The frequency decreases to the
left in the same way. In this case the left graticule edge
corresponds to OHz.
With these settings, a spectral line is visible which is
referred to as “Zero Frequency Point”. It is the 1** LO
(oscillator) which becomes visible when its frequency
passes the first IF filter. This occurs when the center
frequency is low relative to the scanwidth range selected.
The “Zero Frequency Point” is different in each instrument
and therefore cannot be used as areference level. Spectral
lines displayed left of the “Zero Frequency Point” are so
called image frequencies.
In the ZERO SCAN mode the spectrum analyzer operates
as areceiver with selectable bandwidth. The frequency is
selected via the CENTER FREQ. knob. Spectral line(s)
passing the IF filter cause a level display (selective voltmeter
function).
(16) TRACK.GEN. (HM5006 only):
The Tracking Generator is activated if the push
button is depressed (ON). In this case, a sine signal
can be obtained from the OUTPUT BNC socket with
a frequency determined by the spectrum analyzer. In
ZERO SCAN mode the center frequency appears at
the output.
(17) OUTPUT (HM5006 only):
50Q BNC socket of the tracking generator. The output
level can be determined from +1dBm to —50dBm.
(18) LEVEL (HM5006 only):
The output level of the Tracking Generator can be
continuously adjusted with this knob by 11dBm (-10dBm
to +1dBm).
(19) ATTN. (HM5006 only):
Output level attenuator with four 10dB attenuators which
allows the signal to be reduced prior to reaching the
OUTPUT socket.
All four attenuators are equal and can be activated by
depressing the respective push button. Therefore it is
immaterial which attenuators are used to reach e.g. a
20dB attenuation.
Section underneath the screen.
The following controls are located below the screen:
(20) Y-POS. (Y-position), (21) Y-AMPL. (Y-amplitude),
(22) X-AMPL. (X-amplitude) and (23) X-POS. (X-position).
IMPORTANT: These controls are designated for the
accuracy of amplitude and frequency and do not require
adjustment under normal circumstances. A very accurate
RF Generator (e.g. HAMEG HM8133) is essential for any
adjustments of these controls.
Vertical Calibration
Prior to calibration, ensure that all input attenuators (13)
are deactivated and that the IF-GAIN knob (14) is set to
CAL. position. The HM5005/5006 must be in operation for
at least 60 minutes prior the calibration. Switch VIDEO
FILTER (11) to OFF position, set BANDWIDTH (10) to
250kHz, and SCANWIDTH (15) to 2MHz/div.
Connect RF signal of -27dBm (10mV) to the spectrum
analyzer input (12). The frequency of this signal should be
between 2MHz and 250MHz. Set the center frequency to
the signal frequency.
Subject to change without notice
M5 5005/5006

A: A single spectral line (-27dBm) appears on the screen
if a sufficiently low-distortion signal source is present. The
spectral line maximum is now adjusted with the Y-POS.
control (20) and placed at the top graticule line (26) of the
screen. All input attenuators have to be deactivated.
B: Next, the generator signal must be switched back and
forth between —27dBm and -77dBm, and the Y-AMPL.
control (21) adjusted so that the spectral line peak changes
by 5 divisions in the vertical direction. If this results in a
change of the Y-position, the calibration outlined under A
has to be repeated.
The calibrations A and B have to be repeated until an ideal
adjustment is achieved.
Finally, the operation of the input attenuators (13) can be
tested at alevel of -27dBm. The spectral line visible on the
screen can be reduced in 4 steps of 10dB each by
activating the attenuators incorporated in the spectrum
analyzer. Each 10 dB step corresponds to one graticule
division on the screen. The tolerance may not exceed
+1dB in all attenuation positions.
Horizontal Calibration
Prior to calibration ensure that all input attenuators (13)
are deactivated and the IF-GAIN knob (14) is in CAL.
position. The HM5005/5006 must be in operation for at
least 60 minutes prior to calibration. The VIDEO FILTER
push button (11) must be in OFF position, the BAND-
WIDTH (10) set to 250kHz, and SCANWIDTH (15) set to
50MH2/div. After the center frequency is set to 250MHz,
agenerator signal must be applied to the input. The output
level should be between 40 and 50 dB above the noise.
C: Set generator frequency to 250MHz. Adjust the peak of
the 250MHz spectral line to the horizontal screen center
(25) using the X-POS. control (23).
D: Set the generator frequency to 50MHz. If the 50MHz
spectral line is not on the graticule line (27) it should be
aligned using the X-AMPL. control (22). Then the calibration
as described under C should be verified and corrected if
necessary.
The calibrations C and D should be repeated until optimum
adjustment is achieved.
Introduction to spectrum analysis
The analysis of electrical signals is a fundamental problem
for many engineers and scientists. Even if the immediate
problem is not electrical, the basic parameters of interest
are often changed into electrical signals by means of
transducers. Common transducers include accelerometers
and load cells in mechanical work, EEG electrodes and
blood pressure probes in biology and medicine, and pH
and conductivity probes in chemistry. The rewards for
transforming physical parameters to electrical signals are
great, as many instruments are available for the analysis
of electrical signals in the time and frequency domains.
The traditional way of observing electrical signals is to view
them in the time domain using an oscilloscope. The time
domain is used to recover relative timing and phase
information which is needed to characterize electric circuit
behavior. However, not all circuits can be uniquely
characterized from just time domain information. Circuit
elements suchas amplifiers, oscillators, mixers, modulators,
detectors and filters are best characterized by their frequency
response information. This frequency information is best
obtained by viewing electrical signals in the frequency
domain. To display the frequency domain requires a device
that can discriminate between frequencies while measuring
the power level at each. One instrument which displays the
frequency domain is the spectrum analyzer. It graphically
displays voltage or power as a function of frequency on a
CRT (cathode ray tube).
in the time domain, all frequency components of a signal
are seen summed together. In the frequency domain,
complex signals (i.e. signals composed of more than one
frequency) are separated into their frequency components,
and the power level at each frequency is displayed. The
frequency domain is a graphical representation of signal
amplitude as a function of frequency.
The frequency domain contains information not found in
the time domain and therefore, the spectrum analyzer has
certain advantages compared with an oscilloscope.
The analyzer is more sensitive to low level distortion than a
scope. Sine waves may look good in the time domain, but
in the frequency domain, harmonic distortion can be seen.
The sensitivity and wide dynamic range of the spectrum
analyzer is useful for measuring low-level modulation. It
can be used to measure AM, FM and pulsed RF. The
analyzer can be used to measure carrier frequency,
modulation frequency, modulation level, and modulation
distortion.
Frequency conversion devices can be easily characterized.
Such parameters as conversion loss, isolation, and
distortion are readily determined from the display.
The spectrum analyzer can be used to measure long and
short term stability. Parameters such as noise sidebands
on an oscillator, residual FM of a source and frequency
drift during warm-up can be measured using the spectrum
analyzers calibrated scans.
The swept frequency responses of a filter or amplifier are
examples of swept frequency measurements possible
with a spectrum analyzer. These measurements are
simplified by using a tracking generator.
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Types of Spectrum Analyzers
There are two basic types of spectrum analyzers, swept-
tuned and real-time analyzers. The swept-tuned analyzers
are tuned by electrically sweeping them over their
frequency range. Therefore, the frequency components
of a spectrum are sampled sequentially in time. This
enables periodic and random signals to be displayed, but
makes it impossible to display transient responses. Real-
time analyzers, on the other hand, simultaneously display
the amplitude of all signals in the frequency range of the
analyzer; hence the name real-time. This preserves the
time dependency between signals which permits phase
information to be displayed. Real-time analyzers are capable
of displaying transient responses as well as periodic and
random signals.
The swept-tuned analyzers are usually of the trf (tuned radio
frequency) or superheterodyne type. A trf analyzer consists
of a bandpass filter whose center frequency is tunable over
a desired frequency range, a detector to produce vertical
deflection ona CRT, anda horizontal scan generator used to
synchronize the tuned frequency to the CRT horizontal
deflection. It is a simple, inexpensive analyzer with wide
frequency coverage, but lacks resolution and sensitivity.
Because trf analyzers have a swept filter they are limited in
sweep width depending on the frequency range (usually
one decade or less). The resolution is determined by the
filter bandwidth, and since tunable filters dont usually have
constant bandwith, is dependent on frequency.
The most common type of spectrum analyzer differs from
the trf spectrum analyzers in that the spectrum is swept
through a fixed bandpass filter instead of sweeping the
filter through the spectrum.
The analyzer is basically a narrowband receiver which is
electronically tuned in frequency by applying a saw-tooth
voltage to the frequency control element of a voltage
tuned local oscillator. This same saw-tooth voltage is
simultaneously applied to the horizontal deflection plates
of the CRT. The output from the receiver is synchronously
applied to the vertical deflection plates of the CRT and a
plot of amplitude versus frequency is displayed.
The analyzer is tuned through its frequency range by
varying the voltage on the LO (local oscillator}. The LO
frequency is mixed with the input signal to produce an IF
(intermediate frequency) which can be detected and
displayed. When the frequency difference between the
input signal and the LO frequency is equal to the IF
frequency, then there is a response on the analyzer. The
advantages of the superheterodyne technique are
considerable. It obtains high sensitivity through the use of
IF amplifiers, and many decades in frequency can be
tuned. Also, the resolution can be varied by changing the
bandwidth of the IF filters. However, the superheterodyne
analyzer is not real-time and sweep rates must be
consistent with the IF filter time constant.
A peak at the left edge of the CRT is sometimes called the
“zero frequency indicator” or “local oscillator feedthrough”.
It occurs when the analyzer is tuned to zero frequency,
and the local oscillator passes directly through IF creating
a peak on the CRT even when no input signal is present.
(For zero frequency tuning, F, ,=F,,). This effectively limits
the lower tuning limit.
Spectrum Analyzer Requirements
To accurately display the frequency and amplitude of a
signal on a spectrum analyzer, the analyzer itself must be
properly calibrated. A spectrum analyzer properly designed
for accurate frequency and amplitude measurements has
to satisfy many requirements:
. Wide tuning range
. Wide frequency display range
. Stability
. Resolution
. Flat frequency response
. High sensitivity
. Low internal distortion
. Linear and Logarithmic display modes (voltage and dB)
OnN Oa frwWhd =
Frequency Measurements
The frequency scale can be scanned in three different
modes full, per division, and zero scan. The full scan mode
is used to locate signals because the widest frequency
ranges are displayed in this mode. (Not all spectrum
analyzers offer this mode).
The per division mode is used to zoom-in on a particular
signal. In per division, the center frequency of the display
is set by the Tuning control and the scale factor is set by
the Frequency Span or Scan Width control.
In the zero scan mode, the analyzer acts as a fixed-tuned
receiver with selectable bandwidths.
Absolute frequency measurements are usually made
from the spectrum analyzer tuning dial. Relative
frequency measurements require a linear frequency
scan. By measuring the relative separation of two
signals on the display, the frequency difference can be
determined.
It is important that the spectrum analyzer be more stable
than the signals being measured. The stability of the
analyzer depends on the frequency stability of its local
oscillators. Stability is usually characterized as either short
term or long term. Residual FM is a measure of the short
term stability which is usually specified in Hz peak-to-
peak. Short term stability is also characterized by noise
sidebands which are a measure of the analyzers spectral
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M7 5005/5006