BK Precision 2165A, 2630, 2625, 2620A User Manual
INSTRUCTION
MANUAL
SPECTRUM ANALYZERS
MODELS
2165A
2620A
2625
2630
TEST INSTRUMENT SAFETY
Normal use of test equipment exposes you to a certain
amount of danger from electrical shock because testing
must sometimes be performed where exposed voltage is
present. An electrical shock causing 10 milliamps of
current to pass through the heart will stop most human
heartbeats. Voltage as low as 35 volts dc or ac rms should
be considered dangerous and hazardous since it can
produce a lethal current under certain conditions. Higher
voltages pose an even greater threat because such voltage
can more easily produce a lethal current. Your normal
work habits should include all accepted practices to
prevent contact with exposed high voltage, and to steer
current away from your heart in case of accidental contact
with a high voltage. You will significantly reduce the risk
factor if you know and observe the following safety
precautions:
5. Don’t expose high voltage needlessly. Remove
housings and covers only when necessary. Turn off
equipment while making test connections in highvoltage circuits. Discharge high-voltage capacitors
after removing power.
6. If possible, familiarize yourself with the equipment
being tested and the location of its high voltage
points. However, remember that high voltage may
appear at unexpected points in defective equipment.
7. Use an insulated floor material or a large, insulated
floor mat to stand on, and an insulated work surface
on which to place equipment; and make certain such
surfaces are not damp or wet.
8. Use the time proven “one hand in the pocket”
technique while handling an instrument probe. Be
particularly careful to avoid contacting a nearby
metal object that could provide a good ground return
path.
9. When testing ac powered equipment, remember that
ac line voltage is usually present on some power
input circuits such as the on-off switch, fuses, power
transformer, etc. any time the equipment is connected
to an ac outlet, even if the equipment is turned off.
1. Some equipment with a two-wire ac power cord,
including some with polarized power plugs, is the
“hot chassis” type. This includes most recent
television receivers and audio equipment. A plastic or
wooden cabinet insulates the chassis to protect the
customer. When the cabinet is removed for servicing,
a serious shock hazard exists if the chassis is touched.
Not only does this present a dangerous shock hazard,
but damage to test instruments or the equipment under
test may result from connecting the ground lead of
most test instruments to a “hot chassis”. To test “hot
chassis” equipment, always connect an isolation
transformer between the ac outlet and the equipment
under test. The B+K Precision Model TR-110
Isolation Transformer, or Model 1653A or 1655A AC
Power Supply is suitable for most applications. To be
on the safe side, treat all two-wire ac equipment as
“hot-chassis” unless you are sure it has an isolated
chassis or an earth ground chassis.
2. On test instruments or any equipment with a 3-wire ac
power plug, use only a 3-wire outlet. This is a safety
feature to keep the housing or other exposed elements
at earth ground.
3. B+K Precision products are not authorized for use in
any application involving direct contact between our
product and the human body, or for use as a critical
component in a life support device or system. Here,
“direct contact” refers to any connection from or to
our equipment via any cabling or switching means. A
“critical component” is any component of a life
support device or system whose failure to perform can
be reasonably expected to cause failure of that device
or system, or to affect its safety or effectiveness.
4. Never work alone. Someone should be nearby to
render aid if necessary. Training in CPR (cardiopulmonary resuscitation) first aid is highly
recommended.
2
Instruction Manual
for
Models
2615A, 2620A, 2625, 2630
SPECTRUM ANALYZERS
3
TABLE OF CONTENTS
TEST INSTRUMENT SAFETY .....Inside front cover
SPECIFICATIONS ....................................................5
OPTIONAL ACCESSORIES ....................................6
GENERAL INFORMATION.....................................7
Symbols ..................................................................7
Tilt handle................................................................7
Safety.......................................................................7
Operating Conditions................................................8
Maintenance.............................................................8
Selecting the Line Voltage........................................8
INTRODUCTION ......................................................9
General ....................................................................9
Operating Considerations .........................................9
CONTROLS AND INDICATORS...........................10
CALIBRATION.......................................................15
Vertical Calibration................................................15
Horizontal Calibration............................................15
Page
Page
INTRODUCTION TO SPECTRUM ANALYSIS....17
General .................................................................. 17
Types of Spectrum Analyzers................................. 17
Spectrum Analyzer Requirements........................... 18
Frequency Measurements ....................................... 18
Resolution.............................................................. 18
Sensitivity.............................................................. 19
Video Filtering.......................................................19
Spectrum Analyzer Sensitivity................................ 19
Frequency Response ............................................... 20
Tracking Generators............................................... 20
APPENDIX–dBm CONVERSION ..........................22
CUSTOMER SUPPORT..........................................23
INSTRUMENT REPAIR SERVICE ....................... 23
WARRANTY SERVICE INSTRUCTIONS............ 24
LIMITED ONE-YEAR WARRANTY..................... 25
4
Frequency
Input
SPECIFICATIONS
Frequency range:
0.15 MHz to 1050 MHz (–3 dB) (Models 2625 and 2630)
0.15 MHz to 500 MHz (–3 dB) (Models 2615A and
2620A)
Center frequency display accuracy: ±100 kHz
Marker accuracy: ±(0.1% span + 100 kHz)
Frequency display resolution: 100 kHz
(4½ digit LED for Models 2625 and 2630)
(4 digit LED for Models 2615A and 2620A)
Frequency scanwidth:
100 kHz/div. to 100 MHz/div. (Models 2625 and 2630)
in 1-2-5 steps and 0 Hz/div. (Zero Scan)
50 kHz/div. to 50 MHz/div. (Models 2615A and 2620A)
in 1-2-5 steps and 0 Hz/div. (Zero Scan)
Frequency scanwidth accuracy: ±10%
Frequency stability: Drift: <150 kHz / hour
IF-Bandwidth (–3 dB):
Resolution: 400 kHz and 20 kHz
(Models 2625 and 2630)
Resolution: 250 kHz and 20 kHz
(Models 2615A and 2620A)
Video-Filter on: 4 kHz
Sweep rate: 43 Hz
Amplitude
Amplitude range: –100 dBm to +13 dBm
Screen display range: 80 dB (10 dB / div.)
Reference level: –27 dBm to +13 dBm
(in 10 dB steps)
Reference level accuracy: ±2 dB
Average noise level:
–99 dBm (20 kHz BW) (Models 2625 and 2630)
–99 dBm (20 kHz BW) (Models 2615A and 2620A)
Distortion:
<–75 dBc; 2nd and 3rd harmonic
3rd order intermod.: –70 dBc
(two signals >3 MHz apart)
Sensitivity: dB above average noise level
Log scale fidelity: ±2 dB (without attn.) Ref.: 250 MHz
IF gain: 10 dB adjustment range
NOTE: Specifications and information are subject to change without notice. Please visit www.bkprecision.com for the most current product
information.
Input impedance: 50?
Input connector: BNC
Input attenuator: 0 to 40 dB (4 x 10 dB steps)
Input attenuator accuracy: ±1 dB/10 dB step
Max. input level: +10 dBm, ±25VDC (0 dB attenuation)
+20 dBm (40 dB attenuation)
Tracking Generator (Models 2620A and 2630
only)
Output level range: –50 dBm to +1 dBm
(in 10 dB steps and variable)
Output attenuator: 0 to 40 dB (4 x 10 dB steps)
Output attenuator accuracy: ±l dB
Output impedance: 50? (BNC)
Frequency range:
0.15 MHz to 1050 MHz (Model 2630)
0.1 MHz to 500 MHz (Model 2620A)
Frequency response: ±1.5 dB
Radio Frequency Interference (RFI): <20 dBc
General
Display: CRT, 6 inch, 8 x 10 div. internal graticule
Trace rotation: Adjustable on front panel
Output Probe Power: 6V
Line voltage: 115 / 230V ±10%, 50-60Hz
Power consumption: approx. 27W
Operating ambient temperature:
+10°C to +40°C
Protective system: Safety Class I (IEC 1010-1)
Weight:
Approx. 15.4 lb. (6 kg) (Models 2625 and 2630)
Approx. 13.2 lb. (5 kg) (Models 2615A and 2620A)
Dimensions:
4.9 in. (125 mm) H x 11.2 in. (285mm) W x 15 in. (380
mm) D.
Accessories Supplied
Power Cord
Instruction Manual
5
Near Field “Sniffer” Probe Set; Model PR
-
261
Antenna Kit; Model AN
-18
OPTIONAL ACCESSORIES
The PR-261 is the ideal tool kit for the investigation of
RF electromagnetic fields. It is indispensable for EMI
pre-compliance testing during product development, prior
to third party testing. The set includes three hand-held
probes with a built-in pre-amplifier covering the
frequency range from 10 kHz to 1000 MHz. The set
includes one magnetic field probe, one electric field probe
and one high impedance probe. All have high sensitivity
and are matched to the 50? inputs of spectrum analyzers.
The power can be supplied either from the batteries or
through a power cord directly connected to a B+K
Precision Models 2615A, 2620A, 2625 and 2630. Signal
feed is via a 1.5 meter BNC-cable. When used in conjunction with a spectrum analyzer, the probes can be used to
locate and qualify EMI sources. They are especially suited
to locate emission “hot spots” on PCBs and cables, as
well as evaluate EMC problems at the breadboard and
prototype level. They enable the user to evaluate radiated
fields and perform shield effectivity comparisons.
Mechanical screening performance and immunity tests on
cables and components are easily performed. Faulty
components and poor bonding locations can be isolated.
The magnetic probe incorporates a high degree of
rejection of both stray and direct electric fields, and
provides far greater repeatability than with conventional
field probes. Measurements can be made on the very near
field area that is close to components or radiation sources.
The electric field (monopole) probe has the highest
sensitivity of all three probes. It can be used to check
screening and perform pre-compliance testing on a
comparative basis. The high impedance probe is used to
measure directly on the components under test or at the
conductive trace of a PC board. It has an input
capacitance of only 2 pF and supplies virtually no
electrical charge to the device under test.
Probe Set Specifications
All probes are electrically shielded and are supplied in a
carrying case.
Frequency range: 100 kHz–1,2GHz
Power supply: 6V from Spectrum Analyzers or Batteries
Operating current: 10-15 mA
Probe dimensions: 40 x 19 x 195 mm (approx.)
Broad band antenna is useful for radiated signal
measurement.
Deluxe Carrying Case; Model LC-210
Rugged cordura carrying case is foam padded for
instrument protection, has zipped pockets for manual and
accessories, and includes web hand strap and shoulder
strap.
Viewing Hood; Model VH-26
Shades CRT to block ambient light and improve
definition of the display.
50-ohm to 75-ohm Matching Network;
Model ZTF-1
Most RF networks (except cable TV) have an impedance
of 50 ohms. The spectrum analyzers also have a 50 ohm
input impedance, which allows direct connection. Cable
TV networks have an impedance of 75 ohms. To use the
spectrum analyzer with 75 ohm networks, Model ZTF-1
will match the 75 ohm network to the 50 ohm input
impedance of the spectrum analyzer.
50-ohm Feedthru Termination; Model TE-26
The output levels of the tracking generator of the Models
2620 and 2630 are correct only when terminated into 50
ohms. The Model TE-26 provides a 50 ohm termination
and a BNC feedthru connection so that the tracking
generator output may be fed into high impedance circuit
at a calibrated level.
Rack Mount Adapter; Model RM-26
Model RM-26 mounts the spectrum analyzer to standard
19-inch racks.
6
GENERAL INFORMATION
The Models 2615A, 2620A, 2625, and 2630 spectrum analyzers are 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.
Symbols
ATTENTION - refer to manual
Danger - High voltage
Protective ground (earth) terminal
Tilt handle
To view the screen from the best angle, there are three
different positions (C, D, E) for setting up the instrument
(see Figure 1). If the instrument is set down on the floor
after being carried, the handle automatically 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 Spectrum Analyzer (C). For
the D position (10° inclination), the handle should he 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.
Safety
This instrument has been designed and tested in accordance
with IEC Publication 1010-1, Safety requirements for elec-
trical equipment for measurement, control, and laboratory
use. The CENELEC regulations EN 61010-1 correspond to
this standard. It has left the factory in a safe 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 Spectrum Analyzer in a safe
condition.
Fig. 1. Tilt Handle Operation
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 in a 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, neutral) of the instrument have been
tested against insulation breakdown with 2200V DC. Under
certain conditions, 50 Hz or 60 Hz 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:
• shows visible damage
• fails to perform the intended measurements
7
•
Selecting the Line Voltage
GENERAL INFORMATION
has been subjected to prolonged storage under
unfavorable conditions (e.g. in the open or in moist
environments)
• has been subjected to severe transport stress (e.g. in
poor packaging).
Operating Conditions
The instrument has been designed for indoor use. The
permissible ambient temperature range during operation is
+10°C (+50°F) to +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 (+14°F) to +70°C (+158°F).
The maximum operating altitude is up to 2200m. 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.
instrument extremely cold) 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 60 minutes at an ambient
temperature between +15°C (+59°F) and +30°C (+86°F).
Values without tolerances are typical for an average
instrument.
Maintenance
Various important properties of the spectrum analyzer
should be carefully checked at certain intervals. Only in this
way it is 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 aluminum parts, can be
removed with a moistened cloth (99% water + 1% mild
detergent). Spirit or washing benzene (petroleum ether) can
be used to remove greasy dirt.
The screen may be cleaned with water or washing benzene
(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.
The spectrum analyzer operates at 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 Fuse Type )
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 a small screwdriver (see Figure 2).
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 is
not permissible; B+K Precision 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
Line voltage 115V~ ±10%: Fuse rating: T 315mA
Line voltage 230V~ ±10%: Fuse rating: T 160mA
Fig. 2. Fuse Replacement
8
General
INTRODUCTION
The spectrum analyzer permits the detection of spectrum
components of electrical signals in the frequency range of 0.15
to 1050 MHz for Models 2625 and 2630 and 0.15 to 500 MHz
for Models 2615 and 2620. The detected signal and its content
have to be repetitive. In contrast to an oscilloscope operated in
Yt mode, where the amplitude is displayed on the time domain,
the spectrum analyzer displays amplitude on the frequency
domain (Yf). The individual spectrum components of “a signal”
become visible on a spectrum analyzer. The oscilloscope would
display the same signal as one resulting waveform.
Models 2625 and 2630
The spectrum analyzer works according to the triple superhet
receiver principle. The signal to be measured (fin = 0.15 MHz to
1050 MHz) is applied to the 1st mixer where it is mixed with
the signal of a variable voltage controlled oscillator (fLO 1350
MHz – 2350 MHz). This oscillator is called the lst LO (local
oscillator). The difference between the oscillator and the input
frequency (fLO – fin = 1st IF) is the first intermediate frequency,
which passes through a waveband filter tuned to a center frequency of 1350 MHz. It then enters an amplifier, and this is
followed by two additional mixing stages, oscillators and
amplifiers. The second IF is 29.875 MHz and the third is 2.75
MHz. In the third IF stage, the signal can be selectively
transferred through a filter with 400 kHz or 20 kHz 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.
Models 2615A and 2620A
The spectrum analyzer works according to the triple superhet
receiver principle. The signal to be measured (fin = 0.5 MHz to
500 MHz) is applied to the 1st mixer where it is mixed with the
signal of a variable voltage controlled oscillator (fLO 610 MHz –
1110 MHz). This oscillator is called the 1st LO (local
oscillator). The difference between the oscillator and the input
frequency (fLO – fin = 1st IF) is the first intermediate frequency,
which passes through a waveband filter tuned to a center
frequency of 609.5 MHz. It then enters an amplifier, and this is
followed by two additional mixing stages, oscillators and
amplifiers. The second IF is 29.5 MHz and the third is 2.9 MHz.
In the third IF stage, the signal can be selectively transferred
through a filter with 250 kHz or 20 kHz 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 1st LO. The spectrum analyzer scans a
frequency range depending on the ramp height. This span is
determined by the scanwidth setting. In ZERO SCAN mode
only the direct voltage controls the 1st LO.
Models 2620A and 2630 each include a tracking generator.
This generator provides sine wave voltages within the
frequency range of 0.1 to 1050 MHz for Model 2630 and 0.1
to 500 MHz for Model 2620A. 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 Considerations
It is very important to read Safety in the GENERAL
INFORMATION Section including the instructions prior to
operating the spectrum analyzer. No special knowledge is
necessary for the operation of the spectrum analyzer. The
straightforward front panel layout and the limitation to basic
functions guarantee efficient operation immediately. To
ensure optimum operation of the instrument, some basic
instructions need to be followed.
CAUTION
The most sensitive component of
the spectrum analyzer is the input
section. It consists of the signal
attenuator and the first mixer.
Without input attenuation, the
voltage at the input must not
exceed +10 dBm (0.7Vrms) AC or
±25 volt DC. With a maximum input
attenuation of 40 dB the AC voltage
must not exceed +20 dBm.
Exceeding these limits will
damage the input attenuator and/or
the first mixer.
Prior to examining unidentified signals, the presence of
unacceptable high voltages has to be checked. It is also
recommended to start measurements with the highest
possible attenuation and a maximum frequency range. The
user should also consider the possibility of excessively high
signal amplitudes outside the covered frequency range,
although not displayed (e.g. 1200 MHz). The frequency
range of 0 Hz to 150 kHz is not specified. Spectral lines
within this range would be displayed with incorrect
amplitude.
A particularly high intensity setting shall be avoided. 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 0 Hz. It is called IF-feedthrough. The line appears
when the 1st 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.
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