B+K precision 2165A Скачать руководство пользователя страница 9

 

 

INTRODUCTION 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

General 

 
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 (f

in

 = 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 (f

LO

  1350 

MHz  –  2350 MHz). This oscillator is called the lst LO (local 
oscillator). The difference between the oscillator and the input 
frequency (f

LO

 – f

in

 = 1st IF) is the first intermediate frequency, 

which passes through a waveband filter tuned to a center fre-
quency 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 (f

in

 = 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 (f

LO

 610 MHz – 

1110 MHz). This oscillator is called the 1st LO (local 
oscillator). The difference between the oscillator and the input 
frequency (f

LO

 – f

in

 = 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 
10 dBm (0.7Vrms) AC or 
±25 volt DC. With a maximum input 
attenuation of 40 dB the AC voltage 
must not 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. 
 

Содержание 2165A

Страница 1: ...INSTRUCTION MANUAL SPECTRUM ANALYZERS MODELS 2165A 2620A 2625 2630 ...

Страница 2: ...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 6 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...

Страница 3: ...3 Instruction Manual for Models 2615A 2620A 2625 2630 SPECTRUM ANALYZERS ...

Страница 4: ...AND INDICATORS 10 CALIBRATION 15 Vertical Calibration 15 Horizontal Calibration 15 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 ...

Страница 5: ...ls 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 Input Input impedance 50Ω Input connector BNC Input attenuator 0 to 40 dB 4 x 10 dB steps Input attenuator accuracy 1 dB 10 dB step M...

Страница 6: ...o 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 el...

Страница 7: ... 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 warn ings which have to be followed by the user to ensure safe operation and to retain the Spectrum Analyzer in a safe condition The case chas...

Страница 8: ...ment 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 wipe...

Страница 9: ...rred 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 scanwidt...

Страница 10: ... to the IF bandwidth and or the video filter bandwidth Measurements in this case can either be taken without a video filter or the scanwidth has to be decreased 9 CENTER FREQUENCY Coarse Fine Both rotary knobs are used for center frequency setting The center frequency is displayed at the horizontal center of the screen 10 BANDWIDTH Selects the IF bandwidth When the switch is engaged the noise leve...

Страница 11: ...aticule line The lowest horizontal graticule line indicates the baseline The vertical graticule is subdivided in 10 dB steps As previously pointed out the maximum permissible input voltages may not be exceeded This is extremely important because it is possible that the spectrum analyzer will only show a partial spectrum of currently applied signals ...

Страница 12: ...lied 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 10 dB and the highest usable frequency range highest scanwidth setting should be selected prior to connecting any signal to the input ...

Страница 13: ...creased by means of the button and de creased by means of the button Switching is accomplished in 1 2 5 steps from 50 kHz div to 50 MHz 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 middle of the horizontal axis If the center frequency and the scanwidth setting are ...

Страница 14: ...on of buttons may be used to achieve the desired attenuation 22 OUTPUT 50Ω BNC output of the tracking generator 23 TRACK GEN The tracking generator is activated when this button is engaged When activated a sine signal can be obtained at the OUTPUT BNC connector at a frequency determined by the spectrum analyzer In ZERO SCAN mode the center frequency appears at the output 24 LEVEL This knob adjusts...

Страница 15: ... to the spectrum analyzer input 13 The frequency of this signal should be between 2 MHz and 250 MHz Set the center frequency to the signal frequency A A single spectral line 27 dBm appears on the screen The spectral line maximum is now adjusted with the Y POS control 12 and placed at the top graticule line of the screen All input attenuators switches have to be released B Next the generator signal...

Страница 16: ...frequency to 250 MHz Adjust the peak of the 250 MHz spectral line to the horizontal screen center using the X POS control 16 D Set the generator frequency to 50 MHz If the 50 MHz spectral line is not on the 2nd graticule line from left it should be aligned using the X AMPL control 17 Then the calibration as described under C should be verified and corrected if necessary The calibrations C and D sh...

Страница 17: ...e 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 a...

Страница 18: ...ty 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 purity Noise sidebands are specified in terms of dB down and Hz away from a carrier in a specific bandwidth Long term stability is ...

Страница 19: ... power average noise power The analyzer always measures signal plus noise Therefore when the input signal is equal to the internal noise level the signal will appear 3 dB above the noise When the signal power is added to the average noise power the power level on the CRT is doubled increased by 3 dB because the signal power average noise power The maximum input level to the spectrum analyzer is th...

Страница 20: ...tor is the spectrum analyzer lst LO The spectrum analyzer tracking generator system is used in two configurations open loop and closed loop In the open loop configuration unknown external signals are connected to the spectrum analyzer input and the tracking generator output is connected to a counter This configuration is used for making selective and sensitive precise measurement of frequency by t...

Страница 21: ...21 Introduction to Spectrum Analysis Fig 7 Block Diagram ...

Страница 22: ... 15 8 μV 7 40 100 100 mV 46 1 61 1122 μV 84 37 23 14 1 μV 8 39 99 89 1 mV 47 0 60 1000 μV 85 38 22 12 6 μV 9 38 98 79 4 mV 48 1 59 891 μV 86 39 21 11 2 μV 10 37 97 70 7 mV 49 2 58 794 μV 87 40 20 10 0 μV 11 36 96 63 1 mV 50 3 57 707 μV 88 41 19 8 91 μV 12 35 95 56 2 mV 51 4 56 631 μV 89 42 18 7 94 μV 13 34 94 50 1 mV 52 5 55 562 μV 90 43 17 7 07 μV 14 33 93 44 7 mV 53 6 54 501 μV 91 44 16 6 31 μV ...

Страница 23: ...or this service We maintain a network of B K PRECISION authorized service agencies for this purpose To use this service even if the instrument is no longer under warranty follow the instructions given in the WARRANTY SERVICE INSTRUCTIONS portion of this manual There is a nominal charge for instruments out of warranty Technical advice on the use of your instrument Technical advice on special applic...

Страница 24: ...bes connectors and accessories that you are using with the device Customers not on an open account must include payment in the form of a money order or credit card For the most current repair charges please refer to the service and support section on our website Return all merchandise to B K Precision Corp with pre paid shipping The flat rate repair charge for Non Warranty Service does not include...

Страница 25: ...form on our website www bkprecision com within fifteen 15 days of purchase Exclusions This warranty does not apply in the event of misuse or abuse of the product or as a result of unauthorized alterations or repairs The warranty is void if the serial number is altered defaced or removed B K Precision Corp shall not be liable for any consequential damages including without limitation damages result...

Страница 26: ...26 NOTES ...

Страница 27: ...27 ...

Страница 28: ...28 22820 Savi Ranch Parkway Yorba Linda CA 92887 v110409 Printed in China ...

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