Rohde & Schwarz SMK Service and user manual

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Operating manual

SIGNAL GENERATOR SMK

348.0010.02

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Contents of SMK Manual

VOLUME I

1. Data sheet
2. Preparation for Use and Operating Instructions
3. Maintenance Instructions

VOLUME II

4. Service Instructions for Complete Instrument
5. Service Instructions for the Individual PC Boards

FM Modulator Output Section Mixer 60-MHz Multiplier RF Oscillator 1 RF Oscillator 2 Interpolation Oscillator 1 MHz Interpolation Oscillator 1 kHz Interpolation Oscillator 1 Hz

VOLUME III

5. Service Instructions for Individual PC Boards

Reference Board Filter Motherboard 1 Motherboard 2 Modulation Control Microprocessor Keyboard Display Board Power Supply RF Attenuator Overvoltage Protection Option SMK-B3

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B&S-ADDRESSES

ROHDE&SCHWARZ

ROHDE & SCHWARZ GmbH & Co. KG Mühldorfstraße 15 · Postfach 801469 Tel. (089) *4129-1 +49 89 4129 1 · Telex 523703 (rus d)

Argentina Argentina Oton R. Klein S.A. P.O.B. 568

ROHDE&SCHWARZ (Australia) Pty. Ltd. Suministros Tecnicos Ltda. P.O.B. A 274 Sydney South, N.S.W. 2000 Guayaquil

Bangladesh Business International Ltd.

Brazil

Canada

Hanseatica Cia. Ltda Ap. Aéreo 14467 Bogotá D.E.1

Ethiopia

Great Britain

Hongkong Schmidt & Co. (H.K.) Ltd. G.P.O. Box 297

Japan Dipl.-Ing. Adolf Zihler Port P.O.B. 586

Luxembourg

ROHDE & SCHWARZ (Nigeria) Ltd. P.O.B. 2278

Pakistan Saddar-Karachi-0301

Feru Estemac Peruana S.A. Casilla Correo 224 Lima-18 (Miraflores) Tel. (–) 455530, Tx. 25385

Portugal

Neppel Hd. Singapore-0208 Tel. (-) 2211533 Tx 21297

South Africa

Herzogstraße 61 D-6078 Neu-Isenburg Tel. (0.61.02) 31.36. Tx, 4.185.641

Münchener Straße 342 D-8500 Nürnberg 50 Tel. (09 11) 867 47, Tx. 626 535

ROHDE & SCHWARZ, Werk Köln Graf-Zeppelin-Straße 18 Postfach 980260 D-5000 Köln 90

Spain REMA Leo Haag S.A

Thailand B. Grimm & Co. R.O.P. G.P.O.B. 66

Turkey

For Eastern European countries

For other areas not listed contact: ROHDE & SCHWARZ GmbH & Co. KG

GmbH & Co. KG. · D-8000 München 80 · Mühldorfstr. 15 · Tel. (089) 41 29-1 Int. + 49 89 41 29-1 · Telex 5 23 703

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Signal Generator SMK

mit besonderen Modulationseigenschaften: Ein rauscharmer AM/FM-Synthesizer-Signalgenerator

Frequenzbereich 10 Hz ... 140 MHz, Einstellzeit < 40 ma
Frequenzauflösung 1 H
Ausgangspegel 0,025 μV...2 V an 50 Ω
Pegeleinstellung unterbrechungsfrei über 20 dB, Auflösung 0,1 dB
Störstrahlung unter den Grenzwerten nach MIL-Standard 461 B, Part 7
SSB-Testeingang zur Erzeugung eines Einseitenbandspektrum:

SSB-Phasenrauschen –135 dBc/Hz bei 20 kHz Trägeroffset
Störhub <1 Hz entsprechend CCITT, <3 Hz (30 Hz ... 20 kHz
Nichtharmonische -80 dBc

Modulationsmöglichkeiten AM, FM, AM + FM, 2-Ton-AM, 2-Ton-FM, AC/DC
Interner Modulationsgenerator 150 Hz, 400 Hz, 1 kHz, 3 kHz, 15 kHz
Pegelregelung für externe Modulationssignale
AM bis 100% bei fmod DC ... 20 kHz
AM-Klirrfaktor 0,2 % (f_mod = 1 kHz, m = 80 %)
FM bis 500 kHz Hub bei fmod DC ... 100 kHz
FM-Klirrfaktor 0,02 % (f_mod = 1 kHz, Hub = 100 kHz) Stereoübersprechdämpfung 60 dB (500 Hz ... 10 kHz, Hub = 40 kHz)

Wobbelablauf 3 Hz, 30 Hz, 100 Hz, zählergenaue Anzeige der Mittentrequenz
Hub einstellbar bis 500 KHz

Variationstasten für alle Parameter
40 Geräteeinstellungen nichtflüchtig speicherba

SMK IST VOLLSTANDIG IEC-BUS-FERNSTEUERBAR (IEEE 488

Listener, talker, service request

Low-noise AM/FM Synthesizer Signal Generator

Frequency range 10 Hz to 140 MHz, setting time <40 ms
Frequency resolution 1 Hz
Output level 0.025 μV to 2 V (50 Ω)
Level variation 20 dB without interrupting RF output, resolution 0.1 dB
RF leakage below limit values of MIL STD 461 B, Part 7
SSB test input for generating SSB spectrum

SSB phase noise -135 dBc/Hz at 20 kHz from carrie
Spurious FM <1 Hz in compliance with CCITT, <3 Hz (30 Hz to 20 kHz)
Nonharmonic spurious signals

Modulation modes AM, FM, AM + FM, 2-tone AM, 2-tone FM, AC/DC
Level control tor external modulation signals
AM up to 100% at fmod DC to 20 kHz
AM distortion factor 0.2% (f_mod = 1 kHz, m = 80%)
FM up to 500 kHz deviation at fmod DC to 100 kHz
FM distortion factor 0.02 % (f_mod = 1 kHz, dev. = 100 kHz)

Sweep frequency 3 Hz, 30 Hz, 100 Hz, counter display of centre frequency
Deviation adjustable up to 500 kHz

Variation buttons for all parameters
Nonvolatile memory for 40 front-panel setups
Comprehensive selftest with error indication

Listener, talker, service request

ROHDE&SCHWARZ

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2.	Preparation for Use and Operating Instructions
2.1	Explanation of Figures 2-4 and 2-5 2.1
2.2	Preparation for Use 2.6
2.2.1	Power Fuse 2.6
2.2.2	AC Supply Voltage 2.6
2.2.3	Rack Mounting 2.7
2.3	Operation
2.3.1	Switched-on Status 2.9
2.3.2	Reference Frequency 2.9
2.3.3	Frequency Setting 2.10
2.3.3.1	Varying the Frequency 2.10
2.3.4	Level Setting 2.11
2.3.4.1	Varying the Level 2.12
2.3.4.2	Level Variation without Interruption 2.12
2.3.5	Modulation 2.13
2.3.5.1	Modulation Sources for AM 2.13
2.3.5.2	Modulation Sources for FM 2.14
2.3.5.3	Entering the AM 2.15
2.3.5.4	Entering the FM 2.17
2.3.5.5	Setting the Internal Modulation Generator
2.3.5.6	Internal Sweep (FM // INT) 2.18
2.3.5.7	FM DC 2.19
2.3.5.8	Preemphasis 2.20
2.3.5.9	Modulation Display 2.21
2.3.5.10	Varying the Modulation 2.21
2.3.5.11	ALC, External Level Control 2.21
2.3.6	Storage Capabilities 2.21
2.3.7	Self-test 2.22
2.3.8	Special Functions 2.22
2.3.8.1	Clearing of All Special Functions (RCL.00)
2.3.8.2	SSB Test (RCL.11, RCL.10) 2.24
2.3.8.3	Noninterrupting Level Setting in the Extended 20-dB Range (RCL.21, RCL.20)
2.3.8.4	Increased Signal-to-Noise Ratio in FM Operation (RCL.31, RCL.30) 2.25
2.3.8.5	Increased Signal-to-Noise Ratio in AM Operation (RCL.41, RCL.40)

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	Plant Counting Time (PCI 51 PCI 50)	2.26
2.3.8.6	Reduced Counting Time (RCL.57, RCL.50)	2.20
2.3.8.7	Disabling the Counter (RCL.61, RCL.60)	2.26
2.3.8.8	Increased Intermodulation Suppression (RCL.71, RCL.70)	2.26
2.3.8.9	Display Test (RCL.90)	2.26
2.3.8.10	Signature Analysis (RCL.91)	2.27
2.3.8.11	Test of the Electronic Attenuator (RCL.93, RCL.92)	2.27
2.3.8.12	Disabling the Self-test (RCL.94)	2.27
2.4	IEC-bus Control	2.28
2.4.1	Description of Interface	2.28
2.4.2	Address Setting	2.31
2.4.3	Remote/Local	2.31
2.4.4	Remote-control Commands	2.32
2.4.4.1	SMK as Listener	2.32
2.4.4.2	SMK as Talker	2.36
2.4.5	Device Clear	2.36
2.4.6	Service Request	2.36
2.4.7	Programming Examples	2.37
2.5	Options and Accessories	2.39
2.5.1	Option Overvoltage Protection SMK-B3	2.39
2.5.2	Option Reference Oscillator SMS-B1	2.39
2.5.3	Accessories	2.39

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Table of Contents

3.	Maintenance Instructions	3.1
3.1	Required Measuring Equipment and Accessories	3.1
3.2	Checking the Rated Specifications	3.4
3.2.1	Displays and Controls	3.4
3.2.2	Frequency Setting	3.4
3.2.3	Reference Frequency	3.5
3.2.4	Settling Time	3.5
3.2.5	Output Level	3.6
3.2.6	Attenuator Set	3.6
3.2.7	Noninterrupting Variation	3.7
3.2.8	Output Reflection Coefficient	3.7
3.2.9	RF2 Output	3.7
3.2.10	Harmonics	3.8
3.2.11	Nonharmonic Signals	3.8
3.2.12	SSB Phase Noise	3.9
3.2.13	Broadband Noise	3.11
3.2.14	Residual FM	3.11
3.2.15	Modulation Generator Sinewave	3.12
3.2.16	Modulation Generator Sweep Signal	3.12
3.2.17	Functional Test of Modulation Inputs	3.12
3.2.18	Automatic Level Control of External Modulation	3.13
3.2.19	AM Modulation Depth	3.13
3.2.20	AM Distortion Factor	3.13
3.2.21	AM Frequency Response	3.13
3.2.22	ALC (AM DC)	3.14
3.2.23	Residual AM	3.14
3.2.24	Incidental ØM in AM Operation	3.14
3.2.25	Intermodulation Suppression in 2-tone AM Operation	3.15
3.2.26	FM Frequency Deviation	3.15
3.2.27	FM Distortion	3.16
3.2.28	FM Frequency Response	3.16
3.2.29	FM DC	3.16

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Table of Contents

3.2.30	Stereo Separation	3.17
3.2.31	Unweighted S/N Ratio Stereo	3.17
3.2.32	Unweighted S/N Ratio Mono	3.17
3.2.33	Preemphasis	3.18
3.2.34	Incidental AM in FM Operation	3.18
3.2.35	SSB Test Input Intermodulation Suppression	3.19
3.2.36	Interface Functions	3.19
3.2.37	Response Threshold of Overvoltage Protection,
	Option SMK-B3	3.19
3.3	Performance Test Record	3.20

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AM/FM SYNTHESIZER SIGNAL GENERATOR SMK

10 Hz to 140 MHz

(IEC 625 Bus

* High frequency stability
* Frequency resolution 1Hz
* Low SSB phase noise -134 dBc/Hz at 10 kHz from carrier
* Low spurious FM < 1Hz (CCITT)
* Output level 0.025 µV to 2 V into 50Ω
* Level setting in µV, mV, dBµV, dBm, dBf
* Large variety of modulation modes 2-tone AM, 2-tone FM, AM + FM, AD/DC * Internal modulation generators for
sinewave and sweep * Low modulation distortion
0.02% in FM, 0.2% in AM
* Stereo crosstalk 60 dB down
* Input for generating SSB test signals
* Nonvolatile storage of 40 instrument settings
* All functions programmable via IEC 625-1 or IEEE-488
* Comprehensive self-testing with error indications

TECHNISCHE INFORMATION/TECHNICAL INFORMATION

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The Synthesizer Signal Generator SMK is a fully programmable signal generator covering continuously the frequency range of 10 Hz to 140 MHz.

Its frequency range, frequency resolution, signal quality and excellent modulation characteristics make the SMK the ideal instrument for all measurements on shortwave receivers including SSB receivers as well as AM and hi-fi FM broadcast receivers.

Since all functions can be programmed via the IEC 625-1 or IEEE-488 bus, the SMK is also well suited for use in semi- or fully automatic measuring setups.

OPERATION

Clear arrangement of the front panel by the split up of the keyboard and display into three separate fields for frequency, modulation, and level.
Keyboard inputs in the normal order numerical value and unit.
Direct digital readout with high resolution and automatic shift of decimal point.
Easy variation of all settings. Frequency, modulation and level can be varied by means of the readout, keys, each pair of keys controlling a decade of the readout. The settings are changed stepwise either in single steps or rapidly by keeping the key depressed.
Upward or downward change of frequency in steps of any desired size can be executed with the 2f kHz key.
Signal level may be displayed in one of five units.
Stored settings: Whenever the modulation, the level, or the instrument itself is switched off, the settings remain stored in memory and on switch-on are automatically effective. Independently of this feature, 40 instrument settings can also be stored in the nonvolatile memory.
Incorrect entries are not accepted by the instrument. The operator is informed of the erroneous setting by the blinking of the display involved.

FREQUENCY

The frequency may be set to values from 10 Hz to 140 MHz, the value being indicated to 9 places in Hz, kHz, or MHz. The fine re-

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solution of 1 Hz permits measurements on SSB receivers and narrow-band instruments. In place of the internal frequency standard, an external control frequency (1 or 5 or 10 MHz) may be applied.

The error in the frequency readout is equal to the error of the frequency standard, except in the operating modes Sweep int. and FMDC. In these two modes the frequency measured by a counter is displayed.

LEVEL

The output level, which may be set from -138.9 to 19 dBm in 0.1-dB steps, is displayed to four places in µV, mV, dBµV, dBm, or dBf. The level may be changed in steps of 10 dB, 1 dB, or 0.1 dB. The level may be varied in 0.1-dB steps over a range of 10 dB without interruption of the RF level - a characteristic that is indispensable for squelch measurements. The level range over which noninterrupting level setting is possible may be increased to 20 dB by calling a special function.

A 6-dB star coupling of two SMK's leads to intermodulation products <-80 dBc, up to 0 dBm generator level.

SPECTRAL PURITY

The output signal is of high spectral purity. The nonharmonic spurious signals, including the contribution of the power network and microphonic noise, lie typically more than 75 dB below the carrier level. The SSB phase noise at 20-kHz separation from the carrier is -135 dBc for a 1-Hz bandwidth. Because of this low phase noise, the spurious FM remains extremely weak, being < 3Hz for a measurement bandwidth of 30 Hz to 20 kHz. Because of this high spectral purity, the SMK can be used for all critical adjacent-channel measurements and measurements on SSB receivers.

MODULATION

The signal generator provides low-distortion, broadband AM and FM settable in small steps. The many modulation possibilities include 2-tone AM, 2-tone FM, simultaneous AM and FM, internal and external sweep, with DC and AC coupling for all modulation modes. The SMK is provided with two input connectors each for AM and FM external modulating signals. For 2-tone modulation or simultaneous AM and FM modulation either two external sources or the internal and one external modulation source may be used.

The AM and FM modulating signals can be independently adjusted in both 2-tone and AM + FM operation.

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Internal modulation generators:

Internal modulation generators: The SMK modulation sources are provided by a generator producing pure sinusoidal signals of frequency 150 Hz, 400 Hz, 1 kHz, 3 kHz, 15 kHz, and a generator producing linear triangular sweep signals at repetition rates of 3, 30, and 100 Hz.

External modulation:

Each of the AM and FM input circuits (AM1 and FM1) are equipped with automatic level control. This control has the purpose of limiting the modulation depth and frequency deviation to within specified tolerances for a large range of external modulation voltage (0.5 < Vrms < 2V).

The rear-panel AM input, (AM2) is DC-coupled. The rear-panel FM input (FM2) can be switched to AC or DC coupling.

Pilot-subcarrier input FM3:

A separate pilot-tone input permits variation of the deviation of the stereo signal while holding the pilot subcarrier constant.

AM DC:

AM DC permits the varying of the signal amplitude under voltage control. It is used when the signal generator is operated in an ALC loop with an external measuring point.

FM DC.

DC coupling of the FM modulation signal is required for FSK (frequency-shift keying) modulation. A further application together with the vector voltmeter ZPV is the determination of crystal resonances of a test assembly, which is self-tuning with the aid of a phase-control loop. DC coupling permits sweep operation with an external triangular or sawtooth voltage. With FM DC an internal frequency counter furnishes the correct frequency indication. This frequency value can be read out via the IEC bus.

Sweep:

A sweep can be controlled either by the internal triangular sweep generator or by an external source via the FM-extern input FM2 with DC coupling. The deviation (±500 kHz max.) in both cases is set on the keyboard.

In addition to the sweeping of tuned circuits, FM demodulators. IF filters or IF amplifiers, the SMK with its extremely low spurious FM and high frequency stability is particularly suited for sweeping crystal and ceramic filters with extremely steep skirt selectivity.

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FM and AM Characteristics:

The broad FM range to 100 kHz with small phase rotation permits high-quality stereo modulation and also the transmission of the 57-kHz auxiliary carrier for traffic radio identification. With an inherent distortion factor of less than 0.1%, the SMK is particularly suited for all distortion measurements on VHF receivers. Amplitude modulation is without restriction possible down to the lowest carrier frequency, and thus measurements in the low-frequency and AM IF bands are possible without restriction. The very low AM distortions (typically 0.2%) permit measurements on high-quality AM receivers.

SSB TEST INPUT

A -20-dBm signal of 40 MHz ± 4f applied to the test input is converted in amplitude and frequency to the entered output level and the entered frequency f_c ± Δf. Intermodulation measurements on SSB receivers, which normally require two high-quality signal generators, can be carried out with a single SMK by inserting two such signals into the test input.

SELF-TEST

The most important functions of the frequency synthesis are continuously monitored during operation. Errors are indicated on the display and an error message is output via the IEC bus.

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Data Sheet Signal Generator SMK

Frequency

Range	10 Hz to 140 MHz
Resolution	1 Hz
Error for CW, AM, FMAC for FMDC, Sweep int.	Reference frequency error Reference frequency error ±2 Hz
Setting time (after recei- ving last character via IEC bus)	< 40 ms (to within 100 Hz of final frequency)
Reference frequency	From internal reference oscillator or from external source
Internal reference oscillator	Standard Option SMS-B1
Aging	<2 x 10 ^-8 /day <2 x 10 ^-9 /day
Temperature coefficient	<1 x 10 ^-6 /°C <2 x 10 ^- 9/°C
Warm-up time	1 hour 15 min.
Output/input for internal/ext 10 MHz (common socket)	cernal reference frequency 1, 5,
Output voltage with internal reference	TTL level
Input voltage with external reference	>100 mV sinewave or TTL
Spectral purity
Harmonics	<-30 dBc, typical <-36 dBc
Nonharmonics	<-65 dBc, typical <-75 dBc
Nonharmonics (power and micro phonic noise) for CW and AM	o- <-65 dBc, typical <-75 dBc
Noise (referred to 1-Hz bands	width)
SSB phase noise 20 kHz from carrier 5 kHz from carrier	<-130 dBc, typical <-135 dBc <-124 dBc, typical <-130 dBc

- 6 -

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Broadband noise > 2 MHz from carrier<-140 dBc1 (for CW and FM)</th>Residual FM, rms<1 Hz (CCITT) <3 Hz (30 Hz to 20 kHz)</td>

Typical SSB phase noise (for CW)

f = 120 MHz

in dBc/Hz

¹ When level VAR indication is 0 dB.

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	- 0 -
Level switch-off (RF OFF)	Switch-over to minimum output level The output impedance remains unchan- ged.
Level at RF output 2	50 mV ¹ (for CW and FM)
Modulation
Modulation modes	Internal: AM, FM and ~ sweep External: AM AC/DC, FM AC/DC
2-tone AM	AM INT + AM EXT (Connector AM2) or 2 x AM EXT (Connectors AM1 and AM2)
2-tone FM	FM INT + FM EXT (Connector FM2) or 2 x FM EXT (Connectors FM1 and FM2)
AM + FM	Any combination of AM, FM, Ext., Int.
Internal modulation	Sinewave 150 Hz, 400 Hz, 1 kHz, 3 kHz, 15 kHz Sweep 3, 30, 100 Hz
Frequency error	< 0.1%
Outputs	AM1, FM1 on the front panel EMF: 1 V sinewave, ± 5 V sweep, R ₀ = 600 Ω
External modulation
Inputs	AM1, FM1 on front panel AM2, FM2, FM3 on rear panel
	Inputs AM1 and FM1 with ALC
Input impedance	600.2: AM1, FM1 10k/2: AM2, FM2, FM3
Input level V _rms ²	0.5 < V < 2 V for AM1, FM1 1 V for AM2, FM2, FM3
Amplitude modulation
Modulation depth, m	0.5% to 100%
Resolution	0.5%

² Required input level for the specified accuracies.

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- 9 -<5% of entered value1 Error for m = 80% Modulation frequency range 20 Hz (DC) to 20 kHz AM EXT <1 dB, typical 0.3 dB Modulation frequency response (20 Hz to 10 kHz) <0.5% up to 2 MHz, typical 0.2% Distortion <1% above 2 MHz, typical 0.4% (m = 80%, fMOD = 1kHz) < 0.01% (CCITT) Residual AM, rms <0.02% (30 Hz to 20 kHz) Incidental phase modulation (for m = 30%, fMOD = 1 kHz) <0.1 radian Frequency Modulation 0.05 to 500 kHz Frequency deviation 0.05 kHz to 10 kHz deviation Resolution 0.5 kHz 10 to 100 kHz deviation 2 kHz 100 to 500 kHz deviation < 3% of entered value or 10 Hz Deviation error Modulation frequency range 20 Hz to 100 kHz for FM EXT AC for FM EXT DC DC to 3 kHz Modulation frequency response < 0.2 dB (20 Hz to 100 kHz)³ Distortion (deviation 100 kHz) for fMOD = 1 kHz <0.05%, typical 0.02%³ for fMOD = 100 Hz to 20 kHz < 0.2% Distortion for stereo <0.1% (for 1-kHz audio) (deviation 40 kHz) Stereo crosstalk down > 45 dB (40 Hz to 15 kHz)³ (deviation 40 kHz) down > 56 dB (500 Hz to 10 kHz)

Unweighted S/N ratio stereo >70 dB (CCIR (dev. 40 kHz, preemphasis 50µs) 30 Hz to 20 kHz)³ Unweighted S/N ratio mono >76 dB (CCIR

(dev. 40 kHz, preemphasis 50µs) 30 Hz to 20 kHz) ³

3 for FM AC

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	- 10 -
Switchable preemphasis	50 µs (link-selectable between 75 and 750 µs)
Incidental AM (dev. 40 kHz, fMOD = 1 kHz)	<0.2% (for carrier frequency >10 MHz) ³
Sweep Frequencies
Internal frequencies	3, 30, 100 Hz
Deviation	0.05 to 500 kHz
Resolution	As in frequency modulation
Sweep out put signal	±5 V triangular, on connector FM1
Input for SSB test signals
Frequency	40 MHz ± ∆f (∆f ≤ 500 kHz)
Level	-20 dBm for the output level shown in the display

Maximum level -10 dBm

Intermodulation products of 3rd order for two input signals

d3 in the A3J sideband > 60 dB

d3, f ≥ 30 kHz >60 dB

Programming and data output

System IEC-625-1/IEEE-488

24-contact Amphenol connector

Interface functions:

T6 Basic Talker, Serial Poll, Unaddress if MLA L4 Basic Listener, Unaddress if MTA SR1 Service Request Function Complete Capability RL1 Remote/Local Function Complete Capability DC1 Device Clear Function Complete Capability

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Options

Reference Oscillator Option SMS-B1 See under "Frequency" above.

Overvoltage Protection Option SMK-B3

Protects the RF output against external RF (1 to 500 MHz) and DC voltages.

Maximum permitted RF power 30 W

Miximum permitted DC voltage 35 V

Response indications LED in the RF OFF key and "O.L." in the level display.

General Data

Rated temperature range +5 to +45°C

Shelf temperature range -40 to +70°C

AC supply

RF leakage

In compliance with VDE 0871 (radio interference and interference on the connecting cables) and VDE 0875 (limit values of radio interference grade K).

Shock and vibration resistance

Shock-tested in accordance with DIN 40046, Part 7 (30 g, 11 ms) and vibration-tested in accordance with DIN 40046, Part 8 (11 to 55 Hz, 2g). These standards correspond to IEC Publications 68-2-27 and 68-2-6.

Dimensions

Weight

345 x 198 x 462 mm

100/120/220/240 V ±10%,

VDE-0411 Safety Class I.

47 to 420 Hz, 110 VA, 95 Watt,

20.5 kg

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Ordering Information
Order designation
Signal Generator SMK	348.0010.02
Accessories supplied	Power cord, manual
Options
Reference Oscillator SMS-B1	302.8918.02
Overvoltage Protection SMK-B3	358.8013.02

lGAS-0134-e lü-pr 3.83

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2. Preparation for Use and Operating Instructions

The values given in this section are not guaranteed. The guaranteed values are specified in the Data Sheet.

The following description of the SMK controls and displays refer to Figs. 2-4 and 2-5 (in Appendix).

Item No.	Marking	Function
1		9-digit field for displaying the radio frequency. When the keys RCL and LOCAL are pressed, the IEC-bus address is displayed in this field.
2	Ŷ ↓	Keys for varying the radio frequency in single steps or (by keeping the key depressed) stepping it rapidly. The size of the step is equal to the decimal value of the digit position under which the key is located.
3		Two keys for stepping the internal modulation or sweep frequencies, the upper key for stepping to the next higher and the lower key to the next lower frequency. These keys function only for AM-INT, FM-INT, and sweep- INT operation.
4	f _INT ~ 15 4 1, 3 15 kHz 3 30 100 Hz	Display of the output frequencies of the internal modulation generator (upper row) and sweep generator (lower row). A pointer in the dis- play field indicates the modulation or sweep frequency being output.
5		3-digit field for display of the mo- dulation index in AM operation, the peak frequency deviation in FM ope- ration, and the sweep width in sweep operation. For simultaneous AM and FM, either the percent modulation or the frequency deviation can be selec- ted for display. When either of the variation keys 3 is operated to se- lect the internal modulation frequen- cy, this frequency is shown in the field. If the special function SSB Test is switched in, the letters SSB are displayed in the field.

2.1 Explanation of Figures 2-4 and 2-5

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Item No.	Marking	Function
6	① J	Four keys for varying the percent mo- dulation in AM, frequency deviation in FM, and sweep width in sweep, ope- ration in single steps or quasi-con- tinuously by keeping the key de- pressed. The size of the step is equal to the decimal value of the digit po- sition under which the key is located.
7		4-digit field for display of the RF output level and the selected unit. For varying the RF level without interrupt- ing it, a bar display is shown above the markings 10 dB 0 indicat- ing the distance to the upper and lower limit of the 10-dB range over which level setting is possible without switching the RF level off. (This range may be increased to 20 dB with use of the special function RCL.21).
8	10 1 0.1 10 1 0.1 ↓ dB ↓ dB ↓ J	Keys for varying the RF level in dB in single steps or quasi-continuously by keeping the key depressed. The size of the step, 10, 1, or 0.1 dB, is marked on the key. The 0.1-dB variation pro- ceeds without interruption of the RF level over a 10-dB range (which may be extended to 20 dB with use of the special function RCL.21).
9	REMOTE	LED for indicating the remote-control status.
10	LOCAL	Key for switching from remote-control to manual operation. This key is also used in the keying sequence RCL LOCAL to display the IEC-bus address in the frequency field 1 .
11	7 8 9 4 5 6 1 2 3 0 • - CE STO RCL	Keyboard for entering numeric values, plus key CE for deleting an incomplete or incorrect input, STO for storing the entered value, RCL for calling up stored values and special functions.

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Item No.	Marking	Function
12	POWER (OFF)	Power on-off switch.
13	RF OFF	Key for switching the RF level on or off. When the RF is switched off, the LED in the RF OFF key lights; the out- put impedance remains unchanged. The level readout is not changed when this key is operated. A response of the overvoltage protec- tion circuit (option) is indicated by the lighting of the LED in the RF OFF key together with the readout "O.L." in the level display field. After the overvoltage has been removed, the pro- tection circuit is reset by pressing the RF OFF key.
14	RF1 50 Ω	RF output, BNC socket, 50 Ω.
15	dBm □ □mV dBf □ □µV dBµV□	Five keys for entering the RF level. After keying in the value of the level on the keypad 11 , the unit is entered by pressing one of these keys. The unit may be changed by pressing the desired unit key without first entering a numeric value.
16	PREEMPH.	Key for switching preemphasis in or out in FM operation. The key lights when the preemphasis is switched in.
17	AM 1	In AM INT operation, the internal modu- lation signal (1 V) is output on this BNC socket. In AM EXT operation, the external modulation signal is applied to this socket. The built-in constant- level control circuit (MOD ALC) permits an input voltage between 0.5 and 2 volts.
18	FM2 DC	Key for selecting either DC or AC coup- ling of the modulation signal inserted via rear-panel socket FM2. In FM DC operation, this key and the FM EXT key are both lit.

(

Page 32

Item No.	Marking	Function
19	FM1	In FM INT and FM ~ (sweep) opera- tion, the internal modulation signal (1 V _rms for sinewave and 5 V _pp for sweep operation) is output on this BNC socket. In FM EXT operation, the exter- nal modulation signal is applied to this socket. The built-in constant- level control circuit (MOD ALC) permits an input voltage between 0.5 and 2 V. 600 Ω.
20	FM ~	Key for switching the internal sweep generator in or out. When the internal sweep is switched in, this key and the FM INT key are both lit.
21	INT. EXT. OFF OOO 4M % FM kHz	Six keys for setting up AM and FM ope- ration. If a numerical value has been keyed in on the keypad, the pressing of one of the four keys fitted with LED completes the entry of this value and defines the modulation mode - AM or FM, internal or external. If no value has been keyed in on the keypad, the pressing of one of these four keys selects the modulation mode and fet- ches from memory the value stored at the last switch-off. The modulation mode switched in is indicated by the lit-up LED. AM and FM can be separate- ly switched off by means of the two OFF keys.
22	Δf kHz +	Two keys for varying the RF frequency in freely selectable step sizes. The value of the step size is initially keyed in on the keypad and then ente- red, and the frequency step executed by pressing one of these keys. The step size remains stored for subse- quent execution of the steps. If the key is kept depressed, the frequency is varied quasi-continuously.
23	HHz kHz F	Two keys for entering the frequency. The frequency value is first keyed in and then entered by pressing one of these keys.
24	IEC 625 IEEE 488	IEC bus connector for remote control.

Page 33

Marking		Function
SSB 40 MHz	÷	Input socket for SSB test signals. 50 Q.
RF2	-	Second RF output, Level 25-50 mV into 50 Ω (when the VAR readout is 0 dB).
RF1	•	Opening for the possible relocation of the RF1 output socket from the front to the rear panel.
		Ventilator.
FM1		Two openings for the possible reloca- tion of the FM1 and AM1 modulation signal sockets from the front to the
		rear panel.
FM2 AC/DC	-	Second input for FM modulation signal, switchable to AC or DC coupling. 10 kΩ.
FM3	÷	Third input for FM modulation signal as a separate input for a pilot tone. 10 kΩ.
AM2 ALC	-	Second AM input with DC coupling of the modulation signal. 10 kQ.
REF.FREQ. 1/5/10 MHz	→	Output socket for the internal refe- rence frequency. The output frequency of 1, 5 or 10 MHz may be selected. TTL output level. By suitably changing internal bridge connections, the SMK can be operated with an external 1, 5 or 10-MHz refe- rence signal applied to this socket. Level > 100 mV sinewave or TTL.
47 - 420 Hz		AC power supply connector.
220 220 240 001		Fuse holder and AC voltage selector.
	Marking SSB 40 MHz RF2 RF1 FM1 AM1 FM2 AC/DC FM3 AM2 ALC REF.FREQ. 1/5/10 MHz 47 - 420 Hz	Marking SSB 40 MHz ← RF2 ← RF1 ← FM1 ← AM1 ← FM2 ← AC/DC ← FM3 ← AM2 ← ALC ← AM2 ← ALC ← AM2 ← ALC ← AM2 ← ALC ← AL ←

Page 34

Item No.	Marking	Function
36	100-V/120-V T2,5C 220-V/240-V T1,6C	Fuse values for the different AC voltages.
37	Option Ref. 052 SMS-B1 302.8918.02 Option Üb.spg. Schutz SMK-B3 358.8013.02	The instrument is equipped with the ref. oscillator (SMS-B1) and/or the overvoltage prot. (SMK-B3) option, as indicated by the corss(es).

2.2 Preparation for Use

2.2.1 Power Fuse

The power fuse is mounted in the power-fuse holder 35 (Figs. 2-5 and 2-1). The size of the fuse for the different AC supply voltages 36 is printed on the rear panel above the fuse holder (Fig. 2-1). The holder can be disengaged by applying the tip of a screw driver to the recess on the right side and prying the holder loose.

Fig. 2-1 Power plug, AC supply voltage selector, fuse holder.

2.2.2 AC Supply Voltage

The SMK can be operated with a 100-V, 120-V, 220-V, and 240-V AC supply voltage. Before placing the instrument in use, the AC supply voltage selector should be checked to see that it is set to the voltage being used. For adapting the instrument to the given AC supply voltage, the appropriate fuse for this voltage is inserted in the fuse holder and the latter reinserted so that the marking of the voltage being used is at the top of the fuse-holder cover directly under the mark on the holder housing.

Page 35

The 100-V and 120-V AC supply voltages require a T2,5D fuse, the 220-V and 240-V AC supply voltages require a T1,6D fuse.

2.2.3 Rack Mounting

The SMK can be mounted in any 19" rack with use of the 19" Rackmount Set SMK-Z6 (Order No. 358.8213.02).

Special care must be taken that intake and outflow of cooling air is not hindered in any way.

The air intake 28 and outlet (front edge of upper cover) must be kept unobstructed.

To create a free space for unimpeded air flow, the dummy plate furnished with the instrument should be mounted over the front panel of the SMK.

Page 36

2.3 Operation

The instrument is manually set by means of keys. The keys and displays are divided into four groups, each occupying a field on the front panel. In the left field are the control keys and the display for the radio frequency, in the next field those for the modulation parameters. In the third field, above the RF1 socket, are the keys and displays for the RF level. The field on the right contains the keypad for inputting data (11), the STO key for storing keyed-in values, the RCL key for fetching stored items from memory, the CE key for deleting an incorrect keyed-in value, and the remote lamp and local key.

A setting is made in the sequence numerical value (if required) on keypad 11 and then the unit or function (in all cases).

The unit and function keys are the lower sets of keys in the RF, modulation, and level fields. The double rows of keys above them are variation keys for stepwise changing the RF frequency, modulation depth or frequency, and RF level. When one of these keys is kept depressed, the value of the parameter is varied quasi-continuously (rapid stepping upward or downward).

For all states that may be switched in or out, LEDs in the keys indicate if the operating state corresponding to the key marking is switched in. With each of the eight keys with an LED there is an associated adjustable parameter whose value is stored in memory when the operating mode is switched out. When this operating mode is switched in again without a new value for the parameter having been entered, the old value is fetched from memory and used again. Stored values are preserved even in case of power switch-off.

It is impossible to set the instrument to an unpermitted operating state. In case of entries which excluse each other, for example FM // INT and FM2 DC EXT, the last one chosen is established, and the other switched out. If it is attempted to enter a parameter value outside its permitted range, it is not accepted and has no effect on the instrument setting. The displayed value of the parameter, or of an associated parameter, blinks to signal such an incorrect entry. An example of the case where the display of an associated parameter blinks is the following: With an RF level > 13 dBm, only a limited modulation depth is possible. If it is attempted to enter a modulation depth incompatible with the established RF level, the RF-level display blinks. On the other hand, the attempted entry of an RF level incompatible with the established modulation depth causes the modulation display to blink. The

Page 37

blinking of a display ends after a short period automatically. It is also terminated by any subsequent keying.

The variation of the frequency, modulation, or level ends automatically at the end of the permitted range. Excess number of places after the decimal point are ignored. The appearance in the frequency display field of a blinking readout of --PLL-- signalizes that an error has occurred in the frequency synthesis and that the output frequency is incorrect. The appearance in the level display field of the readout O.L. (in place of the level value) indicates that the (optional) overvoltage protection has responded to an overvoltage condition.

All settings that are manually possible can also be made by remote control via the IEC bus. In the following instrument-setting instructions, the corresponding IEC-bus commands are also specified.

2.3.1 Switched-on Status

When the SMK is switched on, the set IEC-bus address is briefly displayed. After this initialization phase, the instrument status which existed when the instrument was last switched off is restored (with the exception of the special functions, see section 2.3.8).

If a storage error is detected, the following basic state is established:

→ RF = 1 MHz → Level = -138.9 dBm → "RF ON" → All special functions deleted → Modulation switched out, with the presetting m = 50% → Deviation = 1 kHz → AF INT = 1 kHz → Sweep frequency = 30 Hz → IEC-bus address 8

2.3.2 Reference Frequency

The output frequency of the Signal Generator SMK is derived from a 60-MHz crystal oscillator. One of the derived frequencies of 1, 5 or 10 MHz is brought out on rear-panel socket 33. At the factory, this reference-frequency output is set to 10 MHz; the 1-MHz or 5-MHz signal can be brought out to this socket instead by repositioning appropriate links on Reference Board Y10 (348.4096).

Page 38

The option SMS-B1 - a temperature-controlled reference oscillator - is described in section 2.5.2.

The SMK can also be driven by an external reference-frequency signal of 1, 5 or 10 MHz. The conversion to the external reference and its frequency is made by repositioning plug-in links on Reference Board Y10.

The plug-in positions of the links on Reference Board Y10 for internal and external control and for selecting the desired frequency (1, 5 or 10 MHz) are shown on a schematic diagram etched on the board.

2.3.3 Frequency Setting

The frequency range of the SMK is 10 Hz to 140 MHz. The desired value is keyed on keypad 11 (Fig. 2-4). The entry of the value is then completed by pressing one of the unit keys MHz or kHz 23. The entered value is displayed in digital field 1 in the units MHz, kHz or Hz, with or without a decimal point.

Examples

2.3.3.1 Varying the Frequency

The frequency can be changed by means of the keys of the double row 2 in single steps equal to the decimal value of the digit position of the key being operated. The smallest step is 1 Hz, the largest 10 MHz. The variation is upward (

Variation in steps of freely selectable size.

The value of the desired step size is keyed in, in kHz, on keypad 11. The step is then executed by pressing one of the keys A f kHz + or - (22).

Page 39

This step size is stored and is used in subsequent operations of the \Delta f kHz keys until it is overwritten by a new step size. A rapid sequence of steps is executed when a \Delta f kHz key is kept depressed.

Any step size from 1 kHz to the largest possible step over the entire frequency range is permitted.

Keys 22

Example:

Keypad 11

2.3.4 Level Setting

The RF level may be set to a value between 19 dBm and -138.9 dBm, or 2 V and 0.025 µV into 50 Ω for CW and FM.

In AM operation, the maximum enterable level lies between 13 and 19 dBm, depending on the modulation depth. If in AM operation, too high a level is input, the modulation depth display blinks to indicate the value that is incompatible with the entered level.

The desired level value is keyed in on the keypad 11 (Fig. 2-4) and the entry completed by pressing one of the unit keys dBm, dBf, dBµV, mV, µV 16. The level is displayed in the digit field 7 in the chosen unit with or without a decimal point.

If the level is to be readout in another unit, it is only necessary to press the key for this unit (without any further numerical input).

The level is switched out by pressing the RF OFF key 13. In this operating mode, the LED in the RF OFF key lights, the level readout remains unchanged at the old value. If the RF OFF key is then pressed again, the level output is restored to its previous indicated value.

Page 40

2.3.4.1 Varying the Level

With the variation keys 8, the level may be varied in dB steps of size 10, 1 or 0.1 dB, independently of the unit in which the level is displayed.

2.3.4.2 Level Variation without Interruption

RF level variation without interruption of the level is provided for by the two 0.1-dB keys 8. When these keys are used, an electronic attenuating circuit with a dynamic range of 10 dB is used in place of the more common mechanical attenuators which interrupt the circuit each time they switch. The 10-dB range of noninterrupting level adjustment extends from the level set at the time of the first operation of the -0.1-dB key to the 10-dB lower level. By exceeding the limits of this range, a new setting of the mechanical attenuator occurs permitting a 10-dB variation without interrupting the RF level. To indicate the position of the current RF level in this 10-dB dynamic range, a 10-segment bar indication is provided in the level display, the bar appearing above the marking -10 dB ----- 0. When in the upward variation of the level the last, righthand segment of the beam disappears, there is still a 0.5-dB interval left before the mechanical attenuator switches. In the downward variation, when the last, left segment appears, there is similarly a 0.5-dB interval left at the lower end before mechanical switching occurs.

2.12

Page 41

The range of noninterrupting level variation may be extended to 20 dB by use of the special function RCL.21. (See section 2.3.8).

The correct RF output level is also displayed in the level display field 7 during such noninterrupting level variation.

In remote control of the instrument, the mechanically switching attenuator is disabled with the ATT1 command. In the -10-dB range (-20-dB range with special function RCL.21) extending from the level set at the time of the ATT1 command to the 10-dB (20-dB) lower level, noninterrupting level adjustment is provided in response to the normal program level commands. If either limit of the established 10-dB (20-dB) range is exceeded, the mechanical attenuator is reset to the new level and a new range of noninterrupting level adjustments extending to -10 dB (-20 dB) below the new level is set up.

Example:

Assume 3 dBm level setting:

Keypad

IEC bus

"ATT1," (mechanical attenuator disabled)

"LDBM-2,"

Noninterrupting adjustment of -2 dBm with the 0.1-dB variation key.

2.3.5 Modulation

Amplitude, frequency and sweep modulation are provided. The modulation depth and frequency deviation can be individually adjusted even for simultaneous amplitude and frequency modulation. Five input connectors are provided for inserting external modulation signals and an internal generator furnishes a sinewave for AM or FM and a triangular wave for sweep modulation.

2.3.5.1 Modulation Sources for AM

For amplitude modulation, three sources are available - the internal modulation generator and 2 sockets, AM1 17 and AM2 32, for inserting external signals.

Input AM1 is AC coupled and provided with automatic level control which can regulate an input signal between 0.5 and 2 V_rms so accurately that the modulation depth error remains within the specified tolerances. The settling time is several seconds.

2.13

Page 42

Input AM2 is DC coupled. The required input level for modulation is 1 V_rms. Because of the DC coupling, the AM2 input is suitable for external level control (ALC). The range of modulation lies between -1.41 and +1.41 V.

A modulation signal input on socket AM1 cannot be combined with an internally generated modulation signal. When the internal generator is switched in with the AM INT key (which then is lit), its output is switched onto the AM1 socket for external use. When the AM1 socket is switched for input by setting the AM EXT key, the internal generator is disconnected.

The input to the AM2 socket (32) can be used alone (LED AM EXT on, and no input on socket AM1) or together with one of the other modulation sources. 2-tone AM operation is possible with a modulation signal from the internal source (LED AM INT on) and the second signal on socket AM2, or with two external signals (LED AM EXT on) applied to inputs AM1 and AM2 respectively.

The signals of the three modulation sources are led over the same modulation divider, whose division factor is set for the desired modulation depth. In 2-tone AM operation, the entered and displayed modulation depth is equal to the modulation depth value generated by a single modulating signal. With an input of 1 V_rms on socket AM2, the sum modulation-depth value is twice that of the displayed value.

2.3.5.2 Modulation Sources for FM

Four modulation-signal sources are available for FM - the internal modulation generator and the three sockets FM1 20, FM2 30, and FM3 31 for inserting external signals.

Input socket FM1 is AC coupled and provided with automatic level control which regulates any signal between 0.5 and 2 V_rms to keep the deviation-frequency error within the specified limits. The settling time of the control circuit is several seconds. The level control produces a slight increase in the harmonic distortion of input signals of frequency < 100 Hz. If this cannot be tolerated, the FM2 input should be used.

Input FM2 may be switched to either AC or DC coupling, with the FM2 DC key. The required input level for modulation is 1 V_rms. With DC coupling, the FM2 socket may be used for inserting sweep signals or control voltages for VCO applications. The modulation range lies between -1.41 and +1.41 V.

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A signal applied to socket FM3 causes a frequency deviation which is independent of the frequency deviation value entered via the keyboard. With an input voltage of 1 V_rms, the deviation is 6.72 kHz. This socket can be used for inserting the pilot tone for constant pilot-tone modulation, whereas the multiplex signal without pilot tone is inserted on input FM1 or FM2.

A modulation signal input on socket FM1 cannot be combined with an internally generated modulation signal. If the internal modulation generator is switched in (LED FM INT on), its output is also switched onto socket FM1 for external use. When socket FM1 is switched for input (LED FM EXT on), the internal modulation generator is disconnected.

External modulation signal applied to sockets FM2 and/or FM3 are utilized regardless of whether the internal modulation source (LED FM INT on) or the external input to socket FM1 (LED FM EXT on) is selected. The input to socket FM2 can also be used alone (LED FM EXT on, no input to socket FM1).

2-tone FM operation is possible either with the internal source and the input on socket FM2 (LED FM INT on) or with two external signals applied to FM1 and FM2 (LED FM EXT on).

The internal and external modulation signals applied to sockets FM1 and FM2 are led over the same modulation divider, whose division factor is set to the frequency deviation. For 2-tone FM, the entered and displayed deviation are equal to the deviation generated by one signal. With an input voltage of 1 V_rms on the FM2 socket, the sum deviation is equal to twice the displayed value.

2.3.5.3 Entering the AM

The modulation depth may be set to a value between 0.5 and 100% in steps of 0.5%. At RF levels greater than 13 dBm, the permitted maximum value of the modulation depth decreases with increasing level. The instrument itself checks that this maximum is not exceeded and treats an attempt to enter a value greater than this maximum as an out-of-range input.

Amplitude modulation is switched in when either one of the two keys AM INT or AM EXT is pressed, either with or without a prior numerical entry. If no numerical entry was made, the stored value of the parameter is fetched from memory and used. With the AM INT key, the internally generated modulation signal is selected, with the AM EXT key, the external signal applied to socket AM1 is selected.

2.15

Page 44

In AM operation, depending on the modulation source selected, either the LED AM INT or LED AM EXT is on. These two keys are coupled, so that when one of them is switched on, the other is switched off.

The modulation depth, after its value, in %, has been keyed in on keypad 11, is entered by pressing either the AM INT or AM EXT key, depending on which modulation source is to be used.

The AM is switched off by pressing the AM OFF key.

Examples:

33% AM, internal modulation source

80% AM, external modulation source on socket AM1

EXT

Switch-in of AM with internal modulation source without prior numerical entry

"AMI,"

"AMØ,"

IEC bus

"AMI 33."

"AME 80."

Switch-off of AM

348.0010.02

Page 45

2.3.5.4 Entering the FM

The frequency deviation may be set to any value in the range 0.05 to 500 kHz. FM is switched in by pressing one of the two keys FM INT or FM EXT, with or without prior input of a numerical value. If no value was input, the stored value of the parameter is fetched from memory and used. With the FM INT key, the internally generated modulation signal is selected for use, and with the FM EXT key, an external modulation signal. The external modulation source is connected to socket FM1.

In FM operation, the LED in either the FM INT or the FM EXT key is on, depending on the modulation source switched in. The two keys are coupled so that when one is switched in, the other one is switched out.

The frequency deviation, after its value has been keyed in, in kHz, on keypad 11, is entered by pressing either the FM INT or FM EXT key, depending on the modulation source being used.

INT

6H7

kHz

The FM is switched off by pressing the FM OFF key.

Examples:

150-kHz deviation, internal modulation source

IEC bus

"FMI 150."

"FME 25.5."

25.5-kHz deviation, external modulation source connected to socket FM1

Switch-in of FM with internal modulation source without prior numerical entra

"FMI."

Switch-off of FM


FM kHz

OFF

"FMØ,"

Page 46

2.3.5.5 Setting the Internal Modulation Generator

The internal modulation generator can furnish either sinewave signals or triangular sweep signals. It is switched in as modulation source for AM with the AM INT key, for FM with the FM INT key, and for sweep with the FM // INT key. The internally generated sinewave frequencies of 150 Hz, 400 Hz, 1 kHz, 3 kHz, 15 kHz and the sweep frequencies of 3 Hz, 30 Hz, 100 Hz are listed below the modulation display field 5. In internal-modulation operation, the frequency of the generator output is indicated by a light pointer.

The internal modulation signal is output for external use on socket AM1 in AM INT operation and on socket FM1 in FM INT and FM // INT operation.

The frequency is set with the pair of keys 3, without any numerical input. When the upper/lower key is pressed, the next higher/lower frequency is switched in.

So long as one of these keys is kept depressed, the frequency is displayed in digital display field 5. In AM INT and FM INT operation, the modulation signal is a 1-V_rms sinewave, in internal sweep operation (LED of the FM // INT key is lit) a triangular wave, 5 V_pp. The frequency of the modulation signal is stored in nonvolatile memory when the operating mode is switched off.

2.3.5.6 Internal Sweep (FM INT)

The internal sweep is switched in and out with the FM // INT key. When the sweep is switched in both LEDs FM // INT and FM INT are on. After the frequency sweep-width value, between 0.05 and 500 kHz, has been keyed in in kHz on keypad 11, it is entered by pressing the FM INT key. The switching out of the internal sweep with the FM // INT key results in a switch-over to internal sinewave modulation (LED FM INT remains lit). The internal sweep is also switched out by pressing the FM OFF key, in which case FM INT is also switched out.

Sweep INT and AM INT are not possible at the same time. An attempt to input it is rejected by the instrument and the LED display of the switched-in modulation blinks briefly. Similarly, sweep INT and DC coupling of the modulation input socket FM2 are not possible at the same time. For this reason, the two keys FM INT and FM2 DC are coupled so that when either key is pressed, the other key is switched out.

Page 47

The frequency readout in internal sweep operation shows the measured centre frequency of the sweep range. This frequency can drift slightly from the entered RF frequency since in this operating mode the modulated oscillator is not phase synchronized.

Examples:

Switch-in of internal sweep, in which the stored values of the sweep width and sweep frequency of the last internal sweep operation are used.

Setting the sweep width 400 kHz:

		LNT
4 0	0	• FM kHz	"FMI 400,"

Setting the sweep frequency 3 Hz

2.3.5.7 FM DC

The DC coupling of the FM2 modulation input is switched in with the in/out FM2 DC key. When the DC coupling is switched in, both the LEDs of FM2 DC and FM EXT keys are lit. The range of modulation is -1.41 to +1.41 V. The modulation sensitivity is established with the setting of the frequency deviation. The deviation value, between 0.05 and 500 kHz, is entered by keying in the value in kHz on keypad 11 and pressing the FM EXT key. For VCO applications with maximum frequency deviation - a tuning range of ±500 kHz about the entered frequency is possible.

When the DC coupling is switched out with the FM2 DC key, the frequency modulation mode FM EXT remains in operation. DC coupling of input FM2 and internal sweep are not possible at the same time. For this reason, the two keys FM INT and FM2 DC are coupled so that, when one of these keys is pressed, the other one is switched off. With DC coupling, the frequency display shows the measured frequency. Even with O-V input, a slight shift away from the entered RF frequency is possible since in FM DC operation the controlled oscillator is not phase-synchronized.

E-1

IEC bus

"SW 1."

"SWF 1,"

Page 48

Examples:

Switch-in of FM DC operation, in which the stored value of frequency deviation (from the last setting) is used:

EXT • FM2 DC

"DC 1,"

IEC bus

Entering a frequency deviation of 125 kHz:

		****
1 2	5		FM kHz	"FME 125,"

FYT

2.3.5.8 Preemphasis

In FM operation, preemphasis can be switched in and out with the PREEMPH. key 16. The LED of the key is lit when preemphasis is switched in. The preemphasis is set at the factory to 50 µs. By repositioning a shorting plug on the Modulation Control Board Y14 (348.1374), the preemphasis can be changed to 75 or 750 µs. The 50-µs, 75-µs or 750-µs preemphasis is selected by inserting the shorting plug in positions X1, X2 or X3, as shown in Fig. 2-2.

Fig. 2-2 Shorting plug positions X1, X2, X3 on board Y14.

Page 49

2.3.5.9 Modulation Display

The 3-digit field 5 displays the modulation depth in AM operation and the frequency deviation in FM operation. The value displayed in case of simultaneous AM and FM modulation depends on the key last operated. The percent modulation is displayed when the AM INT or AM EXT key is pressed, the frequency deviation when the FM INT, FM EXT, FM INT, or FM2 DC key is pressed. To switch between the frequency deviation and modulation depth displays, the lighted key of the operating mode whose parameter is to be displayed is pressed without any new value being input. When one of the modulations is switched off by pressing the AM OFF or FM OFF key, the parameter value of the still active modulation is automatically displayed.

The internally generated modulation frequencies are listed below the modulation display field. In internal modulation operation, the frequency cut in is indicated there by a light pointer.

2.3.5.10 Varying the Modulation

The displayed parameter value may be changed by means of the four variation keys 6. In combined AM and FM operation, this is either the modulation depth or frequency deviation.

2.3.5.11 ALC, External Level Control

In AM operation, external level control is possible via the DC-coupled modulation input AM2 32. The range of modulation is -1.41 V to +1.41 V. The modulation sensitivity is determined by the modulation depth.

With maximum sensitivity (m = 100% entered), the upper modulation limit (+1.41 V) corresponds to a level rise of 6 dB, the lower limit (-1.41 V) to a level attenuation of about 50 dB of the entered (and displayed) level. It should be noted that the maximum level reached by modulation cannot lie above 19 dBm.

2.3.6 Storage Capabilities

All settings of the instrument can be stored. The stored data are not lost when the instrument is switched off. The supply battery of the memory has a life of several years. A total of 40 instruments settings can be stored.

A complete instrument setting is stored by pressing the STO key and a number from 01 through 40 on keypad 11.

2.21

Page 50

Examples:

IEC bus

"STO 01,"

The stored values can be fetched with the RCL key of keypad 11 and the instrument reset accordingly. The syntax is the same as for the STO instruction, the STO key being replaced by the RCL key.

A special function is performed by the call RCL O. With it the instrument setting which was replaced by the last memory call RCL n is reset.

Example:

IEC bus

All data fetched from memory are checked for syntactical correctness to prevent any inadmissible settings to arise because of memory faults. If such an error is detected, the instrument is set to its basic setting:

RF = 1 MHz, level = -138.9 dBm.

2.3.7 Self-test

The SMK has a self-test program for testing the most important functions of the frequency synthesis. If an error leading to an incorrect frequency occurs, the display -- PLL -- appears in the frequency display field. An error message can be sent via the IEC bus in this case (see 2.5.6 Service Request).

2.3.8 Special Functions

The normal instrument functions are augmented by special functions, which provide for additional applications of the instrument. A special function is switched in by pressing the keys RCL, decimal point, and a 2-digit number on keypad 11. These functions are deleted when the instrument is turned off (or a power failure occurs). When a complete instrument setting is stored with the STO command, any special functions in use are also stored, with the exception of special functions RCL.90-94, in nonvolatile memory.

Page 51

2.3.8.10 Signature Analysis (RCL.91)

For servicing purposes, signature analysis is switched in with RCL.91. A description of signal analysis is contained in section 4. When signature analysis is switched in, the instrument does not respond to any key manipulation or IEC-bus input. The operating mode signature analysis is indicated by three transverse segments in each of the three display fields.

The signature analysis can be switched off only by switching off the power.

2.3.8.11 Test of the Electronic Attenuator (RCL.93, RCL.92)

For servicing purposes, the electronic attenuator can be set to 10 dB attenuation with RCL.93.

The same setting would be obtained if the level were lowered by 10 dB with use of the -0.1-dB variation key (noninterrupting level variation).

The correct value of the output level is indicated in the level display. The bar display of the value of the electronic attenuation stands at -10 dB. With RCL.92, the electronic attenuation is returned to 0 dB and the original output level thereby restored.

2.3.8.12 Disabling the Self-test (RCL.94)

The self-test of the instrument is switched off with RCL.94 for servicing purposes. Self-test is reactivated with RCL.00.

Page 52

2.4 IEC-bus Control

Provision for remote control in accordance with the specifications of publications IEC 625-1 and IEEE 488 is a standard feature of the SMK. The bus connector 24 (Fig. 2-5) is located on the rear panel of the instrument.

2.4.1 Description of Interface

Fig. 2-3 Connector pin assignment

The connector specified in the American standard IEEE 488-1975 differs from that of the international IEC standard. The SMK is equipped with the more widely used 24-pole IEEE connector. Connection to devices with the 25-pole IEC connector is easily possible with use of an adapter. The control functions and data transfer are identical.

The standardized interface system contains three groups of bus lines:

Data bus, with 8 lines DI/O 1 to DI/O 8. Data transfer is bit parallel and byte serial, the characters being transmitted in ISO 7-bit code (or ASCII code). DI/O 1 represents the lowest-order and DI/O 8 the highest-order bit.

2.28

Page 53

RCL.00 Clears all Special Functions
- RCL.11 Switches in operation mode SSB test.
- RCL.10 Switches out operation mode SSB test (normal function).
- RCL.21 Extends the range of noninterrupting level variation to 20 dB.
- RCL.20 Switches the range of noninterrupting level variation back to 10 dB (normal function).
- RCL.31 Switches off internally modulation input FM1 for measurements requiring maximum signal-to-noise ratio.
- RCL.30 Switches modulation input FM1 in again (normal function).
- RCL.41 Switches off internally modulation input AM1.
- RCL.40 Switches modulation input AM1 in again (normal function).
- RCL.51 Switches the gate time of the frequency counter active in FM DC and FM // INT operation to 0.1 sec.
- RCL.50 Switches the gate time of the frequency counter to 1 sec (normal function).
- RCL.61 Switches off the internal frequency counter.
- RCL.60 Switches in the internal frequency counter (normal function).
- RCL.71 Switches the internal level control to a sample-and-hold operation.
- RCL.70 Switches in normal operation of the level control.
- RCL.90 Switches in the display test.
- RCL.91 Switches in signature analysis.
- RCL.92 Switches electronic attenuator to 0 dB.
- RCL.93 Switches electronic attenuator to 10 dB.
- RCL.94 Switches off self-test for purposes of servicing.

Page 54

2.3.8.1 Clearing of All Special Functions (RCL.00)

This special function clears all other special functions and restores the instrument to the normal state.

2.3.8.2 SSB Test (RCL.11, RCL.10)

The special function SSB Test is switched in with the call RCL.11. The output of the internal 40-MHz oscillator is switched off and replaced by the SSB-test input on socket 25. The level and frequency of the SMK output signal are then directly related to the level and frequency of the test signal fed in. The test frequency 40 MHz ± Δf has the effect of shifting the output frequency ± Δf from the entered (and displayed) RF. With an input level of -20 dBm on socket 25, the level of the output signal coincides with the entered (and displayed) level. A level deviation of the test signal produces an equal deviation of the output level. The maximum allowed input level is -10 dBm, the maximum frequency difference Δf is 500 kHz.

The two signals required for intermodulation measurements can be generated in the whole range of frequency and level to which the SMK can be set by inserting two signals with fixed frequencies and constant levels.

In SSB-test operation, the readout SSB appears in the modulation display field. AM and FM operation are not possible - they are switched off when the special function is called. The maximum level that can be keyed in is -1 dBm.

The special function SSB Test is switched out by keying in RCL.10.

Examples:

Page 55

2.3.8.3 Noninterrupting Level Setting in the Extended 20-dB Range (RCL.21, RCL.20)

Noninterrupting level variation is described in section 2.3.4.2. By keying in RCL.21, a 20-dB range is provided by the special function over which noninterrupting setting of the level is possible. A 10-segment bar indication of the level within the 20-dB dynamic range functions as follows: when the level is changed in the upward direction and the last segment on the right of the bar display disappears, there is 1 dB of noninterrupting variation in the upward direction left. In the downward variation, when the last segment on the left appears, there is 1 dB of noninterrupting variation in the downward direction left.

The entering of RCL.20 restores normal functioning in regard to noninterrupting level stepping without affecting any other special functions.

Example (see also 2.3.4.2):

Keypad

Assume set level to be 3 dBm Noninterrupting level range 20 dB:

6		ſ
	RCL		•	2	1
l		L			L

"ATT 1," (disabling of mechanical attenuator) "LDBM-12,"

TEC hus

"SF 21."

Noninterrupting setting of -12 dBm with the 0.1-dB key.

2.3.8.4 Increased Signal-to-Noise Ratio in FM Operation (RCL.31, RCL.30)

For determining the unweighted or weighted S/N ratio, the signal generator is frequency modulated with a deviation of, for example, 40 MHz for measurement of the reference voltage. For measuring the extraneous or noise voltage, the signal generator is normally switched to CW. If, otherwise, the FM operation mode is not switched off (SINAD), the special function RCL.31 should be used. This function raises the S/N of the signal generator.

With RCL.31, the instrument disconnects the modulation input FM1. The external modulation signal must be input on socket FM2.

Normal functioning, with socket FM1 internally connected, is restored with RCL.30.

2.25

Page 56

2.3.8.5 Increased Signal-to-noise Ratio in AM Operation (RCL.41, RCL.40)

Special function RCL.41 performs the same function for AM as RCL.31 for FM (see 2.3.8.4). The modulation input AM1 is internally disconnected. External modulation must be input via socket AM2. Normal functioning, with socket AM1 internally connected, is restored with RCL.40.

2.3.8.6 Reduced Counting Time (RCL.51, RCL.50)

In normal functioning, the counting time of the frequency counter active in FM DC and FM /// INT operation is 1 sec. and the counter resolution is 1 Hz. With special function RCL.51, the counting time is switched to 0.1 sec. and the resolution to 10 Hz.

Normal functioning is restored with RCL.50.

2.3.8.7 Disabling the Counter (RCL.61, RCL.60)

With RCL.61, the counter can be disabled for test purposes. In the frequency display, the entered value, and not the measured value, is displayed in all cases, including FM DC and FM /// INT operation.

Normal functioning with counter in operation is restored with RCL.60.

2.3.8.8 Increased Intermodulation Suppression (RCL.71, RCL.70)

With RCL.71, the internal level control is converted to a sample-and-hold operation. In this operating mode, the SMK can be operated in the usual way without any restrictions.

For multiple transmitter measurements, an increase in the intermodulation suppression results. If for the combination of the signal generators a simple 6-dB star is used, the modulation suppression is more than 80 dB for transmission levels up to 0 dBm. With Power Combiner DVS (3 dB transmission loss), the intermodulation suppression remains greater than 80 dB even at a transmission level of 19 dBm.

2.3.8.9 Display Test (RCL.90)

A check of the functioning of all display elements can be carried out with special function RCL.90. All drivable segments appear in the display and all LEDs light. The display test is switched off as soon as any key is operated.

Page 57

2. Control bus, with 5 lines.

This bus serves for the transfer of control functions.

ATN (Attention) Line is active LOW during an address transmission to the connected devices. Serves for switching a device to the remote-REN (Remote Enable) control state. Permits a connected device by activating this SRQ (Service Request) line to request a service call from the controller. IFC (Interface Clear) Line is activated to bring the connected devices to a defined initial state. EOI (End or Identify) Can be used to signal the end of a data transfer and serves also for polling the devices after a service request.
3. Handshake bus, with 3 lines.

This bus serves for controlling the time sequence of the data transfer.

NRFD	Active LOW on this line signifies to the con-
(Not Ready for Data)	troller that one of the devices is not ready
	to accept data.
DAV	Line is activated by the controller shortly
(Data Valid)	after a data byte has been placed on the data
	bus.
NDAC	Line is held active LOW by a connected device
(Not Data Accepted)	until it has accepted the data on the data bus.

The commands for data output vary somewhat in the computers of the different manufacturers. In Table 2-1 are shown some examples of outputting parameter settings as it is done in the most widely used desktop computers. In these examples the decimal address of the SMK is taken as 8.

2.29

Page 58

Page 59

Table 2-1 Setting Commands

	R&S	hp	hp	Tektronix *
	PUC	9835/9845	9835/9845	4051/4052
Frequency 123.5 MHz	IECOUT8,"RFMH123.5,"	wrt7Ø8,"RFMH123.5,"	OUTPUT7Ø8;"RFMH123.5,"	PRINT@8:"RFMH123.5,"
Frequency as variable	F = 123.5	F = 123.5	LET F = 123.5	LET F = 123.5
	IECOUT8,"RFMH"+STR$(F)+","	wrt7Ø8,"RFMH",F,","	OUTPUT7Ø8;"RFMH";F;","	PRINT@8:"RFMH";F;","
Level 117 mV	IECOUT8,"LMV117,"	wrt7Ø8,"LMV117,"	OUTPUT 7Ø8;"LMV117,"	PRINT@8:"LMV117,"
Talker	IECOUT8,"RFHZ,"	wrt7Ø8,"RFHZ,"	OUTPUT7Ø8;"RFHZ,"	PRINT@8:"RFHZ,"
Query SMK frequency	IECIN8,A$	red7Ø8,A$	ENTER7Ø8;A$	INPUT@8:A$

Go to Local	IECLAD8 IECGTL IECUNL	lc17Ø8 lc17 **	LOCAL7Ø8 LOCAL7 **	WBYTE@4Ø,1:
Local Lockout	IECLLO	1107 (for all instruments)	LOCAL LOCKOUT 7 (for all instruments)	WBYTE@4Ø,17: or WBYTE@17:
Remote	IECREN	rem7Ø8 or rem7	REMOTE7Ø8 or REMOTE7	WBYTE@4Ø
Selected Device Clear	IECLAD8 IECSDC IECUNL	clr7Ø8	RESET7Ø8	WBYTE@4Ø,4:

* When operated with desktop computer Tektronix 4051, the bus line REN (connector pin 17) must be connected with chassis. This can be done with a shorting plug.

** LOCAL7 switches the REMOTE line out.

Ó 3 ZENTIMETER

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2.4.2 Address Setting

The device address can be entered on the front panel or via the IEC bus. The address is stored in nonvolatile memory until it is overwritten by a new address entry. The range of available addresses is 0 to 30. The address of the SMK is set at the factory to 8.

A new address is entered on the front panel by keying in the number on keypad 11 and then pressing the keys RCL and LOCAL. The new address is then displayed for a few seconds in the frequency display field 1.

The pressing of keys RCL and LOCAL without having keyed in a number results in the established address being briefly displayed in the frequency display field.

Example

Readout of established address

Entering the address 22

IEC bus

"IECA."

"IECA 22,"

2.4.3 Remote/Local

In response to inputs from the controller, the SMK goes automatically into the REMOTE (remote-controlled) state and remains in it even after the output is completed. This state is indicated by the lighting of the REMOTE LED 9 (Fig. 2-4). All front panel controls are disabled.

LOCAL

If a manual setting is then to be made, program execution by the controller must first of all be stopped. After that the SMK can be switched to manual operation by pressing the LOCAL key 10. The desired setting can then be made.

The controller can also place the instrument in the LOCAL state by sending the control command GTL (Go To Local).

The switch-over to the LOCAL state by means of key 10 can be prevented by outputting the command LLO once (Local Lock Out) over the IEC bus, preferably at the beginning of program execution.

Table 2-2 includes examples for the outputting of the foregoing commands. The SMK address is taken to be 8. This decimal address corresponds to the full decimal equivalent 40.

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Page 61

2.4.4.1 SMK as Listener

The setting commands consist of a header (obligatory), data (optional), and a delimiter (obligatory).

The header is an easily remembered letter-digit combination with reference to the function and unit of the parameter being set.

Permissible delimiters are: /,/NL/CR+NL/ETB/ETX/EOI/

Places in the data field exceeding the resolution of the device are ignored.

Page 62

Table 2-2

Function	Header	Data	Delimiter
Set RF in MHz kHz Hz	RFMH RFKH RFHZ	up to 9 places decimal point (DP) exponential form	, CR+NL ETB ETX EOI
Set level or convert to dBm dBf dBµV mV µV	LDBM LDBF LDBU LMV LUV	up to 4 places, DP " " "	11
Set level, noninterrupting Set level, normal	ATT1 ATTØ *		11 11
Switch out RF Switch in RF	RFØ * RF1		11 11
Set internal AF to 150 Hz 400 Hz 1 kHz 3 kHz 15 kHz	AF1 AF2 AF3 AF4 AF5		11
Set internal sweep frequency to 3 Hz 30 Hz 100 Hz	SWF1 SWF2 SWF3		11
Switch out AM Switch in external AM or reset in % Switch in internal AM	AMØ * AME	up to 3 places, DP	11
or reset in % Switch out FM Switch in external FM or reset in kHz Switch in internal FM or reset in kHz	AMI FMØ * FME FMI	" up to 3 places, DP "	,,

Page 63


Function	Header	Data	Delimiter
Switch out FM DC coupling Switch in FM DC coupling	DCØ * DC1		n
Switch out preemphasis Switch in preemphasis	PRU PR1
Switch out internal sweep	FMØ *		11
Switch in internal sweep	SW1
Switch from sweep to internal FM	swø
Set sweep width in kHz	FMI	up to 3 places, DP
Store entire instrument setting	STO	n (n:1-40)
Call entire instrument setting	RCL	n (n:1-40)	11
Set IEC address	IECA	X (X:Ø-3Ø)
Special functions:
Clear special functions	SFØØ *
SSB test in	SF11
SSB test out	SF1Ø
Noninterrupting 20-dB level variation in	SF21		11
Noninterrupting 10-dB level variation out	SF2Ø
Switch out FM1 mod. input Switch in FM1 mod. input	SF31 SF3Ø SF41
Switch in AM1 mod. input	SF4Ø
Counter gate time 0.1 sec "1 sec	SF51 SF5Ø
Counter disabled "enabled	SF61 SF6Ø		11
Level control in sample-and-hold	SF71
Level control in normal operation	SF7Ø
Display test in	SF9Ø
Signature analysis in	SF91
			!

Page 64

Function	Header	Delimiter
Electronic level reduction to -10 dB	SF93
Electronic level reduction to 0 dB	SF92	11
Switch off self-test	SF94
Block service request	SRQØ	~
Permit service request: for error message	SRQ1
Permit service request: for reporting the steady- state condition after change of frequency	SRQ2	11
Permit service request: for error message and reporting the steady- state condition after change of frequency	SRQ3
Talker function Output RF in Hz	RFHZ
Define delimiter for talker function:	-
EOI only NL with EOI ETX " " ETB " " CR and NL " "	ZØ * Z1 Z2 Z3 Z4	"
NL without EOI ETX " " ETB " " CR and NL " "	Z5 Z6 Z7 Z8

* These settings are made in response to the Device Clear command. This command also sets the frequency to 1 MHz and the level to -138.9 dBm.

2.4.4.2 SMK as Talker

On receipt of the command "RFHZ", the SMK stores the current carrier frequency in an auxiliary memory. If it is then addressed as talker, the SMK outputs the stored value. The carrier frequency is always output in Hz. The delimiter is defined in the program (see Command Table). The query of the frequency only makes sense for FM DC and FM //INT operation, since in all other operating modes the readout frequency is the same as the entered frequency.

Page 65

2.4.5 Device Clear

On the Device Clear command, the instrument is reset to RF = 1 MHz. 1evel = -138.9 dBm. Modulation and special functions are cleared.

The modulation parameters are preset as follows:

m = 50%, frequency deviation = 1 kHz, AF INT = 1 kHz, sweep frequency = 30 Hz. In Table 2-2 of the IEC-bus setting commands, the settings resulting from the Device Clear command are marked with +.

Service Request 2.4.6

If the controller permits the service request, with the command "SRQ1", the SMK reports various different input errors, the activation of the overvoltage protection, and errors detected in the self-test by activating the SRQ line. As response to the resultant serial poll, the SMK sends the status byte, which has the following meaning:

Table 2-3

Status byte decimal equiv.	Significance
65	Error in the frequency synthesis (incorrect output frequency).
66	Response of overvoltage protection.
67	Frequency input out of range.
68	Level input out of range.
69	Modulation input out of range.
70	RF level too high for the selected AM index.
71	Syntax error.
72	Input with given device status not compatible.

2.4.6.1 Detection of Steady-state Condition

If the controller permits service request with the command "SRQ2", the SMK reports the steady-state condition after a change of frequency by activating the SRQ line. The decimal equivalent of the status byte that is output by the resultant serial poll is 80.

The controller can interrogate the status byte without using service request. As soon as the decimal equivalent of the status byte changes from 0 to 80, the SMK has reached the steady state.

Relevant examples are given in section 2.4.7.

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2.4.7 Programming Examples Frequency setting a) 117, 123456 MHz "RFMH 117.123456." b) 17 Hz "RFKH Ø.Ø17." Level setting a) -17.6 dBm "LDBM -17.6." b) 150 mV "LMV 150." "LDBU." c) Readout of entered level in dBuV d) 10 dBm "LDBM 10." The next level settings are to be noninterrupting: Disable mechanical attenuator "ATT1." Between 10 dBm 8 dBm "LDBM8." and 0 dBm, every level can be set without 0.5 dBm "LDBMØ.5." interruption as often as desired 6 dBm "LDBM6." RF level switched out "RFØ." a) Switch out RF level b) Switch RF level in again "RF1." Modulation setting "AME 55," a) AM, m = 55%, external modulation source on socket AM1 b) Switch in FM with no new value "FMI," input, internal modulation "AF3." c) Internal modulation frequency = 1 kHz d) Switch in internal sweep generator "SW1." as modulation source e) Internal sweep frequency = 30 Hz "SWF2." f) Set sweep width of 500 kHz "FM1500." g) Switch out internal sweep "FMØ."

Page 67

Commands can also be written one after the other on one line. 37.15 MHz RF 43 uV Level 7 Internal amplitude modulation 80 45 kHz External frequency modulation Input FM2 DC-coupled kHz Internal modulation frequency "RFMH37.15, LUV43, AMI80, FME45, DC1, AF4," Programming examples with the R&S Process Controller PUC Example 1: The SMK reports the steady-state condition after a change of frequency with the status byte. 100 S7 = Ø IECOUT8,"SRQ2" Device address 8: 110 permit service request. 120 TECOUT8, "RFMH12,3" SMK frequency setting. 130 Serial poll: waiting loop until IECSPL8,S% status byte 80 is read 140 TF S% = Ø THEN 130 Continuation of the program after 150 steady-state condition has been detected 16Ø by interrogation of the status byte. Example 2: The SMK reports the steady-state condition after a change of frequency with service request. 100 IECSRQ GOTO 1ØØØ 110 IECOUT8,"SRQ2" Device address 8: permit service request. S% = Ø 120 IECOUT8,"RFMH12.3" SMK frequency setting. 130 Continuation of the program immediately 14Ø after the last frequency setting command. 15Ø The SMK reports the steady-state condition with service request. 1000 REM SERIAL POLL 1010 IECSPL8,S% Service request sub-routine for interrogating the status byte. PRINT "STATUSBYTE:" SZ 1Ø2Ø 1ø3ø IECRETSRO

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2.5 Options and Accessories

2.5.1 Option Overvoltage Protection SMK-B3

The overvoltage-protection option protects the device against too high RF and DC voltage on output socket 14. The protection circuit is effective for frequencies from 1 to 500 MHz, up to 30 W power, and DC voltages up to 35 V. The response of the protective circuit is indicated by the display "O.L." in the level display field 7 and the lighting of the LED in the RF OFF key 13. In remote-control operation, a service-request message can be sent. The protective circuit is reset with the RF OFF key or with the remote-control command "RF1". The installation of the option is described in Part 5 of the subassemblies description "Overvoltage Protection".

2.5.2 Option Reference Oscillator SMS-B1

A temperature-controlled 10-MHz crystal oscillator is available as an option. The internal 60-MHz oscillator is phase synchronized with the unit. The installation of the option is described in part 5 of the service instructions for the Reference Board.

If the option is installed, only a 10-MHz signal is available on socket 33.

2.5.3 Accessories

The SMK contains an adapter board (348.4938), hung in on the rear side of the circuit-board cage, which permits a circuit board withdrawn from the cage for servicing to be connected into the instrument circuit. All supply voltages, address and data lines, as well as a part of the RF connections are led over the adapter board.

The RF adapter 348.4950.02 is available as a servicing accessory. This adapter can be inserted in place of any pluggable circuit board. The RF interfaces between the circuit board and motherboard 1 are then accessible via four subminax sockets.

The 19" Rackmount Set SMK-Z6 (358.8213.02) is available as accessory. In rackmounting, care must be taken to provide for unimpeded ventilation of the instrument. The air outlet slit on the front side of the instrument cover must be kept unobstructed.

To assure a free space for unimpeded air movement, the dummy plate shipped with the instrument should be mounted over the front panel of the SMK.

2.39

Page 69

Page 70

3. Maintenance Instructions

3.1 Required Measuring Equipment and Accessories

Item No.	Instrument	Required characteristics	R&S instr. Order No.	Use: see section
1	Frequency counter	Range 10 Hz to 140 MHz Resolution 1 Hz		3.2.2 3.2.3 3.2.15 3.2.16 3.2.29
2	Oscilloscope	DC to 5 MHz		3.2.4 3.2.12
3	Mixer	Range to 200 MHz Ring modulator, normal level		3.2.4 3.2.12
4	Lowpass 2 MHz	Attenuation at 10 MHz > 40 dB		3.2.4 3.2.12
5	Power meter	Range 10 Hz to 140 MHz Power to 20 mW Char. imp. 50 Ω Erro < 0.1 dB		3.2.5 3.2.7 3.2.9 3.2.22
6	Precision attenuator set	10 Hz to 140 MHZ Attenuation 0 to 120 dB Char. imp. 50 Ω	DPVP 214.8017.52	3.2.6
7	Test receiver	Range 20 to 140 MHz Self.noise < -10 dB/µV	ESV 342.4020.52	3.2.6
8	Precision forward cable	Char. imp. 50 Ω	SWOB-Z 100.3598.50	3.2.8
9	RF milli- voltmeter with insertion unit	Range 1 to 140 MHz Sensitivity 100 mV	URV 216.3612	3.2.8
10	RF analyzer	Range 0.1 to 500 MHz crystal stability, Dynamic range 90 dB		3.2.10 3.2.11 3.2.25 3.2.35

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Item No.	Instrument	Required characteristics	R&S instr. Order No.	Use: see section
11	AF analyzer	Range to 20 kHz		3.2.12
12	Switchable lowpass	30 to 150 MHz, 50 Ω		3.2.13
13	Spurious-FM meter	Range to 140 MHz Residual FM < 0.5 Hz (CCITT) < 1.5 Hz (30 Hz to 20 kHz)		3.2.14
14	Psophometer	CCITT weighting filter rms voltage detector	UPGR 248.1915	3.2.14 3.2.15 3.2.31
15	AF generator	Range 20 Hz to 100 kHz Distortion factor at 1 kHz < 0.02%		3.2.17 3.2.18 3.2.21 3.2.25 3.2.27 3.2.28 3.2.32
16	Modulation analyzer	RF range O.1 to 140 MHz AF range 20 Hz to 100 kHz AM O to 90% FM O to 500 kHz ØM O to 1 rad AM distortion < 0.2% FM distortion < 0.05%	FAM 334.2015.54	3.2.17 3.2.18 3.2.19 3.2.20 3.2.21 3.2.23 3.2.24 3.2.26 3.2.27 3.2.28 3.2.27 3.2.28 3.2.30 3.2.31 3.2.31 3.2.32 3.2.33 3.2.34
17	Distortion meter	Range 50 Hz to 20 kHz Measurement range to 0.03%		3.2.15 3.2.20 3.2.27
18	Stereo- coder Stereo- decoder	Channel separation > 60 dB	MSC 2 230.9314 MSDC 2 281.0514	3.2.30 3.2.31
19	DC power supply	0 to 10 V, I < 200 mA	NGT 20 117.7133	3.2.22 3.2.29

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Item No.	Instrument	Required characteristics	R&S instr. Order No.	Use: see section
20	RF generator	F generator 40 MHz		3.2.35
21	Power splitter/ combiner	40 MHz	DVS 342.1014.50	3.2.35
22	Control computer	Interface IEC 625-1	PUC 344.8900	3.2.36
	If Option SMK-B3 is installed, also:
23	Power signal generator	25 to 500 MHz Power output > 2 W	SMLU 200.1009	3.2.37

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3.2 Checking the Rated Specifications

3.2.1 Displays and Controls

The display test is switched in with special function RCL.90 and causes all display elements to light. The test is ended by pressing any key on the front panel. The functioning of the keys is tested by pressing them and checking the associated display for the correct response.

3.2.2 Frequency Setting

SMK settings: Unmodulated, level 0 dBm.

Test setup:

Synchronize reference frequency of SMK and counter.

Test:

Set the SMK to the following frequencies and check value set against counter reading:

2 MHz
9.999 999 MHz
10 MHz
44.9999999 MHz
125 MHz
140 MHz

The value reading on the counter must agree with the value set on the SMK to within ±1 in the last (1-Hz) digit of the field.

Page 74

3.2.3 Reference Frequency

- Let the SMK warm up for at least one hour.

- Connect a calibrated frequency counter to the rear-panel REF. FREQ. output. The relative frequency error must not exceed

in the standard SMK: 2 x 10^-8/ operating-day + 2 x 10^-5 *) SMK with SMS-B1 option: 2 x 10^-9/ operating-day + 4 x 10^-8 *)

*) over the normal temperature range.

3.2.4 Settling Time

To measure the settling time, the 10-MHz output frequency of the SMK is mixed with the 10-MHz internal reference frequency to obtain the difference frequency. This frequency and the settling time are measured with an oscilloscope.

Settings on SMK: unmodulated, level 0 dBm Oscillator: DC, 0.1 V/div, 5 ms/div, triggering AC, NORM, INT.

Measurements: a) Set output frequency to 10.0001 MHz. Set oscilloscope triggering to give a steady picture.

b) Switch output frequency from 9.9999999 MHz to 10.000000 MHz and back again.
c) On the oscilloscope read off the time at which the frequency difference is < 100 Hz.

This measured time is the settling time of the SMK without computer time. It must not exceed 30 ms.

Page 75

3.2.5 Output Level

SMK	settings:	unmodulated,	level	19 dBm,
		frequencies	10 Hz	to 140 MHz

Test setup: Connect power meter to RF output.

Test: a) The frequency response (difference between the highest and lowest level) must not exceed 1 dB.

b) The error in the output level at 20 MHz must not exceed 0.5 dB.

3.2.6 Attenuator Set

Settings on SMK:

SMK:unmodulated, 140 MHz, 9 dBm.Precision Attenuator set:120 dB attenuationTest receiver:40 MHz, -10, Linear, centre value, bandwidth 7.5 kHz.

Test setup:

Be sure all cable connections are RF leakage proof!

Test: Note the level indicated on the test receiver as reference value (appr. 6 dBµV).

Repeat the measurements for the settings given in Table 3-1.

Table 3-1

SMK level dBm	Attenuation of Precision attenuator set dB
19 17	120 118
15	116
	112
-1	100
	80
-61	40
-81
	ľ

The difference between any value obtained and the reference value must not exceed 1.2 dB.

348.0010.02

3.6

Page 76

3.2.7 Noninterrupting Variation

SMK settings: unmodulated, 20 MHz, 0 dBm

Test setup: Connect power meter to RF output.

Test: With the 0.1-dB key reduce the RF output level to -10 dBm and check the level jumps on the power meter. The permitted deviation at -10 dBm is ±0.5 dB.

If the value -10 dBm is inadvertently not attained in operating the finevariation key, the original O-dB setting must be restored and the level again reduced with the 0.1-dB key.

3.2.8 Output Reflection Coefficient

SMK settings: AM 0%, level 3 dBm, frequency 100 to 140 MHz.

Test setup:

Insertion unit

Test: Vary the frequency so that a voltage maximum is measured. Then adjust the frequency until the nearest voltage minimum is obtained (f = 7.5 MHz for a 10-meter long cable).

$VSWR = \frac{V_{max}}{V_{min}}$

3.2.9 RF2 Output

SMK settings: unmodulated, 20 MHz, 0 dBm

Test	setup:	Connect	power	meter	to	the	RF2	output	on	rear	panel.

Test: The output level must lie in the range -10 dBm to -16 dBm.

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3.2.10 Harmonics

SMK settings:	unmodulated, level 1 dBm,
	frequency 100 Hz to 140 MHz.
Test setup:	Connect RF analyzer to RF output of SMK.
Test:	The harmonics level must not exceed -30 dBc. If a higher reading is shown, check whether the analyzer is being overdriven.

3.2.11 Nonharmonic Signals

SMK settings:	unmodulated, level 0 dBm,
	frequency 100 Hz to 140 MHz.
Test setup:	Connect RF analyzer to RF output of SMK.
Test:	Check the nonharmonic suppression at (preferably)
	the following frequencies:

Table 3-2

SMK setting	Search frequency
39 MHz	59 MHz
80 MHz	40 MHz
90 MHz	50 MHz
100 MHz	±1 MHz ±20 MHz
119.995 MHz	±280 MHz
140 MHz	30 MHz 160 MHz

Permissible nonharmonics: < -65 dBc.

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3.2.12 SSB Phase Noise

The phase-quadrature measurement technique is used for measuring the SSB phase noise. If two signals of the same frequency and 90° phase difference are applied to a ring mixer, the output of the mixer contains a low-frequency component whose amplitude reflects the phase noise of the two RF signals. This signal may be amplified and measured with an AF spectrum analyzer to yield the noise level as a function of the frequency displacement from the carrier. The 10-MHz internal reference frequency is taken as the LO signal and the output signal of the SMK as the RF signal.

Settings of SMK: Unmodulated, frequency 10 MHz, level 0 dBm. oscilloscope: DC, 0.1 V/Div, triggering AUTO AF analyzer: Bandwidth 1 kHz, 2 kHz/Div.

Test setup:

Measurements: a) Set SMK to 10.005 (10.020) MHz.

b) Adjust the reference level of the spectrum analyzer so that the 5 (20)-kHz difference signal lies 6 dB below the reference level. This -6-dB offset is yielded by the double-sideband measurement. The specification applies however only for one sideband.

For a spectrum analyzer with a logarithmic amplifier and an average-responding rectifier, this offset must be corrected by +2.5 dB. An additional correction for noise bandwidth may be necessary. In most cases therefore the 5 (20)-kHz difference signal must be adjusted to about 3 dB below the reference level.

3.9

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c) Set the SMK to 10.000 001 MHz. With the 1-Hz-variation key, stop the beat on the oscilloscope at zero crossing. The two input signals to the mixer are then in phase-quadrature.
d) Read off the reference-signal-to-noise ratio at 5 (20) kHz on the analyzer. To this value 30 dB must be added for the conversion from the 1-kHz to the 1-Hz bandwidth.

The following values for the SSB phase noise must not be exceeded:

at 5 kHz displacement: < -125 dBc, at 20 kHz displacement: < -130 dBc.

To measure the SSB phase noise at carrier frequencies other than 10 MHz, the LO-signal input to the mixer must be provided by another signal generator. To assure an accurate measurement, the signal-to-noise ratio of this generator's output must be at least 10 dB better than that of the SMK.

Test setup:

Synchronize the reference frequencies of the SMK and reference-signal generator. The measurements are made as with the 10-MHz setup.

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3.2.13 Broadband Noise

In order to measure the broadband noise with an RF analyzer, the SMK carrier signal is attenuated with a filter.

SMK settings: unmodulated

Test setup:

Measurements: a) On the SMK, set the carrier frequency and set the level to -22.9 dBm.

b) Set the switchable lowpass filter to the lowest value that still passes the carrier.
c) Read off the carrier level on the analyzer. This level plus 40 dB is the reference level.
d) Set the lowpass filter to the next lower filter.
e) On the SMK, set level to 17.1 dBm.
f) Read off the noise level on the analyzer and convert to the level per 1-Hz bandwidth. This level, referred to the reference level (c) is the required broadband noise level.

The broadband noise level must not exceed -140 dBc.

3.2.14 Residual FM

SMK settings: unmodulated, level 0 dBm.

Test setup:

Measurements: a) Measure the residual FM with the CCITT weighting filter and rms-responding detector. (The residual FM of the deviation meter used must be < 0.5 Hz.)

Permissible residual FM < 1 Hz.

b) Measure residual FM unweighted (30 Hz to 20 kHz) with rms-responding detector. (The residual FM of the deviation meter used must be < 1.5 Hz.) Permissible residual FM < 3 Hz.

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SMK settings:	FM INT. a) 150 Hz b) 400 Hz c) 1 kHz d) 3 kHz e) 15 kHz
Test setup:	Connect frequency counter and voltmeter to the front-panel modulation socket FM1.
Test:	The frequency error must not exceed 0.1%. The output voltage should lie between 0.95 and 1.05 V. The distortion factor at 1 kHz should be < 0.05%.
3.2.16 Modul	ation Generator Sweep Signal
SMK settings:	FM, a) 3 Hz b) 30 Hz c) 100 Hz
Test setup:	Connect frequency counter and voltmeter to the front-panel modulation socket FM1.
Test:	The permitted frequency error is ±0.1%. The output peak voltage should lie between 4.75 and 5.25 V.
3.2.17 Funct	ional Test of Modulation Inputs
SMK settings:	Level O dBm, a) FM EXT 100 kHz b) AM EXT 80%
Test setup:	Apply the modulation signal 1 kHz at 1 V ±1% to the appropriat modulation input socket. Connect modulation analyzer to the RF socket.
Test: a)	With modulation inputs to sockets FM1 and FM2, the error must not exceed 3% of the set value. With the modulation input to socket FM3 (pilot tone), the frequency deviation must lie between 6 and 7.4 kHz.
ь)	With modulation inputs to sockets AM1 and AM2, the error must not exceed 5% of the set value.

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3.2.18	Automatic	Level	Control	of	External	Modulatio	n

SMK settings: Level 0 dBm, a) FM EXT 100 kHz b) AM EXT 80%

Test setup: Apply 1-kHz signal to the modulation input FM1 or AM1. Connect modulation analyzer to RF socket.
Test: Vary the input modulation signal from 0.5 to 2 V. The measured frequency deviation or modulation depth must not vary more than 1% over this range of input variation.

3.2.19 AM Modulation Depth

SMK settings: Level 0 dBm, frequency 0.1 to 140 MHz, AM INT 0.5 to 80%, f_mod = 1 kHz.

Test setup: Connect modulation analyzer to RF socket.

Test: The deviation of the modulation depth from the set value must not exceed 5%.

3.2.20 AM Distortion Factor

SMK settings: Level 0 dBm, frequency 0.1 to 140 MHz, AM INT 80%, fmod = 1 kHz.
Test setup: Connect modulation analyzer with distortion meter to RF socket.

Test: For carrier frequencies up to 2 MHz, the AM distortion factor must not exceed 0.5%. For carrier frequencies above 2 MHz, the AM distortion factor must not exceed 1%.

3.2.21 AM Frequency Response

SMK settings: AM EXT 80%, level 0 dBm.

Test setup:

Test: The modulation depth must not vary more than 1 dB from set value for modulation frequencies from 20 Hz to 10 kHz.

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3.2.22 ALC (AM DC)

SMK settings:	Level 0 dBm, AM EXT 100%
Test setup:	Connect power meter to RF output of SMK.
Test:	A DC voltage of +1.41 V applied to the rear-panel modulation socket AM2 must raise the RF level by 5.5 to 6.5 dB. A voltage of -1.41 V must result in an attenuation of at least 26 dB.

3.2.23 Residual AM

SMK settings:		unmodulated, level 0 dBm
Test setup:		Connect modulation analyzer to RF socket.
Test:	a)	Measure the residual AM with a CCITT weighting filter and an rms-responding detector. Permissible residual AM < 0.01%.
	Ъ)	Measure residual AM unweighted (30 Hz to 20 kHz) with an rms-responding detector. Permissible residual AM < 0.02%.

3.2.24 Incidental ØM in AM Operation

SMK settings:	AM INT 30%, f _mod = 1 kHz, level 0 dBm,
	frequency 0.1 to 140 MHz.
Test setup:	Connect modulation analyzer to RF socket.
Test:	The incidental ØM must not exceed 0.1 radian.

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3.2.25 Intermodulation Suppression in 2-tone AM Operation

SMK settings: AM INT 40%, f_mod = 3 kHz, level 0 dBm, frequency 0.1 to 140 MHz.

Test setup:

Test:

Set AF generator to 1 V and 3.4 kHz. Measure the 3rd order intermodulation products on the

RF analyzer.

The intermodulation suppression must be down > 40 dB.

3.2.26 FM Frequency Deviation

SMK settings:	FM INT 0.05 to 500 kHz, f _mod = 1 kHz,
	level 0 dBm, frequency 10 MHz.
Test setup:	Connect modulation analyzer to RF socket.
Test:	The measured frequency deviation must not differ
•	from the entered deviation by more than 3%.

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3.2.27 FM Distortion

Settings on SMK: FM EXT 100 kHz.

AF generator: 1 V, 100 Hz to 20 kHz.

Test setup:

Test:

a) At a modulation frequency of 1 kHz the FM distortion factor must not exceed 0.05%.

b) In the range 100 Hz to 20 kHz the distortion factor must not exceed 0.2%.

3.2.28 FM Frequency Response

Settings on SMK: FM EXT 100 kHz.

AF generator: 1 V, 20 Hz to 100 kHz.

Test setup: Connect AF generator to modulation input FM1. Connect modulation analyzer to RF socket.

Test: The modulation frequency response over the range from 20 Hz to 100 kHz must not vary by more than 0.2 dB (difference between highest and lowest level value).

3.2.29 FM DC

SMK settings: FM EXT DC 100 kHz.

Test setup: Connect frequency counter to RF output of SMK.

Test: A DC voltage of 1.41 V applied to rear-panel modulation socket FM2 must result in a frequency shift of 95 to 105 kHz.

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3.2.30 Stereo Separation

SMK settings: FM EXT 46.5 kHz, level 0 dBm, frequency 10.7 MHz.

Test setup:

Test:

a) Connect the stereocoder to the rear-panel modulation socket FM2.

Adjust the output signal of the stereocoder so that 46.5 kHz are generated. The pilot tone alone should generate about 6.8 kHz. The L- or R-signal should generate 40 kHz nominal deviation.

Read off the stereo separation on the stereodecoder.

b) Connect the stereocoder to the front-panel modulation socket FM1 and measure the crosstalk.

The stereo separation should be greater than

45 dB in the range 40 Hz to 15 kHz, 56 dB in the range 500 Hz to 10 kHz.

3.2.31 Unweighted S/N Ratio Stereo

SMK settings: FM EXT 46.5 kHz, level 0 dBm, frequency 10.7 MHz.

Test setup:

3.17

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3 e K. e K.

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3.2.32 Unweighted S/N Ratio Mono

SMK settings: FM INT 40 kHz, f_mod = 1 kHz, preemphasis in, level 0 dBm, frequency 10.7 MHz.

Test setup:

Test:

Switch in the deemphasis on the modulation analyzer. Switch out the modulation and measure the unweighted S/N ratio (CCIR 30 Hz to 20 kHz).

The unweighted S/N ratio for mono must be at least 76 dB.

3.2.33 Preemphasis

SMK settings: FM EXT 40 kHz, preemphasis in.

Test setup:

Test:

Switch in the deemphasis on the modulation analyzer. The modulation frequency response from 40 Hz to 15 kHz must not vary by more than 0.5 dB (difference between highest and lowest level value).

3.2.34 Incidental AM in FM Operation

SMK	settings:	FM	INT	40 kHz,	fmod =	= 1	kHz.

Test setup: Connect modulation analyzer to the RF socket.

Test: The incidental AM must not exceed 0.2%.

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3.2.35 SSB Test Input Intermodulation Suppression

SMK settings: Frequency 0.1 to 140 MHz, level -1 dBm, RCL.11.

Test setup:

Measurements: a) Set RF generator 1 to 40.0011 (40.04) MHz.

b) Set RF generator 2 to 40.0017 (40.07) MHz.
c) Set the level of RF generators 1 and 2 so that the input level to the SSB test input is -20 dBm.
d) Measure the 3rd order intermodulation products on the RF analyzer.

The intermodulation suppression must be at least 60 dB.

3.2.36 Interface Functions

Connect the SMK to a control computer. Send the commands listed in Table 2-2 and check their execution on the displays.

3.2.37	Response	Threshold of Overvoltage Protection,
	Option SI	МК-ВЗ
SMK setti	ngs:	Unmodulated, level -27 dBm, frequency 20 MHz.	an ta st Stationaria
Test setu	p 1:	Apply a DC voltage to the SMK RF output.	ne 1857
Test:		The overvoltage protection must respond to a voltage between 4 and 7 volts.
Test setu	p 2:	With a power signal generator with an output capability of 0 to 2 W, feed a 25- to 500-MHz signal into the RF output.	7 7 8 9 ¥
Test:		The overvoltage protection must respond to a RF power input of between 0.5 and 1 watt.

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26.2.2

ASSA AND

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3.3 Performance Test Record

R&S Signal Generator SMK Id. No. 348.0010.02

Date .....

Name .....

File No. .....

Item No.4	Characteristics	Tested see:	Min.	Measured	Max.	Unit
1	Function Display/Keyboard	3.2.1	-		-
2	Frequency setting	3.2.2	-		-
3	Output level (19 dBm) Frequency response Level at 20 MHz	3.2.5	_ 18.5		1 19.5	dB dBm
4	Noninterrupting variation Error at -10 dB (20 MHz)	3.2.7	-0.5		+0.5	dB
5	Output reflection coeff. VSWR at 3 dBm (140 MHz)		-	••••	1.2
6	RF2 output Level at 20 dBm	3.2.9	-16	•••••	-10	dBm
7	Harmonics at 1 dBm	3.2.10	-		-30	dBc
8	Nonharmonics at 39 MHz 80 MHz 90 MHz 100 MHz 119.995 MHz 140 MHz	3.2.11			-65 -65 -65 -65 -65 -65	dBc dBc dBc dBc dBc dBc dBc
9	SSB phase noise at 10 MHz 5 kHz from carrier 20 kHz from carrier	3.2.12			-125 -130	dBc dBc
- 10	Broadband noise	3.2.13	_		-140	dBc

Page 90

Item No.	Characteristics	Tested see:	Min.	Measured	Max Unit
11	Residual FM (rms) CCITT 30 Hz to 20 kHz	3.2.14		•••••	1 3 4 1 3
12	Modulation generator sinewave Frequency error Output voltage	3.2.15	- 0.95		0.1 % ^19.1 1.05 V %
13	Modulation generator sweep Output voltage	3.2.16	4.75		5.25 Vp
14	AM modulation depth, f _mod = 1 kHz at 2 MHz m = 30%	3.2.19	28.5		51.5 57.7 57.7
	m = 80% 10 MHz m = 30% m = 80%		28.5 76		84- 31-5 % 84 %
	50 MHz m = 30% m = 80%		28.5 76 28.5		¹ 371.5 % 84 % 31:5 %
	m = 80%		76		84 %
15	AM distortion m = 80%, fmod = 1 kHz, at 2 MHz 10 MHz	3.2.20			0:5 %
	50 MHz 140 MHz		-	•••••
16	ALC (AM DC) +1.41 V -1.41 V	3.2.22	5.5	•••••	6.5 dB -26 dB
17	FM frequency deviation f _mod = 1 kHz	3.2.26
	deviation = 10 kHz 100 kHz 500 kHz		9.7 97 485		10.3 kHz 103 kHz 545 kHz
18	FM distortion, deviation = 100 kHz	3.2.27	м	: بل سب السب الم
	fmod = 100 Hz 1 kHz			•••••	0.2 %

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Item No.	Characteristics	Tested see:	Min.	Measured	Max.	Unit
19	FM DC, deviation = 100 kHz Δf at 1.41 V	3.2.29	95	•••••	105	kHz
20	Stereo separation 40 Hz to 15 kHz 500 Hz to 10 kHz	3.2.30	45 56	•••••		dB dB
21	Preemphasis, error	3.2.33	-	•••••	0.5	dB
22	SSB test input Intermodulation suppression at 2 MHz 10 MHz 30 MHz 140 MHz	3.2.35	60 60 60 60	•••••	- - -	dB dB dB dB
23	Interface functions	3.2.36	-

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348.0010.02

意

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