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The Tektronix 492 is a spectrum analyzer with a frequency range of 10 kHz to 21 GHz in coax, and up to 325 GHz with external waveguide mixers (492PGM N/A). The P suffix designation indicates GPIB Programmability.

During the lifespan of the instrument, the specifications and included options were altered several times. A major upgrade was the introduction of the 492A in 1987 which added marker functionality and resolution bandwidths and the 492BP in 1989 which added a counter and increased the displayed dynamic range. The 492PGM is a cost reduced version introduced in 1990. Also see 49X Series Comparison.

Key Specifications

  • Coaxial Input Bands: 10 kHz to 21 GHz
  • External Waveguide mixers: 10 kHz to 325 GHz (applies to 492BP not 492PGM)
Frequency Span 492BP: 100 Hz/div to 10 GHz/div; 492PGM: 200 MHz to 1 GHz; both in 1, 2, 5 sequence; plus 0 Hz and MAX
Resolution Bandwidth (-6 dB bandwidth) 492BP: 100 Hz to 3 MHz; 492PGM: 1 kHz to 3 MHz; both in decade steps
RF Input 50 Ω, max. +30 dBm (1 W) CW; / 75 W peak pulse (1 µs, 0.1% duty factor)
RF Attenuator 0 dB to 60 dB, 10 dB steps
Reference Level -117 dBm to +30 dBm
Sweep Speed 10 sec/div to 20 µs/div, 1−2−5
Video Bandwidth 492BP: 0.3 Hz to 30 kHz; 492PGM: 3 Hz to 30 kHz
Memory NVRAM for up to 9 waveform displays, up to 10 front panel setups, plus 8 K for programming macros
Triggering Modes Free Run, Line, Video, Single, External
Displayed Average Noise −30 dBm to −131 dBm
Display Dynamic Range 492BP: 90 dB; 492PGM: 80 dB
Calibrator (Cal out) 50 Ω, -20 dBm ±0.3 dB at 100 MHz
Weight 492BP: 21.8 kg (47 lbs) 492PGM: 21.3 kg (46 lbs)
Power 90 − 132 VAC, 48 to 440 Hz; 180 – 250 VAC, 48 to 440 Hz. At 115 VAC, 60 Hz, 210 W max


  • Opt. 01: Internal Preselection. (Limits the first band to 1.8 GHz instead 4.2 GHz). Later became standard
  • Opt. 02: Digital Storage. Later became standard
  • Opt. 03: Frequency Stabilization & 100 Hz Resolution. Later became standard
  • Opt. 07: 75 Ω dBmV input and calibration in addition to the normal 50 Ω dBm input and calibration. (Not combinable with Opt. 21 and 22; no external mixer capability). Include 42-inch 75 Ω BNC-BNC coax cable and BNC male to “F” female adapter.
  • Opt. 21: (492BP) High performance 18 to 40 GHz WM490 Series Waveguide Mixer Set
  • Opt. 22: (492BP) Same as Opt. 21 plus WM490U (40-60 GHz) Waveguide Mixer
  • Opt. 23: GRASP software, PC2A interface, and GPIB cable
  • Opt. 27: Epson LT-386SX, GRASP software, PC2A interface, and GPIB cable
  • Opt. 28: Compaq Deskpro 386S, Model 40, GRASP software, PC2A interface, and GPIB cable
  • Opt. 39: Non-lithium (Silver) batteries for battery-backed memory
  • Opt. 41: Digital Microwave Radio Measurement Enhancement package
  • Opt. 42: Replaces MARKER/VIDEO input port on the rear panel with a 110 MHz IF output port that provides a 3 dB signal bandwidth ≥ 4.5 MHz
  • Opt. 45: (all except 492PGM) MATE/CIIL language interface


Documents Referencing 492

Document Class Title Authors Year Links
Tekscope 1980 V12 N1.pdf Article Packaging A Spectrum Analyzer for Performance, Maintainability and Survival Carlos Beeck 1980
Tekscope 1980 V12 N1.pdf Article A First Converter With Field Replaceable Diodes Phil Snow 1980
Tekscope 1980 V12 N1.pdf Article A Switching Power Supply For The 492 Spectrum Analyzer David Leatherwoood 1980
Tekscope 1980 V12 N1.pdf Article A Portable High-Performance Microwave Spectrum Analyzer Dave Morton 1980
Tekscope 1980 V12 N1.pdf Article The Tektronix 492 Is A New-Generation Spectrum Analyzer Morris Engelson 1980
Tekscope 1980 V12 N1.pdf Article Making Measurements with the 492 Morris Engelson 1980


Front panel inputs/outputs are:

  • RF INPUT (50 Ω N connector) – Input for RF signals to 21 GHz. If input signal has a DC component, use a blocking capacitor
  • CAL OUT (BNC connector) – Provides 100 MHz, –20 dBm signal and a comb of frequency markers 100 MHz apart
  • 1ST LO OUTPUT (SMA connector) – Output of the 1st local oscillator, must be terminated into 50 Ω when not connected.
  • 2ND LO OUTPUT (SMA connector) – Output of the 2nd local oscillator, must be terminated into 50 Ω when not connected.
  • EXTERNAL MIXER RF INPUT (TNC connector, 50 Ω)
  • Camera Power

Rear panel inputs/outputs are:

  • PROBE POWER – Provides operating voltages (+5 V, -15 V, +15 V; 100 mA max each) for active probes
  • HORIZ/TRIG (input, BNC) – In External Triggering mode, AC coupled input for trigger signals; when TIME/DIV selection is EXT, DC coupled input for horizontal sweep voltages
  • MARKER/VIDEO (B053575+, output, BNC) – interfaces the 492/492P with a TV Sideband Adapter, such as the Tek 1405, so a marker from the adapter is displayed on the internal video. External video applied to this connector will also be displayed if pin 1 of the ACCESSORIES connector is grounded.
    • Opt. 42 replaces MARKER/VIDEO with 110 MHz IF (output, BNC) – 3 dB signal bandwidth ≥ 4.5 MHz
  • EXT PRESELECTOR (B053574 and below) (output, BNC) – variable voltage (approx -0.2 V to +10 V) proportional to center frequency, for preselector bands of Opt. 01 instruments, to drive an external preselector
  • HORIZ (output, BNC) – 0.5 V/div horizontal signal
  • VERT (output, BNC) – Video signal with 0.5 V/Div
  • PEN LIFT (output, BNC) – TTL compatible signal to lift the pen of a chart recorder during sweep retrace. In Opt. 42 instruments this port may also be used for inputting external video if pin 1 of the ACCESSORY connector is grounded.
  • 10 MHz IF (output, BNC) – Output of the 10 MHz IF
  • J104 ACCESSORY (B053575+ only), female DB25 connector – Provides bidirectional access to the instrument bus.
  • IEEE STD 488 PORT GPIB interface – Added to all "P" suffixed instruments