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Used Tektronix 492 Spectrum Analyzer - $1,800 (Frederick)
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Includes a rare diplexer set to extend coverage to 26 GHz. The Diplexer includes the microwave Horn antennas all inside the unit front cover. Includes the rare user guide.
This unit is excellent for RF design, Measurements, RF Spectrum Surveillance, wide spectrum search, Astro Radio Astronomy, EMI and other niche RF analysis such as Tempest and TSCM, mmWave or Radar related efforts.
Core Capabilities:
• Frequency range: 50 kHz - 18 GHz via internal coaxial mixer; extendable to 60–220 GHz (or up to 325 GHz on some later models) with external waveguide mixers.
• Dynamic range: Typically 80 dB on-screen (up to 90 dB on later 492BP).
• Sensitivity: Displayed average noise level down to approximately –115 to –131 dBm (depending on band, resolution bandwidth, and options).
• Resolution bandwidth: 1 kHz to 1 MHz.
• Reference level: Roughly –117 / –123 dBm to +30 / +40 dBm.
• RF input: 50 Ω; max safe input +30 dBm (1 W) CW.
• Attenuator: 0–60 dB in 10 dB steps.
Tektronix 492 external diplexer (for ~26 GHz operation) with waveguide mixers and horn antennas
The Tektronix 492 (and related 49X-series analyzers) uses an external diplexer (part number 015-0385-00) as a standard accessory when operating with external waveguide mixers above ~21 GHz. This enables coverage into the K-band (including 26 GHz) and higher millimeter-wave bands.
Diplexer Role and Connections
• The diplexer is a directional filter / hybrid that combines three signals onto a single cable to the external mixer:
• 1st LO drive (from the front-panel SMA 1st LO OUTPUT, typically +7 to +15 dBm, swept ~2–6 GHz).
• IF return (primarily 2.072 GHz for external-mixer bands; also supports 829 MHz in some modes).
• DC bias for the mixer diode (adjustable via the PEAKING control, roughly –2 V to +1 V / 0–20 mA).
• Connections:
• Semi-rigid SMA cable + TNC-to-SMA adapter link the analyzer’s 1st LO OUTPUT and EXT MIXER (TNC) port to the diplexer.
• A flexible SMA cable runs from the diplexer to the waveguide mixer.
26 GHz (K-band) Waveguide Mixer
For the ~18–26.5 GHz range (Band 6 on the 492):
• High-performance mixer: WM490K (earlier part 016-0631-01).
• Waveguide: WR-42.
• Flange: UG-595/U (standard rectangular).
• Typical sensitivity: ≈ –100 dBm (1 kHz RBW).
• Frequency response: ±3 dB (about mean average).
• Amplitude accuracy: ±6 dB (referenced to 100 MHz).
• 3 dB compression: ≈ –10 dBm typical.
• Max RF input: ~+10 dBm CW / 10 mW peak (use attenuator or coupler to stay linear).
• Field-replaceable diode.
$1800
Sold As Is
Good Working Condition
Local Pickup Frederick Md area
No Returns
Calibration unknown
Includes: Front Cover, Diplexer/K Band Horns, power cord.