HP X810B Slotted Line Section WR90 Waveguide X-Band 8.2-12.4 GHz Hewlett-Packard

HP X810B Slotted Line Section WR90 Waveguide X-Band 8.2-12.4 GHz Hewlett-Packard

The Hewlett-Packard X810B is a precision slotted line (slotted section) designed for WR90 rectangular waveguide, covering the X-band frequency range of 8.2 to 12.4 GHz. A slotted line is a fundamental RF and microwave measurement instrument used to measure standing wave ratio (SWR), reflection coefficient, and impedance by detecting the field distribution along a longitudinal slot cut into the broad wall of the waveguide. The X810B features a motor-driven or manual carriage that traverses a detector probe along the slot, with position read from a calibrated graduated scale. Note: the detector probe assembly — the fine wire probe that fits into the 0.50" diameter detector plug and extends slightly into the slot to couple with the crystal detector — is missing on this unit. The mechanical carriage, traversing rails, thumbwheel drive, and scale are intact and functional.

Specifications & What's Included

• Manufacturer: Hewlett-Packard (HP)
• Model: X810B (Slotted Section)
• Waveguide size: WR90 (EIA standard, 0.900" × 0.400" inside dimensions)
• Frequency range: 8.2 – 12.4 GHz (X-band)
• Slot type: Longitudinal slot in broad wall of WR90 waveguide section
• Carriage: Precision traversing carriage with thumbwheel drive mechanism
• Scale: Calibrated brass graduated scale along the full length of the slot
• Detector mount: Circular 0.50" diameter detector plug mount — probe wire and detector plug assembly are missing
• Compatible detector: Crystal detector type; probe can be fabricated using a 1N23 crystal diode
• Flanges: Standard WR90 waveguide flanges on both ends for in-line mounting
• Leveling: Adjustable leveling feet/screws on the frame
• Condition note: Some dust present inside the waveguide section; nameplate shows surface paint loss and minor corrosion
• Included: Slotted line body and carriage only — no detector probe, no crystal detector plug, no cables or accessories

Applications

Slotted lines are a classic microwave measurement technique dating from the 1940s–1960s, and the HP X810B represents the precision instrument-grade refinement of that technology from the Hewlett-Packard era. They are used in RF and microwave laboratories to measure the standing wave pattern along a transmission line or waveguide, from which standing wave ratio (SWR), reflection coefficient, and load impedance can be calculated. For WR90 waveguide at X-band, typical applications include antenna impedance matching, waveguide component characterization, filter and attenuator testing, and educational demonstration of transmission line theory. Slotted lines were standard equipment in defense electronics labs, university microwave research facilities, and radar and satellite system development during the 1950s through 1980s. While largely superseded by vector network analyzers (VNAs) for routine measurement, slotted lines remain valued in legacy lab setups, educational institutions, and by collectors of classic HP/Agilent microwave instrumentation. The X810B in working mechanical condition with a fabricated or sourced replacement probe can still serve as a fully functional measurement instrument for X-band waveguide work.