The model WK-20-8350 is an integral part of the precision measuring system used by the FAA for calibration of Navigation Aids such as the Instrument Landing Systems (ILS), MLS, VOR, TACAN, and VORTAC. In ILS calibration, an operator tracks the “Flight Check” aircraft and adjusts the theodolite so that the image remains in the crosshairs. The theodolite azimuth and elevation readings are continually transmitted to the aircraft receiver by the UHF telemetric unit. The received theodolite signal is processed along with the received glide slope signal in the aircraft, to determine any errors in the signal of the ILS on course. This process is repeated for the localizer. The information is used to adjust the angle of the ILS glide scope and localizer signal transmission. This ground-based theodolite method is the most precise and accurate calibration method available. All of the Warren-Knight 20-8300 Series Theodolites, including this one, come furnished complete in a substantial carrying case and with the following accessories: a waterproof canvas cover, a sunshade, adjusting pins, a spanner wrench, an accessory tool, a screwdriver, spare bulbs and a Handbook Instruction Manual. The WK-20-8300 Series Theodolites have a telescope with a bent axis type and a 21 power main telescope. They have a 4 power wide angle finder telescope viewed through the one eyepiece. The shipping weight is 55 lbs.
- Length: 13.1”, counterbalanced, moisture and dustproof-internal focusing by rack and pinion – minimum focus 100’ with 21x power – all lenses with low reflection coating.
- Main Telescope: 42mm diameter achromatic doublet objective – effective aperture 40mm- resolving 4 seconds – 2 degree field of view.
- Finder Telescope: 17mm diameter achromatic doublet objective – effective aperture 15mm – fi eld of view 100 degrees
- Eyepiece: Four element achromatic – .074” diameter exit pupil – 15/32” eye relief – molded soft rubber eye guard
- Sights: Two pair, one fi xed, one folding (hinged), mounted on telescope for quick alignment and spotting.