Main Menu · Home · Calibration Forum · Calibration Directory · Calibration Jobs · Calibration Software · Calibration Books · Auction · Contact Us · Link To Us Who's Online There are currently, 5 users online. Calibration Books · Basic Metrology for ISO 9000 Certification · Analytical Method Validation & Instrument Calibration · Optical Metrology for Fluids Combustion and Solids · The Handbook Of Surface Metrology · Speckle Metrology · Measurement and Instrumentation Principles · ISO 9000 Family of International Standards [E-BOOK: ADOBE READER] · Measure for Measure: The Story of Imperial, Metric, and Other Units · BS/EN/ISO 17025:2000 General Requirements for the Competence of Testing and Calibration Laboratories · Measurement Uncertainty: Methods and Applications, Third Edition Oscilloscope Bandwidth A member of our forum asks: Hi people, Can anyone help me with a different method for establishing oscilloscope bandwidth. My problem lies in calibrating 1M ohm impedance scopes up to 250M ohm. We currently use a levelled sinewave source (SG503), set up 6 divisions on the scope at 50kHz, increase the frequency until display drops by 3dB and hey presto a bandwidth measurement. All this would be great if the impedance of the scope stayed anywhere near 1M ohm. However at frequencies of 150-250 MHz the 1M ohm actually drops below 50 ohm on most scopes (depending on input capacitance) 50 and 50 in parallel means the SG503 is driving into anywhere down to 25 ohms. I have found that almost 1dB can be lost due to mismatch, and the uncertainty of measurement is BAD! I know a fast rise can be used but that throws up a whole new set of problems regarding the mismatch and the filter properties of the scope input. Can anyone help. How do calibration labs achieve good uncertainties? Find this post here. Thermal Imaging Camera Infrared Thermometer © Copyright 2005 Title Tags Ltd Registered in England and Wales No. 05955435 All rights reserved.